JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2019, 70, 3, 337-355 www.jpp.krakow.pl | DOI: 10.26402/jpp.2019.3.02

Review article

K. JURKOWSKA 1, E.M. KRATZ 2, E. SAWICKA 1, A. PIWOWAR 1

THE IMPACT OF METALLOESTROGENS ON THE PHYSIOLOGY OF MALE REPRODUCTIVE HEALTH AS A CURRENT PROBLEM OF THE XXI CENTURY

1Department of Toxicology, Faculty of Pharmacy with Division of Laboratory Diagnostics, Wroclaw Medical University, Wroclaw, Poland; 2Department of Laboratory Diagnostics, Faculty of Pharmacy with Division of Laboratory Diagnostics, Wroclaw Medical University, Wroclaw, Poland

In the XXI st century in highly developed countries, progressively decreasing male reproductive potential is indicated. In recent years epidemiological studies indicate the deterioration of semen parameters: reduction of ejaculate volume, sperm count, and mobility, as well as abnormalities in their morphology. Male infertility can result from many different agents, such as: anatomical or genetic abnormalities, systemic or neurological diseases, infections, trauma, iatrogenic injury, gonadotoxins and development of sperm antibodies and lifestyle (especially obesity, heat and tobacco smoking). It is well documented that adverse changes in male fertility also seem to be associated with environmental exposure to different substances, especially endocrine active factors, known as xenoestrogens, and among these metal ions, known as metalloestrogens, are very important. The role of some metalloestrogens in various diseases, both in women and men, is known and particularly well-proven in women, but still little is known about their role in the regulation of male reproductive potential. Thus we decided to analyse the available information exploring this problem. The review was carried out using the Medline and Google Scholar databases, using the keywords: xenoestrogens, metalloestrogens, male fertility, semen quality, male reproductive potential, mechanisms of metalloestrogen action, environmental pollution and the name of the particular metal. Articles published between 2000 – 2019 have been taken into account, including human and vertebrate animal studies and cell lines. The aim of this review is to discuss the role and mechanisms of action of fifteen metalloestrogens in the human organism, as well as in animal models, and cell cultures, paying special attention to their influence on the physiology of male reproductive health, according to the current state of knowledge. The role of certain metals in human reproduction is still poorly investigated and for some of them only single studies are available. Many factors in our daily lives have a significant impact on male fertility, therefore education is necessary on the threats and how they may be eliminated as far as possible.

Key words: xenoestrogens, metalloestrogens, male fertility, semen parameters, mechanisms of metalloestrogen action

INTRODUCTION idiopathic infertility. The first long-term meta-analysis was conducted by Carlsen et al . (9), who analysed this problem in Over the last decades, in highly developed countries, a detail and published the results of their study in 1992. This study visible trend of birth rate reduction is observed. One of the documented significantly decreased semen parameters such as causes of this negative phenomenom is the observed progression sperm count and seminal volume of about 41% and 19%, in the reduction of male reproductive potential. Male infertility respectively, over 50 years of observation (from 1940-990). can result from many different agents, such as: anatomical or Since then, many studies have been published comparing the genetic abnormalities, systemic or neurological diseases, quality of semen in various countries. For example, a infections, trauma, iatrogenic injury, gonadotoxins and the retrospective and descriptive study conducted in France showed development of sperm antibodies, lifestyle (especially obesity, a decrease in sperm concentration of about 32% over the period heat and tobacco smoking) and environmental factors (1-3). 1989 – 2005. Additionally, a significant, but not quantifiable, Current epidemiological studies especially indicate a decrease in the percentage of sperm with morphologically deterioration of semen parameters in recent years: a reduction in normal forms was observed (10). There was also a reduction in volume, sperm count and mobility, and changes in morphology semen volume (43%) in men aged 35 – 50, which constitutes an (4, 5). The World Health Organization (WHO) has reported approximate 32% decline in sperm counts and an overall 57% (1980, 1987, 1992, 1999 and 2010) on deteriorating values of diminution in mean sperm concentration in different semen parameters in the population, and male infertility has geographical regions of the world (11, 12). The increased become a civilizational disease of the XXIst century (6-8) ( Table number of cases of cryptorchidism and hypospadias is also a 1). Moreover, there is a large percentage of normozoospermic serious problem (13). Additionally disturbances in plasma men (physiological values of standard semen analysis) with prooxidant/antioxidant balance parameters ( e.g. melatonin, 338

Ta ble 1 . Values of selected parameters of standard semen analysis presented in WHO reports from the years 1992, 1999 and 2010. Semen parameters WHO report 1992 WHO report 1999 WHO report 2010 Type of abnormalities when parameter decreased Semen volume ≥ 2 mL ≥ 2 mL ≥ 1.5 mL aspermia (lack of ejaculation) pH ≥ 7.2 – 8.0 ≥ 7.2 ≥ 7.2 Time of liquefaction < 60 min < 60 min < 60 min Sperm count: 1. for 1mL 1. ≥ 20 ml ./mL 1. ≥ 20 mln /mL 1. ≥ 15 mln /mL oligozoospermia , 2. total (in ejaculate) 2. ≥ 40 mln /ejaculate 2. ≥ 40 mln/ ejaculate 2. ≥ 39 mln/ ejaculate azoospermia (no sperm in ejaculate) Sperm mobility 1. fast progressive 1. ≥ 50% 1. ≥ 50% 1.  40% asthenozoospermia movement + slow progressive movement (a + b) 2. fast progressive 2. ≥ 25% 2. ≥ 25% 2. ≥ 32% movement Sperm vitality ≥ 75% ≥ 50% ≥ 58% Sperm morphology ≥ 30% ≥ 14% ≥ 4% theratozoospermia Leukocytes < 1 mln /mL < 1 mln /mL < 1 mln /mL (peroxidase -positive)

The data was prepared on the basis of information analyzed by Olejnik and Kratz (6-8). In gray were marked the main changes in seme n par ame ters in W HO 201 0 rep ort when comp ared with pr evious W HO repo rts, as w Iel l as t he na mes of m ain type s of sem en abnormalitie s.

advanced oxidation protein products (AOPP), total antioxidant these metals, especially those referred to as ‘heavy metals’, are capacity (TAC) as well as proteases/inhibitors balance toxic for wildlife, experimental animals, and humans. Many parameters ( e.g. metalloproteinases MMP-2 and MMP-9, and experimental studies, especially those derived from recent years, their inhibitors - TIMP-1 and TIMP-2) are indicated as important on animals and humans occupationally or environmentally element affecting the semen condition and their mutual exposed to some of these heavy metals, show their negative relationships will be interesting aspect of future studies (14). impact on the physiology of reproductive health (26-31). It should be underlined that adverse changes in male fertility Information on the effects of other metals and transition metals may also be associated with environmental exposure to different on male reproductive outcomes is limited, however it is substances, especially endocrine active xenobiotics, which are documented that most of the ions of these metals may influence capable of disturbing endocrine homeostasis in the organism. estrogen receptor (ERs) function, and are capable of binding to They are known as xenoestrogens (XEs), and also known as cellular estrogen receptors and then mimicking the action of endocrine disruptors (EDCs) (15). The endocrine active physiological estrogens (22-33). They can significantly substances significantly affecting the male reproductive system, modulate the hormonal status of the organism and finally induce also known as endocrine disruptors, could be xenoestrogens or many disturbances in human organism homeostasis (33-35). A xenoandrogens (16, 17). Over the last few years, more and more scheme illustrating the influence of metals in air pollution, evidence indicates the influence of XEs derived from different drinking water and food on male fertility is shown on Fig . 1. The sources ( e.g. diet, environmental pollution, tobacco smoke, role of some MEs in cancerogenesis, both in women ( e.g. breast cosmetics), which seems to be crucial in the development of or endometrium cancer) and men ( e.g. testicular or prostate male infertility (18-20). They can definitely reduce the cancer) is known and particularly well proven in women (36- reproductive potential of men, acting mainly by disrupting the 39), but still little is known about their role in the regulation of endocrine hormonal system at certain doses, as well as male reproductive potential, therefore we decided to analyse the participating in carcinogenesis of endocrine target tissues (21). available information exploring this problem. The unfavorable influence of endocrine disruptors on the The aim of this review is completion of the available physiology of male fertility is indicated by epidemiological information about the role and mechanisms of metalloestrogen studies, which suggest that male fertility disorders occur mainly action in the human organism and their influence on the in developed countries (22, 23). Exogenous estrogens are highly physiology of male reproductive health, according to the current heterogeneous in structure and include synthetic organic state of knowledge. In our review we have also included the compounds such as pesticides and plastics, as well as natural results of investigations based on animal models and cellular plant-derived xenoestrogens, i.e. phytoestrogens. The role and research to better characterize the topic discussed, since the mechanisms of action of many XEs belonging to different investigations provided e.g. on animal models reflect changes groups of chemicals are rather well known and well described, which can also be observed in humans. On the other hand the but relatively little information applies to metal ions acting as availability of information about xenoestrogen action is higher EDCs. Such groups of metal ions with “estrogenic activity” are for e.g. animal models, than humans. The role of certain metals called metalloestrogens (MEs) (24, 25). The group of analysed in the context of their influence on male fertility is still metalloestrogens includes: aluminum (Al), antimony (Sb), poorly investigated, and for some of them only single studies are arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), cobalt available. We decided to describe first the most important and (Co), copper (Cu), lead (Pb), mercury (Hg), molibdenium (Mo), well-investigated alphabetically, and then all of the lesser known nickel (Ni), selenium (Se) tin (Sn), and vanadium (V). Most of together. 339

Our review is based on literature research, using the PubMed health of men (40). The results of some studies have shown and GoogleScholar databases, including recent data which were suppressed spermatogenesis and the development of Sertoli and published from 2000 onward in this review, mostly in English, Leydig cells in animals exposed to xenoestrogens (22). Exposure using the search terms, or their combination: xenoestrogens, to environmental estrogens during fetal life seems to be the most metalloestrogens, aluminum, antimony, arsenic, barium, significant, because the proliferation of Sertoli cells are growing cadmium, chromium, molibdenium, mercury, lead, cobalt, at this time (16, 41, 42). Xenoestrogens inhibit the secretion of a copper, nickel, selenium, tin, vanadium, male fertility, semen follicle-stimulating hormone (FSH) that affects the proliferation, quality, male reproductive potential, mechanisms of maturation and function of the supporting Sertoli cells that metalloestrogen action, environmental pollution. The study produce regulatory signals and nutrients for the maintenance of included research on human and some animal and cell models. developing germ cells. A smaller number of these cells results in Finally, 194 items from original papers and reviews were reduced mice semen production during the reproductive period selected, which in our opinion seemed to be the most useful and (43, 44). These irreversible changes also occur in humans, as is fitting regarding this issue. confirmed by studies of men with hypogonadism (45). Despite the administration of gonadotropins, the expected effects were not obtained, which indicates a lack of adequate Sertoli cells, THE ROLE OF ESTROGENS which were formed only in the perinatal period (42, 44). IN THE MALE REPRODUCTIVE TRACT Information about estrogens and their metabolites, and mechanisms of action on the estrogen receptors and cell Although estrogens are primarily the main female sex metabolism have been given in detail in the literature (25, 46). hormones, they also play an important role in the male Briefly, 17 b-estradiol (E2) is mainly formed in peripheral tissues reproductive system. For example, their participation has from testosterone (T) in an enzymatic reaction with the currently been documented in the normal course of participation of aromatase. It is produced in the adipose tissue, spermatogenesis, as well as in other aspects of male fertility. brain and adrenal glands, as well by the Sertoli, Leydig and Increasingly, it is pointed out that in men exposed to spermatogenic cells (25, 47). Production of E2 in the testicles xenoestrogens, disruption of the natural estrogen-androgen was confirmed after the administration of human chorionic balance is observed, which adversely affects the reproductive gonadotropin (HCG), when after 24 h the estrogen ejection was

Ni Hg Mo Accumulate in testes , TST, goes through the blood -testis barrier , astheno -, oligo -, theratozoospermia , tail defects Sb accumulates in Sertoli and Leyidig OS → ROS

Poor semen quality , cells asthenozoospermia ; similar action like for Pb azoospermia, OAT Co Necrosis of seminiferous tubules and the interstitial tissues , Ba Leydig cells hypetrophy , spermatogonial cells degeneration Sperm viability , abnormal sperm parameters Al Accumulation in sperm Cr asthenozoospermia ; Testicular atrophy , ROS → reproductive toxicity ; oligo -, astheno -, theratozoospermia , Metals and stimulants which influence sperm maturation and toxicity ; OS → ROS; toxic testicular damage , influence male fertility oligozoospermia, damage of Sertoli and germ cells serum TST, (air pollution , contaminated water and food) theratozoospermia Pb Cu Absorbed mainly while smoking; Cu →astheno zoospermia , libido, is included in the paper , OS, therato - oligo - and herbs , cosmetics; asthenozoospermia ; acrosomal reaction disorder , Cu →azoospermia fast accumulation in male reproductive organs , spermatogenesis , astheno -, oligo -, theratozoospermia , As OS → ROS; agglutination , Sperm quality , impaired TST synthesis in testes , sperm degradation Cd Absorbed mainly while smoking, testicular mass, OS → ROS; is included in the paper , therato -, oligozoospermia; herbs , cosmetics; Cu →azoospermia Se astheno -, oligo - and theratozoospermia , Accumulate in testes , acrosomal reaction disorder , Se → quality of ejaculate , fast accumulation in male V

antioxidants activity ; reproductive organs , Astheno -, oligo -, theratozoospermia , very high concentration→adverserly Sn TST synthesis , OS OS → ROS; serum TST, affect male fertility necrosis of Sertoli cells , disturbances oligozoospermia, in oxidative -antioxidative balance semen quality

Fig . 1. Sc h eme of infl uenc e of metals c onta ined in a ir pollution, dr ink ing w ater and food for male fe rtility. A stheno zoospe rmia - decreased sperm motility, oligozoospermia - decreased sperm count, theratozoospermia - abnormal morphology of sperm, azoospermia - no spe rm in ejacula te. Abbreviations : Al, alumin iu m; Sb, antimon y; As, ars enic; Ba, bari um; Cd, cadmium; Cr, ch ro mium; Co, cob alt; Cu, copper; Pb, lead; Mo, molybdenum; Hg, mercury; Ni, nickel; OS, oxidative stress; ROS, reactive oxigen species; Se, selenium; Sn, tin; V , vanadium ; TST, testosterone.

340 observed to be faster than the testosterone. HCG acts like the number of signaling and regulatory pathways have been luteinizing hormone (LH) - it induces T synthesis in the Leydig demonstrated as influencing 3 b-HSD transcription and activity cells (48). The presence of estrogen receptors in men has been (57-59). demonstrated in many tissues, which indicates their significant The next important mechanism among EDC actions is the role in the regulation of various physiological processes: the modulation of the bioavailability of sex hormones ( e.g. by formation of bones, inhibition of growth, lipid metabolism etc . limiting the concentration of sex hormone binding globulin E2 also regulates the function of the testicles by affecting the (SHBG)). Stimulation or inhibition of endogenous hormone proliferation of Leydig and Sertoli cells (47, 49). In vitro studies binding protein leading to decreased or enhanced circulating have demonstrated the protective effect of estrogens on hormone availability is also observed (58). SHBG, in addition to spermatozooa by preventing their apoptosis, and have been the binding of androgens and estrogens, also has an affinity for shown to increase the number of gonocytes. This view has been EDC binding, among others: phthalate esters. This leads to an confirmed by studies in estrogen receptor knockout mice - increased amount of free hormones in the circulation, and as a deprived of estrogen receptors. These mice, despite well- result, endocrine disorders (24, 54, 60). Some authors indicated developed reproductive systems at the end of the puberty on the high levels of soluble vascular endothelial growth factor process, gradually observed the disappearance of sperm receptor 1 (sFlt-1) and low levels of vascular endothelial growth production (48, 50). As a cause of infertility, the occurrence of factor (VEGF) in follicular fluid as possible predictive factor of increased pressure inside the epididymal canal as a result of the ovarian hyperstimulation syndrome (OHSS) in women (61). abnormal drainage of the fluid within the epididymal canal, is Probably it will be also interesting point of research of potential indicated. Estrogen action is required for fertility in male mice, role of VEGF and sFlt-1 in male infertility in the aspect of and mutation of the estrogen receptors (ER) in ERKO males changes of vascular permeability. (male mice with disrupted ER genes) leads to reduced mating The hypothalamic-pituitary-testicular (HPT) axis is frequency, low sperm numbers and defective sperm function. described as the last mechanism of endocrine disruption. The Estrogens were also recognized as factors initiating the process HPT is responsible for the proper functioning of the testicles and of spermatogenesis during puberty. Moreover, estrogen interacts maintains the appropriate level of T, responsible for the with FSH enhancing its stimulating effect on spermatogenesis spermatogenesis process in the testes, by the use of a negative (51). It is indicated that some metalloestrogens can influence the feedback mechanism. Pulse secretion of gonadotropin-releasing steroid synthesis of sex hormones, accumulation in the male hormone (GnRH) stimulates the secretion of FSH and LH, reproductive tract and the activation of estrogen receptors (52). which in turn stimulates testosterone synthesis in Leydig cells, thereby regulating spermatogenesis in Sertoli cells (62). High concentrations of T inhibit GnRH secretion. EDCs may interfere XENOSTROGENS AND METALLOESTROGENS with the function of the HPT by interacting with receptors for AND THEIR MECHANISMS OF ACTION LH, FSH or GnRH. Moreover, metalloestrogens may disrupt Ca 2+ flux, which is part of the cAMP cascade, interfering with As was mentioned above, xenoestrogens are exogenous the transduction of the signal after the stimulation of G protein- compounds with a diverse chemical structure commonly present coupled receptors (GPR), including LH/hCGR (63). The grip in the environment. Their common feature is an estrogen-like point for EDCs ( e.g. lead) can also be enzymes: cAMP action, but they show estrogenic effects through various dependent protein kinase A or inositol triphosphate dependent mechanisms. Xenoestrogens and their effects are widely protein kinase C, also participating in the signaling pathway discussed, particularly in relation to human reproductive health, activating GPR. It was also shown that some EDCs reduce the but lately also with reference to male infertility problems (22, expression of mRNA for hypothalamic kisspeptin (Kiss-1). Kiss- 53). Every compound from the EDC group is characterized by a 1 and its GPR54 receptor controls the secretion of GnRH and the specific mechanism of action. Due to the fact that many activation of the pituitary-hypothalamic-testes axis (64). exogenous compounds have an analogous structure to natural The chemical structure of xenoestrogens is diverse, they hormones, the direct interaction of EDCs with the estrogen have been mainly organic, in particular phenolic or carbon ring receptor located in the nucleus, by binding to the ligand binding structures of varying structural complexity (65). Lastly, more domain (LBD) present in the ER structure, is indicated as the and more scientific research concerns certain metal ions. With most common and important. It leads to stimulation (agonism) respect to metalloestrogens, which are inorganic compounds, the or inhibition (antagonism) of its transcriptional activity, indicated mechanism of action is somewhat different. This disturbing the physiological function of cells and hormonal applies either to a direct effect on the estrogen receptors or homeostasis of the organism (24, 54, 55). indirectly on the induction or intensification of oxidative stress In the second most important place among EDC actions with (OS), and hence secondary disorders caused by OS (66). ER, especially without a structure similar to the receptor, is the Additionally, influence on the regulation of gene expression and area of so-called ‘zinc fingers’ in the DNA binding domain the function of signal transduction pathways in a cell, including (DBD). These EDCs can displace zinc ions, replacing them in the pathway dependent on estrogen receptors, is also indicated DBD, having an effect on the receptor structure and influencing (16, 24) . But these mechanisms have not been fully investigated the pathways of intracellular signal transduction, interaction or described yet. with DNA and target gene expression (56). Estrogen receptors are located in the nucleus of target tissue The next possible mechanism, disorders in the synthesis of and cells and consist of fragments called domains. The two main estrogen receptors a (ER a) in Leydig cells and influence on types of ERs occur in the human organism, estrogen receptors a mRNA levels of steroidogenic acute regulatory protein (StAR) is and b (ERa and ERb, respectively). Their distribution in tissues described (57, 58). The disturbances (stimulation or inhibition) and affinities both to endo- and exogenous estrogens are in the synthesis, metabolism or degradation of endogenous different (67). In men they occur both in cells of the reproductive hormones, especially testosterone production, by affecting the system as well as in others, e.g. osteoclasts and muscle cells. activity of the synthesis and metabolism of D-5-3- b- Estrogens, acting on target tissues through estrogen receptors, hydroxysteroid dehydrogenase (3 b-HSD), 17 b-hydroxysteroid not only regulate the function of the male reproductive system, dehydrogenase (17 b-HSD), CYP11A and CYP17A and but also affect its development (56). Study conducted in animal aromatase, can be observed. It was documented that in general a model with seasonal changes in the intratesticular sex hormones 341 level revealed interesting association between the ERs which results in excessive proliferation and growth of cells (74). expression and Leydig cells function and architecture depending The receptor mechanism has been further investigated, for on these seasonal changes of endogenous estrogen status in the example for cadmium, aluminum and chromium (75). The testis, with insight into mechanism of control of animal Leydig mechanisms of action of other metals is mainly related to cells. Ultrastructure analysis revealed alterations in reactive oxygen species (ROS) generation and induction of mitochondria number as well as endoplasmic reticulum and oxidative stress or inflammatory response (33, 68). The scheme Golgi complexes volume and structure in these cells, especially of the mechanisms of xenoestrogens action on male fertility is after ER a blockage by specific inhibitor. Additionally diverse presented in Fig . 2. and complex ERs regulation at mRNA level and protein Metalloestrogens may affect fertility through direct effects expression of some steroidogenic and secretory molecules were on the reproductive organs, but also through the endocrine revealed in relations to endogenous estrogen level in treated system. They have the ability to crawl and damage the prostate, males. It was to varying degrees related to a cycle of seasonal epididymis and semen. They can also cause damage to sperm changes in the intratesticular sex hormones level (68). DNA by reducing the stability of chromatin. Damage to the Xenoestrogens, which are able to induce much deterioration Sertoli cells during fetal life causes an irreversible effect (the in the male reproductive system, act similarly (69). The most number of Sertoli cells determines the amount of sperm important part of the estrogen receptor is the structural DNA- produced - they can perform their functions for a limited number binding domain (DBD) with two zinc finger motifs of germ cells). Sertolli cells proliferate in neonatal, fetal and pre- distinguished, and this element is indicated as the main pubertal-periods (when high sensitivity to metal ions occurs) mechanism of xenoestrogens and also metalloestrogens action (16, 42). (70). These structures are formed (usually) from 30 to 40 amino acids, and spatial organization of these domains is stabilized by coordinating bonds formed between zinc ion and cystein thiol METAL IONS AS METALLOESTROGENS groups and/or imidazole histidines (71). Interaction with the ERs AND THEIR ROLE IN MALE FERTILITY by the zinc finger in the DBD receptors’ domain, disrupting receptor interaction with the DNA and target genes, is indicated. Aluminium The molecular mechanism of xenoestrogens action consists mainly of replacing the zinc ions by finger motifs in the receptor Aluminum (Al) is a natural element in the environment, DBD domain. This causes weakening or inhibition of receptor primarily in the Earth’s crust (76). It is widespread, and binding to the DNA of the target gene (72). Some of the metal distributed in various industries, including the cosmetics ions may also interact with other receptor regions, for example industry, mainly as an antiperspirant ingredient (77). Aluminium cadmium can react with ligand-binding domain (LBD), blocking compounds are used in pharmaceuticals and in water treatment the attachment of the appropriate ligand ( i.e. estradiol) to the processes (78). The relationship between aluminum exposure receptor (33, 73). Others can increase cell response to estrogens, and morbidity in breast cancer or neurodegenerative diseases has

Fig . 2. The scheme of the mechanism of xenoestrogens action and their effect on physiology of male fertility. Er a, estrogen receptor a.

342 been proven (79, 80). It has been shown that the main significant higher concentrations of aluminum were observed. mechanism of this influence is aluminum activity as an Statistical significance was not observed after analysis of other endocrine disruptor, in the main manner characteristic for metals semen parameters. However, these studies have shown that and described above (81). Additionally the induction of ROS aluminum may have a detrimental effect on spermatogenesis in production by aluminium ions as a mechanism of reproductive humans as well (87). toxicity is indicated (82). Some authors have pointed to the possibility of aluminum Arsenic influencing the processes of maturation and the production of sperm and its storage in the epididymis, which results in a Arsenic (As) is a metal widely present in the environment, reduction in sperm count. This was histologically confirmed in and one of the main sources of exposure is contaminated water Wistar rats which received orally aluminium chloride (from 475 and food (88). Toxicity to humans shows As(III) and As(V). to 1900 mg/kg b.w.) with distilled water. Aluminium showed Arsenic, like chromium, is an agent that induces oxidative stress, marked distorted seminiferous tubules with loss of normal which is indicated as the main route of its unfavorable action distribution of epithelial linning and vacuolar cytoplasm (78). In (89). Because of its huge prevalence in the environment, studies conducted on 3 generations (F1, F2, F3 - first, second, potential for human exposure, and the magnitude and severity of third filial generation, respectively) of male Wistar rats, whose the health problems it causes, the United States Agency for Toxic parents (F0 generation) were exposed to aluminium sulphate Substances and Disease Registry (ATSDR) has ranked arsenic as (from 200 to 1000 ppb, wather solutions) for six months, a No. 1 on its Priority List of Hazardous Substances for many significant reduction of serum testosterone levels was noticed in years. Arsenic is classified by the International Agency for all examined groups, compared to the control one (not exposed). Research on Cancer (IARC) as a potent human carcinogen (88, Significantly lower T concentrations in F1 and F2 than in the F0 90, 91). Chronic exposure to elevated concentrations of As has generation was connected with LH fluctuations in F0 and a also been associated with an increased risk of a number of significant LH decrease in F2 and F3 generation. Testes weight noncancerous effects (91). Although the adverse health effects decrease, increased number of immobile and abnormal sperm, arising from exposure to arsenic are well-recognized, the and histoarchitecture alterations in the testes were observed. In mechanism of action responsible for the diverse range of health all generations, a greater amount of immobile and abnormal effects is complicated and still poorly understood (93, 94). sperm in comparison to the control was also observed when It has been shown that high doses of arsenic in the form of comparing the F0 generation with F1 and F2, and a statistically inorganic salts induces apoptosis by activating enzymes significant reduction in testes weight in subsequent generations participating in hydrogen peroxide production ( e.g. was also observed, which confirms that chronic exposure to nicotinamideadenine dinucleotide phosphate (NADH)). The aluminium was significantly deleterious (27). In other animal H2O2 is secreted by macrophages associated with Leydig cells in studies, used doses of Al (exposure period 60 days) were similar the interstitium of the testes and therefore can negatively affect to those found in the human diet (8.3 mg/kg b.w./day). A sperm quality in men. It is believed that the harmful effect of significant reduction in sperm parameters such as motility, arsenic on fertility is caused by impaired T synthesis in the sperm counts and viability and a higher percentage of abnormal testes, and reduction of testes weight and accessory sex organs, sperm and impaired testes histology, even at low exposure (5 as well as morphological changes in sperm and a decrease in mg/kg b.w./day) as well as in high doses of aluminium (8.3 their amount, hence impaired spermatogenesis. Induction of mg/kg b.w./day), were observed. The authors also confirmed apoptosis is probably also associated with a reduction of increased oxidative stress in reproductive organs and mitochondrial membrane redox potential, and consequently the inflammation in the testes under aluminium exposure (83). release of cytochrome C into the cytosol, the induction of Similar results were obtained by Mouro et al . (84) in studies on caspase 3, and as a result DNA chain fragmentation (95). an animal model, further noting the dose-dependent effect. The Additionally it is believed that inorganic arsenate as a molecular authors revealed that the consequences of exposure to even low analogue of phosphate can compete for phosphate anion levels of Al were as negative as high levels on reproductive transporters and replace phosphate in some biochemical parameters, suggesting an adverse impact on male fertility in the reactions ( e.g. generation of ATP, during oxidative concentrations tolerated in drinking water, established by phosphorylation). As another important aspect of As action, its international organizations as 3.35 × 10 –4 mg/kg. They observed high affinity to thiol groups of many proteins is indicated. It is negative impacts on serum T levels, testicular histomorphometry connected with numerous disturbances of chromatin proteins and sperm parameters. Yousef et al . (85) also revealed a and spermatozoa flagella, as well as enzymes. The capability of significantly decreased number of motile and viable rabbit sperm binding trivalent arsenicals to cysteine residues in zinc fingers in after AlCl 3 treatment (10, 15 and 20 mM). The response was different receptors and direct binding of pentavalent arsenicals to both Al concentration and time dependent, as well as enhancing protein is indicated as one of the possible ways of action (96). free radical generation and alterations in the activities of many It is indicated that high arsenic level may suppress the enzymes: a decrease in superoxide dismutase (SOD), catalase sensitivity of gonadotropic cells to gonadotropin-releasing (CAT) and acid phosphatase (AP), and an increase in aspartate hormones, as well as gonadotropin secretion by elevating plasma transaminase (AST) and alanine transaminase (ALT). levels of glucocorticoids. These lead to the development of Additionally, the authors revealed the protective effects of gonad toxicity in animals and cause reduction in sperm number, antioxidants (vitamins C and E) against the cytotoxicity induced viability and motility (89). Ferreira et al . (97), in mice exposed by AlCl 3. Zatta et al . (86) analysed the effect of aluminum on orally to sodium arsenite (NaAsO 2) for a period of 35 days (a full aconitase protein in rats, which shows a significant decrease in cycle of spermatogenesis in mice), observed a significant the activity of this enzyme. Akonitase is a citrate-binding protein reduction in testicular mass (expressed as testes/body weight in the Krebs cycle, so decreasing its activity may result in ratio) compared to the control group (animals that did not reduced Krebs cycle performance and adversely affect the receive arsenic in their drinking water). Additionally, excessive mitochondria, which may be a potential cause of sperm injury - exfoliation of immature germ cells was observed in the lumen of decreased motility and viability. The studies of Klein et al . (87) seminal tubules. Significant damage to the epithelium and the on human semen show the presence of aluminum in sperm, presence of numerous intraepithelial vacuoles and reduced especially in men with oligozoospermia, where statistically motility of sperm were noted. Additionally, a massive 343 degeneration of germ cells, and alterations in the levels of LH, Cd. They revealed that Cd exposure substantially increased FSH and T were also reported (89). Disorders of hepatic MT (3.9-fold increase), but did not increase MT spermatogenesis by arsenic may also be related to its inhibitory translation in interstitial cells. The authors concluded that the effect on T, LH and FSH secretion by different varieties of germ inability to induce the metal-detoxicating MT-protein in response cells in the stage VII seminiferous epithelium cycle, as was to Cd, may account for a higher susceptibility of testes to Cd noted by Sarkar et al . (98) in rats during 26 days of toxicity and carcinogenesis, compared to the liver. intraperitoneally administrated sodium arsenite (at doses of 4 – A direct effect on the induction of reactive oxygen species by 6 mg/kg/day). Histological examination of arsenic-treated Swiss Cd has not been demonstrated. However, it has been shown that albino mice testes revealed a highly significant depletion in all by binding the sulfhydryl groups of glutathione (GSH), the germ cell populations such as spermatogonia A and B, cadmium may indirectly exacerbate the OS (108). In mouse primary and secondary spermatocytes, as well as spermatids studies, statistically significant lower antioxidant enzyme with respect to controls (99). Li et al . (100) revealed significant activity of CAT, SOD and peroxidase (POD) compared to the negative correlations between the concentrations of As, as well control group, after intraperitoneal administration of cadmium as Cu and Pb, and sperm concentrations. Moreover, they chloride (1 mg/kg b.w.), was demonstrated (109). Other animal observed that Cu, Mn, and Se concentrations were significantly studies also point to increased OS, decreased expression of higher in the infertile men than in the healthy subjects. These testicular antioxidant enzymes, sperm motility and sperm count findings provide evidence for relationships between human after the intraperitoneal administration of cadmium acetate at a semen quality and metal exposures (100). A substantial number dose of 0.025 mg/kg b.w. For 15 days (110, 111). Reduced of some environmental pollutants, such as heavy metals (arsenic, activity of steroidogenic enzymes 3 b- and 17 b-hydroxysteroid cadmium, lead, mercury), have been shown to disrupt endocrine dehydrogenase has also been noticed, which may contribute to function, and they can cause reproductive problems by the disturbance of T synthesis and thus promote disorders of decreasing sperm count and quality, increasing the number of spermatogenesis. Additionally, coexposure to Cd and Pb showed testicular germ cells and causing male breast cancer, more toxic effects to Cd exposition than Pb, while combined cryptorchidism, hypospadias, miscarriages, endometriosis, exposure demonstrated least toxicity (107). Metal-exposed impaired fertility, irregularities of the menstrual cycle, and groups showed significantly decreased testicular and epididymal infertility (101). sperm counts (112). Antioxidants such as vitamin C prevent changes in the activity of these enzymes caused by cadmium. Cadmium This indicates a significant effect of ROS on spermatogenesis processes (110). Cadmium (Cd) is a naturally occurring toxic heavy metal that Examination of the toxic effects of cadmium on somatic cells has a significant degree of accumulation in the organism. Target in mammalian testes showed that the blood-testes-barrier (BTB) organs are kidneys, liver, bones and male reproductive organs, was particularly sensitive to cadmium. In in vitro studies of but Cd has also been shown to possess the ability to accumulate Sertoli cell cultures, it was shown that cadmium is affected by in the hypothalamus and pituitary gland, decreasing the prolactin tight cell-to-cell junctions, probably via specific signal concentration, which also has influence on male fertility (102). transduction pathways and signaling molecules, such as p38 Cadmium is widely used in industry, which is the main source of mitogen-activated protein kinase (MAPK) (103). Other studies occupational exposure. Additional sources are a contaminated have also shown damage to seminiferous tubules by cadmium environment, food and daily consumer products, as well as chloride, resulting in the exfoliation of immature germ cells in the tobacco smoke (34). The daily diet intake amounts to about 1 lumen of the seminal tubules and inhibition of the proliferation of µg/day, while tobacco smokers provide an additional 1 – 3 µg piglet Sertoli cells (113). In rat studies it was shown that doses of daily (103). This has been confirmed in studies that showed 30 mg/L Cd administered orally for 90 days showed effects on higher (statistically significant) concentrations of cadmium in the sperm motility and abnormal percentages of sperm, which were blood of smokers than nonsmokers. A significant positive significantly lower when compared to the control group. The correlation was found between cadmium blood levels, number of percentage of motile spermatozoa and morphologically normal immotile spermatozoa, and theratozoospermia index (TZI) (104). sperm was markedly reduced (114). In a cross-sectional study in Cd exposure affects human male reproductive organs/system and the Chinese population, the concentration of cadmium in urine deteriorates spermatogenesis and semen quality, especially sperm and semen samples of men from the Reproductive Center of motility and hormonal synthesis/release. Exposure to Cd at low Tongji Hospital in Wuhan was examined. It was shown that doses has adverse effects on both human male and female urinary levels of cadmium were significantly negatively reproduction and affects pregnancy or its outcome (105). In correlated with progressive sperm motility and total motility. addition to chromium, Cd is the best known and most often Environmental exposure to cadmium, as well as other metals examined ME for hormonal activity. Cadmium has been shown (molybdenum and lead) significantly contribute to a decline in to activate the ER a receptor by interactions with the LBD region, human semen quality (115). Similar results were obtained by De probably by replacing the zinc ions in the area of the so-called Franciscis et al . (104), who measured cadmium concentration in zinc finger motif. Although the precise mechanism by which the blood and semen samples of healthy males. A significant cadmium activates ER a remains to be defined, it is possible that correlation between blood cadmium concentrations, cigarette interaction of the metal with amino acids located on helices H4, smoking, occupational exposure, and parameters of semen H8, and H11, and at the interface of the loop and helix H12 in the quality (number of non-motile spermatozoa, theratozoospermia ER a receptor structure, induces structural changes that mimic the index) was observed. The authors concluded that such a reduction structural changes induced upon the binding of estradiol. in spermiogenic function could be an early marker of a toxic Activation of the receptor leads to the expression of estrogen- effect of cadmium pollution. regulated genes and consequently an estrogenic effect without the Famurewa and Ugwuja (116) showed that cadmium in presence of the natural hormone (106). Ren et al . (107), to clarify seminal and blood plasma, as well as lead in blood plasma, were the molecular mechanism of Cd-induced toxicity in testes, significantly higher in azospermic and oligospermic men compared metallothionein (MT) gene expression, MT protein compared to normospermic men. However, while seminal accumulation, and Cd retention at different times in the freshly plasma lead was significantly higher in oligospermic and isolated testicular interstitial cells and liver of rats treated with normospernic men than in azospermic men, the seminal plasma 344 lead was comparable between oligospermic and normospermic In research conducted by Horky et al . (126) it was noticed that a men. They found significant inverse associations between blood group of animals (boars) supplemented with chromium and seminal cadmium levels and sperm count, motility and picolinate had significantly less disturbances in ejaculate morphology, but blood lead was inversely correlated with sperm parameters (sperm motility, ejaculate volume, sperm count only. The study suggests that environmental exposure to concentration and percent of pathological sperm) than the cadmium and lead may contribute to the development of poor control group (receiving only 31% of the daily demand for sperm quality and infertility in men of reproductive age in chromium in the diet). But the vast majority of studies indicate Nigeria (116). Davar et al . (117), in their clinical study, reveal excessive exposure to chromium and the associated OS as the that infertile smokers had disturbances in sperm morphology, cause of male fertility disorders, for example by inducing namely defective sperm heads, mid, and tail pieces, with high changes in sperm morphology and causing spermatogenesis slow motile sperm cells. Therefore, they rely on artificial disorders, as was shown in workers exposed in different conception methods, namely in vitro fertilization and gamete occupational settings around the globe. Higher levels of intra-fallopian transfer, however these procedures in most cases chromium (VI) exposure in the workers of some occupational result in abnormal foetal shape (117). Ranganathan et al . (118) settings enhance the OS, which may cause cellular and in their study also documented that the levels of cigarette molecular damage such as genotoxicity and chromosomal toxicants (including Cd) in semen were high, accompanied by aberration formations, as well as carcinogenic effects (125). low levels of anti-oxidants in the seminal plasma of infertile Bassey et al . (127) showed that the mean seminal plasma smoker subjects. In addition the investigation of Cd treated chromium level (measured by Atomic Absorption Spectrometry) sperm cells through a scanning electronic microscope showed of oligospermic and asthenooligospermic patients was mid piece damage to spermatozoa. Dispersive X-ray analysis to significantly higher in infertile men than in healthy, fertile men. identify the elemental composition further confirmed the The authors conclude that this high chromium concentration has presence of Cd. Finally, the in-silico analysis on semenogelin adverse effects on sperm production, motility and sperm count in sequences revealed the D-H-D motif which represents a infertile men. favourable binding site for Cd coordination. These studies In mouse studies, increased concentrations of OS parameters clearly indicated the influence of Cd on ROS, leading to in the testes was observed, as well as significantly decreased impaired sperm morphology, leading to male infertility (118). sperm count and markedly increased rates of sperm abnormality Recently, Huang at al . (119) examined the impact of some after a single intraperitoneal application of chromic acid (CrO 3) metals, such as Al, Cd, Cr, Mn, Ni, Pb, Se and Sb, in in a dose of 1 mg/kg b.w. (128). Similar results were obtained in coexposition to environmental particulate matter < 2.5 µm in studies on monkeys administered orally by potassium aerodynamic diameter (PM2.5), on the male reproductive health dichromate at concentrations of 50 – 400 ppm in drinking water. of a Chinese population. The authors revealed that an increase in There were definitely lesser sperm counts and sperm forward PM2.5 exposure was significantly associated with an 8.5% and motility. Additionally, the activity of antioxidant enzymes were 8.1% decrease in sperm concentration and total sperm number, reduced, in a dose- and duration-dependent manner. respectively. They also documented that antimony, cadmium, Simultaneously the administration of vitamin C significantly lead and nickel exposures were significantly associated with prevented the above-mentioned changes (129). Geoffroy- decreased sperm concentration. Huang at al . (119) concluded Siraudin et al . (130) developed the special experimental model that PM2.5 and certain constituents may adversely affect semen (culture of rat seminiferous tubules) examining the exact key quality, especially sperm concentration, and provide new phases of spermatogenesis (mitosis, meiosis and the initial evidence to formulate pollution abatement strategies for male stages of spermiogenesis), which are disrupted as a result of reproductive health. Cr(VI) action. The authors revealed an increasing amount of abnormal nuclei in a dose-dependent manner, which indicates Chromium that chromium compounds have an effect on prophylaxis and meiosis. Some studies also examined toxic testicular damage by Chromium (Cr) is widely present in the environment. Its Cr(V), which is generated as an intermediate metabolit from the toxicity depends on the valence. The IARC classifies chromium intracellular reduction of Cr(VI), and is also indicated as an (VI) as a proven human carcinogen. Chromium (III) is a cofactor agent of carcinogenesis. The subcutaneous administration of of many proteins with enzymatic activity, fats and Cr(V) complex ([CrV-BT] 2) into mice induced impaired carbohydrates. It is delivered mainly with the diet, or dietary permeability of the BTB, as was confirmed by histochemical supplements. Daily intake is approximately 40 – 240 µg/day examination of isolated seminal ducts. Significant damage to (120, 121). Exposure to hexavalent chromium refers primarily to Sertoli cells and germ cells, and irregular spermatoid features, as people with occupational exposure. It gets into the organism well as statistically significant reductions in acrosome integrity, primarily through the respiratory tract. The influence of were observed (131). In the light of an increasing number of chromium (VI) on the development of lung cancer and other used metallic nanoparticles and ions from cobalt-chromium respiratory system cancers has been proven (122). It has been (CoCr) alloy prosthesis, potential adverse effects were revealed, also shown that small reproductive organs are the target organs however, their biological effects on male reproductive function for chromium action (123). Chromium compounds are able to remain unclear. Examination of their effect on adult male rat generate free radicals, which have an indisputable role in reproduction after intraarticular injection of CoCr nanoparticles carcinogenesis. Their role in the development of hormone- at doses of 20 – 500 µg/kg b.w. for 10 weeks revealed dose- related diseases such as breast cancer is also well documented. dependent decreased sperm motility, number and viability. High Especially interesting is the interaction of estrogens with doses of nanoparticles, especially, could significantly reduce chromium as environmental toxins in free radical generation, epididymal sperm motility, viability and concentration, increase which participates in cancerogenesis (121, 124). abnormal sperm rate and levels of Co and Cr ions in serum and The carcinogenic effect of chromium (VI) is primarily due to in the testes, as well as induce testicular damage and its significant oxidoreductive properties. A high ability to induce pathological changes via OS (132). OS may also be related to the toxic effects of chromium on Chen et al . (133) evaluated the influence of metal ion reproduction (125). It has been proven that chromium deficiency exposure on semen quality in young male patients undergoing can also negatively affect semen quality in animals and humans. total hip arthroplasty using metal-on-metal (MoM) articulations. 345

Patients were sorted into MoM and metal-on-polyethylene between Co and Pb concentrations, sperm progressive motility, (MoP) groups with equal case numbers. Compared to a and normal morphology of spermatozoa (Co-negatively; Pb- preoperative baseline, patients in both groups had increased positively). A significant negative correlation between Cr cobalt and chromium concentrations in the blood and seminal concentration and slow progressive motility, and between CAT fluid after surgery. Between group comparisons at 6 months and activity and volume of ejaculate. Co, Cr, and Pb levels and CAT 1 year after surgery showed that patients in the MoM group both activity were also related to sperm characteristics and male had greater Co concentrations in blood and semen and greater Cr fertility. Co and Pb influence progressive motility and normal concentration in blood and semen. Patients receiving MoM morphology of human spermatozoa. Marzec-Wroblewska et al . prosthesis had a reduced percentage of morphologically normal (31) concluded that Co and Pb levels in semen may be a useful sperm, and decreases from the preoperative level (44.7%) were diagnostic in male infertility. significant at 6 months (36.8%) and 1 year (33.8%). The authors concluded that their data shows a significantly greater Copper concentration of metal ions in the blood and semen in patients with MoM prosthesis with a reduced percentage of Copper (Cu) is an extremely important microelement in morphologically normal sperm. However, despite small effects humans and plays a significant role in the metabolism. It occurs on sperm quality, some concerns remain (133). in many enzymes as an essential element to their action. Among others, Cu is a part of cytochrome C oxidase, a key enzyme Cobalt catalyzing the final step in the mitochondrial electron transfer chain, but also SOD. Depending on the concentration, copper Another important micronutrient is cobalt (Co), which is a may reduce or induce OS, which seems to be a very important key element of cobalamin (vitamin B 12 ). Daily dietary intake aspect of its action in the cells. Its protective role is connected ranges between 5 and 50 µg/day (134). Although it is not a with the fact that Cu is an element of the active center of SOD- cumulative toxin, chronic exposure induces negative effects on 1 (52). Tsunoda et al . (139) showed that deficiency of SOD-1 the organism (135). A mouse study revealed that exposure to causes a decrease in in vitro fertilization ability by intensifying cobalt during the perinatal and postnatal period affected body OS, reducing ATP levels and causing disorders of the tyrosine weight during puberty, but did not significantly reduce phosphorylation process. It also had a negative effect on sperm reproductive organ growth. However, the negative impact of motility in tested mice (Sod1-KO sperm in compared to wild- cobalt on later life cannot be ruled out, and cobalt might be type sperm). Cytochrome C oxidase is a key enzyme responsible considered as a possible risk factor for male reproductive health for normal sperm motility, through its role in the ATP (136). In studies on male Swiss mice exposed to (CoCl 2×6H 2O) production. The occurrence of a specific cytochorm C isoform in in drinking water for a period of 12 weeks, a significant the male gonadal cells, isoform VIb-2, has been reported (140). reduction in the number of fertilizations was demonstrated when In the organism, copper metabolism is primarily associated pairing with non-exposed females at a dose of 400 ppm and 800 with the ceruroplasmin, and it was shown that within the testes, ppm. Histopathological examination showed seminiferous approximately 80% of seminal ceruloplasmin is located in the tubules and interstitial tissue necrosis, Leydig cells hypertrophy Sertoli cells. Its direct or indirect impact on the structure and and spermatogonial cell degeneration. The authors also noted a function of male gonads and gametes is not yet completely decrease in epididymal weight at a dose of 800 ppm, a decrease understood. It also concerns iron ions, which together with Cu, in epididymal sperm count in three doses: 200, 400 and 800 are essential trace nutrients also playing important roles in ppm, as well as a reduction in daily sperm production in two human health and fertility. Excess or deficiency of either doses: 400 and 800 ppm (137). element may lead to defective spermatogenesis, reduced libido, The studies of Zeng et al . (138) have shown that urinary and oxidative damage of the testicular tissue and spermatozoa, metal concentrations directly or indirectly influence circulating ultimately leading to fertility impairment (141). Another testosterone production in Chinese men. Urinary concentrations important protein that helps maintain copper homeostasis in the of some selected metals ( e.g. arsenic, cadmium, cobalt, organism is metallothionein. The metallothionein isoform (MT- chromium, copper, lead, molybdenum, mercury, nickel, 1) is found in Sertoli cells and in spermatogenic cells, which selenium and zinc) and serum levels of T were analyzed in men indicates the important protective function of MT-1. The from an infertility clinic. Among the measured metals, the existence of this isoform was demonstrated in rat studies where median urinary Zn (359.36 µg/g creatinine) and Co (0.16 µg/g significantly higher MT-1 mRNA expression was demonstrated creatinine) concentrations were the highest and lowest, after subcutaneous cadmium injection (142). Moreover, metal respectively. Significant dose-response relationships were found replacement studies using an apo-polypeptide of the estrogen between decreased T and urinary Mn and Zn, even when receptor DNA-binding domain demonstrated that copper binds considering multiple metals. The authors concluded that to the ER-DBD with greater affinity than does zinc, confirming elevated Mn and Zn are inversely associated with T production. its action as a metalloestrogen (143). Marzec-Wroblewska et al . (31) analyzed cobalt (Co), Copper action as a ME was showed in animal and cell model chromium (Cr), and lead (Pb) concentrations in human semen studies (75). In human studies, a significant negative correlation and catalase CAT activity in seminal plasma, and the effects of between Cu concentration in seminal plasma and percentage of their relations on sperm quality. They examined the relationships sperm with normal morphology was demonstrated. The control and differences between Co, Cr, and Pb concentrations in group consisted of males exposed to copper as a result of local seminal plasma, CAT activity, and semen parameters. The contamination from the e-waste factory. The concentration of authors did not establish differences in Co, Cr, and Pb copper and other metals (Cr and Cd) was statistically higher than concentrations or CAT activity between normozoospermic men in the control groups, made up of residents of cities distant by and those with pathological spermiogram. However, they found 100 km (group 1 control) and 200 km (group 2 control) from the significantly lower Co concentrations and CAT activity in males contamination area (144). In research conducted by Li et al . with normal sperm motility than in asthenozoospermic males. (145) a significant negative correlation between Cu and sperm They found significantly lower Co and higher Pb concentrations concentration and motility was also found in Chinese men. in males with normal morphology of spermatozoa than in Almost half of the tested men had decreased fertility (based on theratozoospermic males. There were significant correlations sperm count and motility). The level of copper in the semen of 346 these males was statistically higher than in the group with related to the effects of anti-sperm antibodies. This phenomenon normal semen parameters. Some studies showed lower seminal is favored by damage to the testes structure under the influence of plasma Cu level in azoospermic males compared to healthy lead salt, among others BTB. Excessive agglutination may cause controls, leading to a concomitant decrease in SOD activity and the reduction of sperm motility (153). No impact on the integrity a higher risk of oxidative stress (146). of BTB, however, was observed in human studies, which could Recently Palanil et al . (147), determining the relationship of be explained by the lack of influence of spontaneous acrosomal the concentration of some metals (among others copper, lead, reactions, which are not induced by Ca 2+ ions. In Chinese men a chromium, selenium) present in seminal plasma with semen broad range of lead acetate concentration (0 – 100 µM) inhibits parameters and reproductive endocrine function in men in and human sperm functions by reducing the levels of sperm 2+ around Chennai (India), found that the most affected age group intracellular cAMP, [Ca( )i] and tyrosine phosphorylation of was 31 – 40. The mean value of the levels of the examined sperm proteins in a dose-dependent manner (150). Some authors metals present in seminal plasma were significantly higher in suggest the influence of lead on chromatin condensation azoospermia, asthenozoospermia, asthenoteratozoospermia, processes during spermatogenesis, by zinc replacement from oligoasthenozoospermia and oligoasthenoteratozoospermia protamine binding sites, reduction of chromatin stability and as a participants, when compared to normozoospermia participants, result reduction in sperm quality (154). and showed adverse effects on male infertility. Additionally the Studies on an animal model (crab Sinopotamon henanense ) authors concluded that lifestyle changes and associated factors exposed to lead indicate that this metal probably disturbs have a high impact on the incidence of male infertility among calcium homeostasis through interaction with calcium channels and around the Chennai population. (as indicated by experience with verapamil-calcium channel blockers, compared to controls). Exposure of Pb tested animals Lead caused a decrease in acrosomal response, increased oxidative stress (increased protein carbonylation (PCO) and Lead (Pb) shows well known significant toxicity for living malonyldialdehyde (MDA) concentration), weaker integration organisms. It has neurotoxic and nephrotoxic effects, and causes of sperm DNA and reduced viability of sperm. Under the damage to bones, digestive and immune systems. The main route influence of lead, the intracellular concentration of calcium and of exposure is the alimentary route, but occupational exposure activity of acrosine decreased, and the activity of calmodulin by inhalation is also important (148). The concentration of Pb in was reduced (calcium ions are required to activate calmodulin exposed workers should not exceed 30 µg/dL, while the and change its conformation) (155). Similarly, the impact of permissible level for unexposed adults should be lower than 25 lead, as well as cadmium, on seminal parameters in idiopathic µg/dL. Lead has a high capacity for accumulation in the oligoasthenozoospermic infertile males was observed. Pb organism, and also in the male reproductive system, especially in reduces the mobility of sperm and progressive motility and, the epididymis, prostate, seminal fluid and vesicular seminalis, importantly, significant positive correlations were observed which may explain the damage to sperm motility. Leydig cells between seminal lead and cadmium levels and percentage of are particularly susceptible to lead, which contributes to sperm DNA fragmentation, and semen ROS level in infertile impaired T synthesis and consequently to disorders of men (156). In He et al . (150) in vitro studies, samples of human spermatogenesis (149). Pb preferentially accumulates in male semen were exposed to various lead acetate concentrations. reproductive organs and can be up to 10 µM in human seminal They revealed that treatment with 10 – 100 µM lead acetate plasma, and impairs mammalian spermatogenesis and sperm reduces sperm mobility in a dose-dependent manner, and also quality in vivo . It also inhibits sperm functions in vitro, but the managed to slow down capacitation and acrosomal response. underlying mechanisms remain unclear (150). Sperm motility Decreased motility may be caused by a decrease in the and sperm morphology are considered to be particularly intracellular concentration of the cAMP - the second sensitive to lead influence. This was confirmed in a study, in intracellular messenger (by inhibition of adenylyl cyclase), as which rats were treated orally by lead acetate (6 mg/kg) for 8 well as by reduction of intracellular Ca 2+ ion levels, and weeks. Significantly smaller sperm counts, decreased motility inactivation of tyrosine kinase, which may result in effects on and abnormal sperm morphology (expressed as percentage of sperm function (150). Pant et al . (157) showed that semen lead sperm with abnormal morphology) were noticed. Also, increased and cadmium values were significantly higher in infertile oxidative stress has been demonstrated, expressed as: reduced subjects. A negative association between concentration of these level of GSH, increased hydrogen peroxide (H 2O2) and LPO metals and sperm concentration, sperm motility and percentage (lipid peroxidation products) in nuclear tissue homogenates, of abnormal spermatozoa was found. Authors showed that indicating the ability of lead to induce OS in infertile men (151). exposure to Pb and cadmium in environmental concentrations In other studies conducted on male mice divided into 3 groups: might affect the semen profile in men. Additionally, age, diet, an untreated group, a low-dose group (50 µg/kg b.w.) and a high- smoking and tobacco chewing habits may have an influence on dose group (100 µg/kg b.w.), received lead acetate in drinking the increase in exposure to Pb and Cd in the individual subjects. water for 16 weeks, and a statistically significant increase in the percentage of immobile sperm in the treated groups was Molybdenum observed, when compared to the control group. Significant reduction in the number of live sperm in both doses of Pb and Molybdenum (Mo) although is one of the least common mean sperm concentration in the high-dose group was also elements on Earth, plays an important role in the proper noticed. The amount of immotile sperm, the percentage of DNA functioning of the human organism, being among others a fragmentation and the percentage of sperm degradation also cofactor of many enzymes. It is a microelement which is the significantly increased. The most common type of sperm active center of about 50 enzymes, including xanthine oxidase degradation was sperm with a small halo, as was shown by and aldehyde oxidase, and it is also a catalyst for redox reactions sperm chromatin dispersion (SCD), the method used for in the body. The daily requirement is set at 100 – 300 µg/day detection of sperm DNA fragmentation, however, no significant (158). The main route of exposure to this metal is oral differences were noticed between analysed groups (152). absorption. It is also used in various industries, which cause Some authors showed an increased amount of agglutinated excessive exposure to this element. The role of Mo as a sperm in infertile men, and indicated that agglutination may be xenoestrogen has been described, but the exact mechanism of 347

the harmful effects of molybdenum on male reproduction is (MoO 3) nanoparticles were the least (166). Molibdenum, in unknown and data are not uniform (34). addition to cobalt and chromium, is a component of stainless In studies on the development of mouse embryos, steel intramedullary nails (IMN). Studies conducted by preimplantation cultured in vitro , exposed for 5 days of sodium Elsamanoudy et al . (167) among men with IMN showed a molybdate at a different doses (from 0 to 160 mg/mL), a dose- statistically significant inverse relationship between the dependent negative effect was revealed. No negative effects concentration of these metals in seminal plasma and sperm were observed at small doses, but at doses of 40 µg/mL and parameters (progressive motility, concentration and higher, the cleavage of blastocyst and delivery birth rates morphology). Additionally, a statistically significant decrease in significantly decreased, and a significantly increased proportion Bcl-2 spermatozoal expression (antiapoptotic protein), a higher of degenerated blastocysts were revealed (159). This was Bax expression (proapoptotic protein) and lower Bcl-2/Bax confirmed in studies on mice, during 14 days of oral ratio in subjects with IMN for ³ 5 years than in controls were molybdenum administration with water (in the form of sodium observed. The authors indicated that spermatozoal Bcl-2/Bax molybdate dihydrate) at different doses (from 0 to 200 mg/L). It ratio could be used as a candidate biomarker of reproductive was shown that molybdenum in smaller doses of 25 mg/L disorders in individuals with IMN (167). improved the sperm quality of the tested mice, but at the lowest doses did not show any effect. However, in higher doses, a Mercury significant negative effect was noted on the epididymis index, sperm motility, concentration and abnormality rate. Additionally, The influence of mercury (Hg) on human fertility has been reduced activity of SOD and GPx, as well as increased MDA studied for a long time. In 1985, Lauwerys et al . (168) assessed concentrations, have been shown, which may indicate increased the fertility of male workers exposed to mercury vapor or OS, especially at the highest doses (160). In experimental studies manganese dust. Hg concentration in the urine of employees was with rabbits fed commercially available food contaminated with determined, and survey data on the number of offspring was molybdenum, an increased number of abnormal spermatogenic collected. In the range of Hg concentrations: 5.1 to 272.1 mg/g cells of seminiferous tubules and large sized syncytial cells were creatinine, obtained during the study of workers, the significant found, while the number of mature spermatocytes decreased difference between the number of observed children and a well- significantly. The generation of free radicals, due to the high chosen control group, which was expected based on dietary Mo intake, resulting in a marked increase of creatine reproductive experience, did not appear. However, such kinase (CK) activity was indicated as the main way of action dependence was observed for exposure to manganese vapors. On (161). Whereas in a multigenerational study of rats exposed to the contrary Keck et al . (169) studied a 25-year-old man with molybdenum in the form of dihydrate (0.5 – 40 mg/kg b.w./day) unexplained infertility, who had been employed in a chemical for a period of 90 days, no changes in sperm parameters in the factory and exposed for 5 years to chloralkali-electrophoresis, male subjects were observed. Additionally, the value of the and revealed high mercury concentrations in hair, blood, and NOAEL (No Observable Adverse Effect Level) for reproductive urine samples, considerably above the levels of unexposed toxicity (gonadal, sperm and estrus cycle effects) was controls. Semen analysis of these patients showed azoospermia established at 60 mg Mo/kg b.w./day, and at 17 mg Mo/kg or severe oligoasthenotheratozoospermia, with elevated serum b.w./day for systemic toxicity (162). FSH levels. The toxic action of Hg was confirmed by In cross-sectional observational data conducted by Zeng et autometallographic analysis of the bilateral testicular biopsies, al . (163) on Chinese men, patients at an infertility clinic, and the which revealed silver-enhanced mercury grains, primarily in the influence of 13 different metals (As, Cd, Co, Cr, Cu, Fe, Pb, Mn, interstitial Leydig cells. In a case-control study Choy et al . (170) Mo, Hg, Ni, Se, Zn) on parameters reflecting semen quality showed that higher seafood consumption was associated with (sperm concentration, count, motility, normal morphology, and elevated blood mercury concentrations, which are connected abnormal head) did not show any correlation between Mo with male and female infertility. The above observation was concentration in urine and decreased semen quality, but potential confirmed in animal studies. Significant adverse effects were adverse exposition to nickel and selenium was indicated. The noted on male rat reproduction endpoints, including fertility authors suggest that further epidemiological studies were needed (time to impregnate the females and a lower rate of to obtain data on long-term exposure to these metals. Somewhat impregnation), as a result of exposure to HgCl 2, even at a dose different results were obtained by Meeker et al . (164), who that was not clinically toxic. Additionally, a lower correlation examined the urinary levels of 18 different metals, including between testicular T levels and subsequent exposure days, as essential and nonessential elements (among others As, Cd, Cr, well as a lower sperm count in the epididymis head and body of Cu, Pb, Mn, Hg, Mo, Se, Zn) in infertile men regarding their the exposed males was documented (171). In another cross- connection with semen quality parameters. The authors suggest sectional study the influence of environmental mercury exposure that environmental exposure to molybdenum, cadmium and lead on semen quality and reproductive hormones in men living in the may significantly contribute to a decline in human semen Greenlandic Inuit, and a European region (Poland and Ukraine) quality, however they concluded that further research is needed were not exactly confirmed. No significant association was in order to obtain knowledge about the exact mechanism of found between blood concentrations of mercury and the molybdenum toxicity (164). characteristics of semen parameters (semen volume, total sperm Recently, attention has been paid to nanomaterials count, sperm concentration, morphology and motility) and (nanotubes, nanowires, fullerene derivatives (buckyballs), and reproductive hormone levels (free androgen index (FAI), FSH, quantum dots), which can be also considered as a source of LH, T) in any region (172). toxicants, due to the lack of information concerning their impact on human health and the environment. Studies on the Nickel cell lines of mouse spermatogonia showed a concentration- dependent toxicity for all types of particles tested, whereas the Due to the wide use of nickel (Ni) in industry, it is a appropriate soluble salts had no significant effect (165). widespread element in the environment. It has also been proven Additionally, results demonstrate cell membrane dysfunction that nickel accumulates in the testes. Its toxicity has been after exposure to 5 µg/mL and 10 µg/mL of Mo, but silver identified in animal studies, for example in rats, where the effect nanoparticles were the most toxic, while molybdenum trioxide of nickel exposure in the form of nanoparticles given orally has 348 been examined (173, 174). The effect of nickel on sperm motility velocity (VSL), and average path velocity (VAP). Previously has been demonstrated, and a significant reduction in FSH and T Saaranen et al . (184) revealed that selenium accumulates in the levels in male rats was noted (175). Histopathological testes, as evidenced by the much higher level of this element in examination also revealed pathological changes in the testes seminal plasma than in the urine of the studied men. (immature germ cells in the lumen of seminiferous tubules, Hawkes et al . (185) in their study documented that Se epithelial cell shedding and abnormal cell distribution in the supplementation had no effect on sperm Se, serum androgen seminal tubule), and intensification of the apoptosis process in concentrations, sperm count, motility, progressive velocity, or the group of animals treated with nickel (173). A positive morphology. They observed progressive decreases in serum significant correlation was shown between the concentration of luteinizing hormones, semen volume, and sperm Se in both the nickel in the blood and the percentage of tail defects in male high-Se and placebo groups. Moreover, sperm straight-line sperm compared to the control group (176). velocity and percentage of normal morphology increased in Se- Zafar et al . (177) investigated a male Pakistani population treated and placebo-treated participants. The lack of increase in and found that Cd and Ni showed significant differences among sperm Se suggests that testicular Se stores were unaffected, even three monitored groups (normozoospermia, oligozoospermia though the participants’ dietary Se intake was tripled and their and azoospermia). Ni and Cd concentrations in the seminal total body Se was approximately doubled by supplementation plasma were negatively correlated with sperm concentration and (185). Eroglu et al . (186) showed a positive correlation between motility. This study suggested that exposure of Ni and Cd was serum and semen Se levels, and Se levels were found to be mainly related to the consumption of contaminated dietary significantly lower in infertile than fertile men. In this study, items, including ghee (cooking oil), flour and other agri- higher levels of serum and seminal plasma Se were detected in products. In some semen samples, the concentrations of Sn, V, the normozoospermia group when compared with the mild and Cu, Pb, Cr and Hg exhibited high levels, suggesting recent severe oligozoospermia groups. The severity of oligozoospermia human exposure to surrounding sources. In Pakistani semen was found to increase as Se levels decreased accordingly. samples, the levels of trace metals were lower and/or Additionally, levels of serum Se were correlated positively with comparable to those found in the populations of other countries levels of seminal plasma Se, suggesting that higher levels of Se (177). Zeng et al . (163) examine the association between urinary in serum directly affect levels of seminal Se. Furthermore, a metal concentrations, e.g. As, Cd, Co, Cr, Cu, Pb, Mo, Hg, Ni linear correlation was observed between decreasing sperm and Se, and semen quality parameters (sperm concentration, motility and decreasing levels of serum and seminal Se. These count, motility, normal morphology, and abnormal heads) in a findings suggest that serum Se levels affect sperm concentration Chinese population. The authors suggest that, among other and motility. The results of Eroglu et al . (186) study suggest that factors, Ni exposure may be associated with deteriorated sperm low levels of serum Se accompany low levels of seminal Se, morphology, and that Se exposure may be associated with better which in turn negatively affect sperm quality and lead to semen quality. Zhou et al . (178) studied the associations between idiopathic male infertility. Safarinejad et al . (187) have also urinary metal concentrations and sperm DNA damage, and they reported that Se supplementation increases serum and seminal found that urinary Hg and Ni were associated with increasing levels of Se. In parallel with the results of Eroglu et al . (186) trends for DNA tail length, and that urinary Mn was associated study, these findings suggest that Se deficiency in serum leads to with an increasing trend for DNA tail distributed moment. These Se deficiency in seminal plasma, causing poor sperm quality and associations did persist, even when considering multiple metals. male infertility. Another finding presented by the authors was Our results suggest that environmental exposure to Hg, Mn, and that both serum and seminal levels of Se were correlated Ni may be associated with increased sperm DNA damage (178). positively with sperm morphology (186). Marzec-Wroblewska et al . (179) analysed sodium (Na), Selenium copper and selenium levels in human semen and GPx in seminal plasma, and examined their correlations with sperm quality. Se Selenium (Se), similarly to copper, is considered an concentration (but not sodium or copper) and GPx activity were important element in maintaining the reproductive health of significantly higher in normozoospermic males than in those men, among other factors, because of its role as an antioxidant with a pathological spermiogram, and also in males with correct (179). It was indicated in animal studies that supplementation sperm motility and normal sperm morphology rather than in with Se (6 µg/kg b.w. in organic form) and vitamin E (5 mg/kg asthenozoospermic and theratozoospermic males. The authors b.w.) after 60 days positively affected semen parameters in dogs: observed the presence of significant correlations between sperm an increased percentage of sperm with normal morphology, motility, Se and GPx, between rapid progressive motility and concentration of spermatozoa, their viability and motility were Cu, between sperm motility and Na, between normal sperm noticed. The antioxidative activity in spermatozoa also increased morphology and Se and Cu, and between sperm concentration (expressed as increased activity of GSH-Px and TAC) (180). In and Cu and GPx. Moreover, they found significant correlations studies on buffalo bulls, a positive effect of selenium between Na and Cu, between Na and Se and between Cu and Se supplementation (10 mg Sel-Plex® twice weekly) on parameters in human semen in relation to alcohol consumption and tobacco such as percentage of viable sperm and T levels was observed, in use (179). comparison to the control group (not supplemented) (181). In studies on varicocelized male Wistar rats, the protective effect of Vanadium the oral administration of sodium selenite (at doses from 0.05 to 0.4 mg/kg b.w.) on testicular damage was demonstrated. Vanadium (V) is an element to which exposure mainly Improved parameters of sperm quality, decreased activity of occurs through inhalation and the alimentary route. It is released CAT, GPX and SOD, increased levels of MDA, and improved into the atmosphere in the process of the combustion of fuels. damage in testicular architecture were observed in varicocelized Due to industrial development, its intake is significant, rats, without changes in these parameters in normal rats (182). In especially in some particular areas. The level of 1.8 mg/day is a larger quantities, however, selenium may adversely affect male tolerated daily intake and is considered an essential metal. fertility. Selenium negatively influences semen quality in human Excessive supply of V, however, causes serious disorders studies, as was shown by Wan et al . (183). The authors showed associated, amongst others, with hepatotoxicity, nephrotoxicity, a reversed relationship between Se in seminal plasma and linear neurotoxicity and reproductive toxicity (188). It is believed that 349 the above changes are mainly related to the induction of OS. occupationally exposed men, measurements of heavy metals in This was confirmed by studies conducted on rats treated with the seminal fluid may be more predictive of below-reference sodium metavanadate (1 mg/kg b.w. for 90 days period). An sperm quality parameters than in blood (194). increased testicular level of MDA as well as lower testicular Information about tin (Sn) is provided by the study SOD and CAT activity were observed, but the administration of conducted by Guzikowski et al . (175), who revealed significant G-hesperidin, as an antioxidant, reduced the severity of these correlation between Sn level in seminal plasma and sperm count changes. Additionally, it was shown that vanadium exposure of men living in infertile couples. There was also a statistically causes a significant reduction in sperm count, viability, serum T significant difference between the concentration of Sn in seminal level, and an increase in the number of sperm cells with plasma in two subgroups: men with reference semen parameters abnormal morphology and histopathological changes in the and men with low semen quality. The exact mechanism of Sn testes as compared to the control group. It was also noted that reproductive toxicity is not yet known. Ghaffari et al . (195) fragmented DNA of sperm, expressed as DNA fragmentation examined in vitro effects of few metals ( e.g. Hg, Pb, Sn) on index (sDFI), was significantly higher than in the control group. sperm creatine kinase activity, and revealed that this studied The authors indicated that vanadium exposure caused reduced metal ions (at levels of 60 mg ml-1), may reduce normal sperm bioavailability of androgens to the tissue and increased free metabolism by inhibition of sperm creatine kinase, which radical formation, thereby causing structural and functional probably is an important cause of infertility in men. Guzikowski changes in spermatozoa (189). et al . (175) found that tin and cadmium levels were correlated Fortoul et al . (190) showed that inhalation exposure to with sperm count, but not with sperm motility and morphology vanadium pentoxide (V 2O5) at 3.64 g/h for a 12-week period in in ejaculates of men with limited fertility potential. Additionally the tested mice caused necrotic changes in Sertoli cells and the significant differences between infertile and spermatocytes, as well as changes in tight junctions in BTB normozoospermic groups for cadmium and tin levels in semen (pseudoinclusions were observed). The authors indicate tight were observed (175). Wang et al . (196) showed that junctions as a possible point of grip for V and oxidative stress environmental exposure e.g. to tin, nickel and molybdenum may induced by V. In human studies it was demonstrated that be associated decreased total T or total T/LH ratio. They found seminal plasma vanadate levels were significantly negatively significant inverse dose-dependent trends of urinary tin quartiles correlated with serum levels of total T and free T. There was with total T, as well as tin, nickel and molybdenum with the ratio also a significant positive correlation between seminal plasma of total T/LH ratio, but there were no significant associations V level and estradiol serum level. Lower hormone levels in men between urinary metals and sperm DNA damage (196). may be caused by damage to Leydig cells and inhibition of hormone synthesis such as: D53b- and 17 b-hydroxysteroid Conclusions dehydrogenase (HSD) as demonstrated in animal studies (191). Other in vitro and in vivo studies demonstrated that vanadium In the XXI century exposure to metals is a very serious treatment resulted in a significant disturbance of problem in highly developed countries mainly due to their wide oxidative/antioxidative balance. With the increase of testicular use, as well as their long half-life and also their ability to lipid peroxidation, marked lowering of SOD and CAT activities, accumulate in the organism. Despite the well-known harmful decreased sperm count, and substantially inhibited activities of effects of such elements as e.g. cadmium or lead on many D53b- and 17 b-hydroxysteroid dehydrogenase, as well as serum organs, further research is still needed to explore the detailed T level were observed. Importantly, all these changes were mechanisms of their action on the physiology of reproductive dose- and time-dependent. This suggests that during vanadium organs. Many metalloestrogens exert a wide variety of adverse exposure testes may be more susceptible to oxidative damage effects on reproduction and development, including influence on leading to their functional inactivation, as was confirmed male subfertility or fertility. Their action depends on several histopathologically (192). factors, such as timing and duration of exposure, distribution and accumulation in various organs, and on interference with Others specific developmental processes. This study is an attempt to systematize knowledge about the Only single sources of information are available about other role of metalloestrogens on male fertility, particularly current metalloestrogens, and all of them are described below. knowledge concerning environmental factors. Not all studies can Giaccio et al . (193) in an Italian population examined the be performed on humans, therefore animal models and cell influence of heavy metal pollution (inter alia antimony - Sb) as culture investigations are very helpful for understanding the possible candidates for influencing human semen quality, due to molecular mechanisms of xenoestrogens actions, reflecting their effects on ejaculate quality in men living in metropolitan areas, possible influence on the human organism. The mechanism of at a continued exposure to low doses. The authors revealed a the action of metals is diverse, but due to the possibility of strong correlation between abnormal Sb concentrations and men influence on the estrogen receptors’ function they are commonly with poor semen quality (disturbances in semen volume, sperm called metalloestrogens. Some of them can exert effects over the concentration, sperm total count, sperm motility, pH). The estrogen receptors, but not all, and many metals were not even results show a strong correlation between anomalous Pb and Sb investigated. Others act indirectly by modulation of estrogen concentrations and men with poor semen quality (193). receptors in different ways, but the mechanism of action of In recent research conducted by Sukhn et al . (194), it was others is mainly related to ROS generation and OS induction. shown that the concentration of barium (Ba) in seminal fluid is They can influence male fertility on many levels. An interesting, significantly higher in the group of examined men with but still not well-studied area, is the examination of possible abnormal sperm parameters compared to men with normal interactions between individual metals and estimation of their sperm parameters during environmental exposition to this metal. actions, especially at lower concentrations, because most studies The authors found that participants with low-quality semen had concern exposition to high levels of metals. Additionally, a significantly higher Cd and Ba concentrations in the seminal polymorphism of genes encoding some proteins with enzyme fluid than participants with normal-quality semen. They also activity ( e.g. metal ions as cofactors) or proteins transporting observed significant associations between low sperm viability some metal ions ( e.g. metallothionein) is worthy of further and higher blood Cd and Ba. The authors concluded that in non- investigation. The mechanisms of action of most 350 metalloestrogens on male reproductive health seem to be similar 10. Rolland M, Le Moal J, Wagner V, Royere D, De Mouzon J. and common to all of those described in our review. This is also Decline in semen concentration and morphology in a sample indicated by a study conducted by various research teams, of 26,609 men close to general population between 1989 and analyzing panels of many xenoestrogens in parallel. Awareness 2005 in France. Hum Reprod 2013; 28: 462-470. of the effects of these toxic ubiquitous metals on male 11. Sengupta P. Current trends of male reproductive health reproduction is important, but further studies are required to disorders and the changing semen quality. Int J Prev Med expand our basic knowledge, resolve inconsistencies, and assess 2014; 5: 1-5. the consequences on male fertility of exposure to metal ions, 12. Sengupta P, Dutta S, Krajewska-Kulak E. The disappearing especially concerning the effects of low exposition, which is sperms: analysis of reports published between 1980 and more often observed in daily life. 2015. Am J Mens Health 2017; 11: 1279-1304. Due to the fact that many studies are available in various 13. Asklund C, Jorgensen N, Skakkebaek NE, Jensen TK. databases on the effects of xenoestrogens’ action on male fertility, Increased frequency of reproductive health problems among and new reports are constantly being published, we decided to fathers of boys with hypospadias. Hum Reprod 2007; 22: limit the number of those analyzed, taking into account that it is 2639-2646. doi: 10.1093/humrep/dem217. not possible to analyse and include all the available information. 14. Kratz EM, Piwowar A. Melatonin, advanced oxidation An additional limitation of this study is the lack of detailed protein products and total antioxidant capacity as seminal statistical analysis of the collected literature data, so further meta- parameters of prooxidant-antioxidant balance and their analysis will be interesting and helpful in understanding the connection with expression of metalloproteinases in context impact of xenoestrogens, both environmental and occupational, of male fertility. J Physiol Pharmacol 2017; 68: 659-668. which will enable the introduction of the appropriate preventative 15. Shanle EK, Xu W. Endocrine disrupting chemicals targeting strategies, to avoid these harmful actions. estrogen receptor signaling: identification and mechanisms of action. Chem Res Toxicol 2011; 24: 6-19. Authors’ contribution : All authors participated in developing 16. Slowikowska-Hilczer J. Xenobiotics with estrogen or of the conception, contributed to writing the manuscript and antiandrogen action - disruptors of the male reproductive gave their final approval of the submitted version. system. CEJMed 2006; 1: 205-227. 17. Sidorkiewicz I, Zareba K, Wolczynski S, Czerniecki J. Acknowledgements : This work was supported by the Endocrine-disrupting chemicals-mechanisms of action on Wroclaw Medical University under Grant - ST.D180.18.004 and male reproductive system. Toxicol Ind Health 2017; 33: ST.D160.18.009. 601-609. 18. West MC, Anderson L, McClure N, Lewis SE. Dietary Conflict of interests: None declared. oestrogens and male fertility potential. Hum Fertil 2005; 8: 197-207. 19. Zoeller RT, Brown TR, Doan LL, et al . Endocrine-disrupting REFERENCES chemicals and public health protection: a statement of principles from The Endocrine Society. Endocrinology 1. Barratt CL, Bjorndahl L, De Jonge CJ, et al . The diagnosis 2012; 153: 4097-4110. of male infertility: an analysis of the evidence to support the 20. Zamkowska D, Karwacka A, Jurewicz J, Radwan M. development of global WHO guidance-challenges and future Environmental exposure to non-persistent endocrine research opportunities. Hum Reprod Update 2017; 23: 660- disrupting chemicals and semen quality: an overview of the 680. current epidemiological evidence. Int J Occup Med Environ 2. Katz DJ, Teloken P, Shoshany O. Male infertility - the other Health 2018; 31: 377-414. side of the equation. Aust Fam Physician 2017; 46: 641-646. 21. Sweeney MF, Hasan N, Soto AM, Sonnenschein C. 3. Hayden RP, Flannigan R, Schlegel PN. The role of lifestyle in Environmental endocrine disruptors: Effects on the human male infertility: diet, physical activity, and body habitus. Curr male reproductive system. Rev Endocr Metab Disord 2015; Urol Rep 2018; 19: 56. doi: 10.1007/s11934-018-0805-0. 16: 341-357. 4. Olesen IA, Joensen UN, Petersen JH, et al . Decrease in 22. McLachlan JA. Environmental signaling: from semen quality and Leydig cell function in infertile men: a environmental estrogens to endocrine-disrupting chemicals longitudinal study. Hum Reprod 2018; 33: 1963-1974. and beyond. Andrology 2016; 4: 684-694. 5. Minguez-Alarcon L, Williams PL, Chiu YH, et al . Secular 23. Nordkap L, Joensen UN, Blomberg Jensen M, Jorgensen N. trends in semen parameters among men attending a fertility Regional differences and temporal trends in male center between 2000 and 2017: identifying potential reproductive health disorders: semen quality may be a predictors. Environ Int 2018; 121: 1297-1303. sensitive marker of environmental exposures. Mol Cell 6. Olejnik B, Kratz EM. Lifestyle and male infertility. In: Endocrinol 2012; 355: 221-230. Health Promotion, Prevention and Care in Chronic Diseases 24. Jeng HA, Huang YL, Pan CH, Diawara N. Role of low - Modern Problems [in Polish]. A. Abramczyk, et al . (eds). exposure to metals as male reproductive toxicants. Int J Part 1, Wroclaw, A&A Optimed, 2011, pp. 161-169. Environ Health Res 2015; 25: 405-417. 7. Cooper TG, Noonan E, von Eckardstein S, et al . World 25. Hutz RJ, Carvan MJ, Larson JK, et al . Familiar and novel Health Organization reference values for human semen reproductive endocrine disruptors: xenoestrogens, dioxins characteristics. Hum Reprod Update 2010; 1693: 231-245. and nanoparticles. Curr Trends Endocinol 2014; 7: 111-122. https://doi.org/10.1093/humupd/dmp048 26. Amiri G, Valipoor A, Parivar K, et al . Comparison of 8. Esteves SC. Novel concepts in male factor infertility: toxicity of CdSe: ZnS quantum dots on male reproductive clinical and laboratory perspectives. J Assist Reprod Genet system in different stages of development in mice. Int J 2016; 33: 1319-1335. Fertil Steril 2016; 9: 512-520. 9. Carlsen E, Giwercman A, Keiding N, Skakkeblek NE, 27. Muselin F, Cristina RT, Igna V, Dumitrescu E, Brezovan D, Skakkebsk NE. Evidence for decreasing quality of semen Trif A. The consequences of aluminium intake on during past 50 years. BMJ 1992; 305: 609-613. reproductive function in male rats: a three-generation study. Turk J Med Sci 2016; 46: 1240-1248. 351

28. Dobrakowski M, Kaletka Z, Machon-Grecka A, et al. The in contemporary medicine [in Polish]. Przegl Lek 2005; 62: Role of oxidative stress, selected metals, and parameters of 908-915. the immune system in male fertility. Oxid Med Cell Longev 49. Carreau S, Lambard S, Delalandem C, Denis I, Bilinska B, 2018; 2018: 6249536. doi: 10.1155/2018/6249536. Bourguiba S. Aromatase expression and role of estrogens in 29. Hashemi MM, Behnampour N, Nejabat M, Tabandeh A, male gonad: a review. Reprod Biol Endocrinol 2003; 1: 35. Ghazi-Moghaddam B, Joshaghani HR. Impact of seminal doi: 10.1186/1477-7827-1-35 plasma trace elements on human sperm motility parameters. 50. Li X, Li H, Jia L, Li X, Rahman N. Oestrogen action and Rom J Intern Med 2018; 56: 15-20. male fertility: experimental and clinical findings. Cell Mol 30. Waheed MM, Meligy AMA, Dhalam SA. The relationship Life Sci 2015; 72: 3915-3930. between seminal plasma and serum trace elements and 51. Weiss J, Bernhardt ML, Laronda MM, et al . Estrogen actions semen parameters of dromedary camels (Camelus in the male reproductive system involve estrogen response dromedarius). Reprod Domest Anim 2018; 53: 1367-1374. element-independent pathways. Endocrinology 2008; 149: 31. Marzec-Wroblewska U, Kaminski P, Lakota P, et al . Human 6198-6206. sperm characteristics with regard to cobalt, chromium, and 52. Sikka SC, Hellstrom WJ. Bioenvironmental Issues Affecting lead in semen and activity of catalase in seminal plasma. Men’s Reproductive and Sexual Health. Academic Press, Biol Trace Elem Res 2019; 188: 251-260. 2018, pp. 293-304. 32. Stoica A, Katzenellenbogen BS, Martin MB. Activation of 53. Knez J. Endocrine-disrupting chemicals and male estrogen receptor-alpha by the heavy metal cadmium. Mol reproductive health. Reprod Biomed 2013; 26: 440-448. Endocrinol 2000; 14: 545-553. 54. Slomczynska M. Xenoestrogens: mechanisms of action and 33. Rehman K, Fatima F, Waheed I, Akash MS. Prevalence of some detection studies. Pol J Vet Sci 2008; 11: 263-269. exposure of heavy metals and their impact on health 55. Lazari MF, Lucas TF, Yasuhara F, et al . Estrogen receptors consequences. J Cell Biochem 2018; 119: 157-184. and function in the male reproductive system. Arq Bras 34. Wirth JJ, Mijal RS. Adverse effects of low level heavy metal Endocrinol Metabol 2009; 53: 923-933. exposure on male reproductive function. Syst Biol Reprod 56. Farooq A. Structural and functional diversity of estrogen Med 2010; 56: 147-167. receptor ligands. Curr Top Med Chem 2015; 15: 1372-1384. 35. Pizent A, Tariba B, Zivkovic T. Reproductive toxicity of metals 57. Zhang L, Cui S. Effects of daidzein on testosterone synthesis in men. Arh Hig Rada Toksikol 2012; 63 (Suppl. 1): 35-46. and secretion in cultured mouse Leydig cells. Asian-Aust J 36. Darbre PD. Metalloestrogens: an emerging class of Anim Sci 2009; 22: 618-625. inorganic xenoestrogens with potential to add to the 58. Combarnous Y. Endocrine disruptor compounds (EDCs) and oestrogenic burden of the human breast. J Appl Toxicol agriculture: the case of pesticides. CR Biol 2017; 340: 406-409. 2006; 26: 191-197. 59. Rasmussen MK, Ekstrand B, Zamaratskaia G. Regulation of 37. Prins GS. Endocrine disruptors and prostate cancer risk. 3b-hydroxysteroid dehydrogenase/ D5- D4 isomerase: a Endocr Relat Cancer 2008; 15: 649-656. review. Int J Mol Sci 2013; 14: 17926-17942. 38. Guzik A, Sawicka E, Dlugosz A. The role of estrogens and 60. Sheikh IA, Turki RF, Abuzenadah AM, Damanhouri GA, anvironmental factors in prostate cancer [in Polish]. Bromat Beg MA. Endocrine disruption: computational perspectives Chem Toksykol 2014; 47: 57-63. on human sex hormone-binding globulin and phthalate 39. Wallace DR. Nanotoxicology and metalloestrogens: possible plasticizers. PLoS One 2016; 11: e0151444. involvement in breast cancer. Toxics 2015; 3: 390-413. doi:10.1371/journal. pone.0151444 40. Carreau S, Silandre D, Bois C, Bouraima H, Galeraud-Denis 61. Jakimiuk AJ, Nowicka MA, Zagozda M, Koziol K, I, Delalande C. Estrogens: a new player in spermatogenesis. Lewandowski P, Issat T. High levels of soluble vascular Folia Histochem Cytobiol 2007; 45: S5-S10. endothelial growth factor receptor 1/sFlt1 and low levels of 41. Sharpe RM, McKinnell C, Kivlin C, Fisher JS. Proliferation vascular endothelial growth factor in follicular fluid on the and functional maturation of Sertoli cells, and their day of oocyte retrieval correlate with ovarian relevance to disorders of testis function in adulthood. hyperstimulation syndrom regardless of the stimulation Reproduction 2003; 125: 769-784. protocol. J Physiol Pharmacol 2017; 68: 477-484. 42. Delbes G, Levacher C, Habert R. Estrogen effects on fetal 62. Corradi FP, Corradi RB, Wissner Greene L. Physiology of and neonatal testicular development. Reproduction 2006; the hypothalamic pituitary gonadal axis in the male. Urol 132: 527-538. Clin North Am 2016; 43: 151-162. 43. Ebling FJ, Nwagwu MO, Baines H, Myers M, Kerr JB. The 63. Yeung BH, Wan HT, Law AY, Wong CK. Endocrine hypogonadal (hpg) mouse as a model to investigate the disrupting chemicals: multiple effects on testicular signaling estrogenic regulation of spermatogenesis. Hum Fertil and spermatogenesis. Spermatogenesis 2011; 1: 231-239. (Camb ) 2006; 9: 127-135. 64. Tena-Sempere M. Kisspeptin/GPR54 system as potential 44. Oduwole OO, Peltoketo H, Huhtaniemi IT. Role of follicle- target for endocrine disruption of reproductive development stimulating hormone in spermatogenesis. Front Endocrinol and function. Int J Androl 2010; 33: 360-368. (Lausanne ) 2018; 9: 763. doi: 10.3389/fendo.2018.00763. 65. Delfosse V, Grimaldi M, Cavailles V, Balaguer P, Bourguet 45. Grinspon RP, Loreti N, Braslavsky D, et al . Sertoli cell W. Structural and functional profiling of environmental markers in the diagnosis of paediatric male hypogonadism. ligands for estrogen receptors. Environ Health Perspect J Pediatr Endocrinol Metab 2012; 25: 3-11. 2014; 122: 1306-1313. 46. Wong RL, Walker CL. Molecular pathways: environmental 66. Al-Gubory KH. Environmental pollutants and lifestyle estrogens activate nongenomic signaling to developmentally factors induce oxidative stress and poor prenatal reprogram the epigenome. Clin Cancer Res 2013; 19: 3732- development. Reprod Biomed 2014; 29: 17-31. 3737. 67. Bilinska B, Wiszniewska B, Kosiniak-Kamysz K, et al . 47. Hess RA, Carnes K. The role of estrogen in testis and the Hormonal status of male reproductive system: androgens male reproductive tract: a review and species comparison. and estrogens in the testis and epididymis. In vivo and in Anim Reprod 2004; 1: 5-30. vitro approaches. Reprod Biol 2006; 6: 43-58. 48. Kula K, Walczak-Jedrzejowska R, Slowikowska-Hilczer J, 68. Pawlicki P, Milon A, Zarzycka M, et al . Does signaling of et al . Important functions of estrogens in men breakthrough estrogen-related receptors affect structure and function of 352

bank vole Leydig cells? J Physiol Pharmacol 2017; 68: 87. Klein JP, Mold M, Mery L, Cottier M, Exley C. Aluminum 459-476. content of human semen: Implications for semen quality. 69. Paumgartten FJ. Estrogenic and anti-androgenic endocrine Reprod Toxicol 2014; 50: 43-48. disrupting chemicals and their impact on the male 88. Zhou Q, Xi S. A review on arsenic carcinogenesis: reproductive system. Front Public Health 2015; 3: 165. epidemiology, metabolism, genotoxicity and epigenetic doi:10.3389/fpubh.2015.00165. changes. Regul Toxicol Pharmacol 2018; 99: 78-88. 70. Schlundt A, Buchner S, Janowski R, et al . Structure-function 89. Zubair M, Ahmad M, Qureshi ZI. Review on arsenic- analysis of the DNA-binding domain of a transmembrane induced toxicity in male reproductive system and its transcriptional activator. Sci Rep 2017; 7: 1051. doi: amelioration. Andrologia 2017; 49: e12791. doi: 10.1038/s41598-017-01031-9 10.1111/and.12791 71. Witkiewicz-Kucharczyk A, Bal W. Damage of zinc fingers 90. Arsenic And Arsenic Compounds. https://monographs. in DNA repair proteins, a novel molecular mechanism in iarc.fr/wp-content/uploads/2018/06/mono100C-6.pdf. carcinogenesis. Toxicol Lett 2006; 162: 29-42. 91. Toxic Substances Portal - Arsenic / Toxicological Profile For 72. Byrne C, Divekar SD, Storchan GB, Parodi DA, Martin MB. Arsenic https://www.atsdr.cdc.gov/toxprofiles/tp.asp?id Metals and breast cancer. J Mammary Gland Biol Neoplasia =22&tid=3. 2013; 18: 63-73. 92. Parvez F, Chen Y, Brandt-Rauf PW, et al . Nonmalignant 73. Harris HA, Katzenellenbogen JA, Katzenellenbogen BS. respiratory effects of chronic arsenic exposure from drinking Characterization of the biological roles of the estrogen water among never-smokers in Bangladesh. Environ Health receptors, ERalpha and ERbeta, in estrogen target tissues in Perspect 2008; 116: 190-195. vivo through the use of an ERalpha-selective ligand. 93. Shen S, Li XF, Cullen WR, Weinfeld M, Le XC. Arsenic Endocrinology 2002; 143: 4172-4177. binding to proteins. Chem Rev 2013; 113: 7769-7792. 74. Martin MB, Reiter R, Pham T, et al . Estrogen-like activity of 94. Chen Y, Graziano JH, Parvez F, et al . Arsenic exposure from metals in MCF-7 breast cancer cells. Endocrinology 2003; drinking water and mortality from cardiovascular disease in 144: 2425-2436. Bangladesh: prospective cohort study. BMJ 2011; 342: 75. Kortenkamp A. Are cadmium and other heavy metal d2431. doi: 10.1136/bmj.d2431 compounds acting as endocrine disrupters? Met Ions Life Sci 95. Del Razo LM, Quintanilla-Vega B, Brambila-Colombres E, 2011; 8: 305-317. Calderon-Aranda ES, Manno M, Albores A. Stress proteins 76. Willhite CC, Karyakina NA, Yokel RA, et al . Systematic induced by arsenic. Toxicol Appl Pharmacol 2001; 177: review of potential health risks posed by pharmaceutical, 132-148. occupational and consumer exposures to metallic and 96. Hughes MF. Arsenic toxicity and potential mechanisms of nanoscale aluminum, aluminum oxides, aluminum action. Toxicol Lett 2002; 133: 1-16. doi: hydroxide and its soluble salts. Crit Rev Toxicol 2014; 44 org/10.1016/S0378-4274(02)00084-X (Suppl. 4): 1-80. 97. Ferreira M, Matos RC, Oliveira H, Nunes B, Pereira L. 77. Klotz K, Weistenhofer W, Neff F, Hartwig A, van Thriel C, Impairment of mice spermatogenesis by sodium arsenite. Drexler H. The health effects of aluminum exposure. Dtsch Hum Exp Toxicol 2012; 31: 290-302. Arzteb Int 2017; 114: 653-659. 98. Sarkar M, Chaudhuri GR, Chattopadhyay A, Biswas NM. 78. Buraimoh AA, Ojo SA, Hambolu JO, Adebisi SS. Effect of sodium arsenite on spermato-genesis, plasma Histological study of the effects of aluminum chloride gonadotrophins and testosterone in rats. Asian J Androl exposure on the testis of Wistar rats. Am Int J Contemp Res 2003; 5: 27-31. 2012; 2: 114-122. 99. Sharma G, Kumar M. Arsenic induced histological 79. Kawahara M, Kato-Negishi M. Link between aluminum and alterations in testis of Swiss albino mice and protection by the pathogenesis of Alzheimer’s disease: the integration of the Chlorophytum borivilianum. Asian Pac J Reprod 2014; 3: aluminum and amyloid cascade hypotheses. Int J Alzheimers 282-287. Dis 2011; 2011: 276393. doi: 10.4061/2011/276393 100. Li P, Zhong Y, Jiang X, Wang C, Zuo Z, Sha A. Seminal 80. Linhart C, Talasz H, Morandi EM, et al . Use of underarm plasma metals concentration with respect to semen quality. cosmetic products in relation to risk of breast cancer: a case- Biol Trace Elem Res 2012; 148: 1-6. doi: 10.1007/s12011- control study. EBioMedicin e 2017; 21: 79-85. 012-9335-7 81. Tomczynska M, Saluk J, Sawicka E. Estrogenic impact of 101. Balabanic D, Rupnik M, Klemencic AK. Negative impact cadmium and aluminium [in Polish]. Probl Hig Epidemiol of endocrine-disrupting compounds on human reproductive 2016; 97: 1-5. health. Reprod Fertil Dev 2011; 23: 403-416. 82. Yuan CY, Lee YJ, Hsu GS. Aluminum overload increases 102. Lafuente A, Marquez N, Perez-Lorenzo M, Pazo D, Esquifino oxidative stress in four functional brain areas of neonatal rats. AI. Cadmium effects on hypothalamic-pituitary-testicular J Biomed Sci 2012; 19: 51. doi: 10.1186/1423-0127-19-51 axis in male rats. Exp Biol Med 2001; 226: 605-611. 83. Martinez CS, Escobar CG, Uranga-Ocio JA, et al . 103. Siu ER, Mruk DD, Porto CS, Cheng CY. Cadmium-induced Aluminum exposure for 60 days at human dietary levels testicular injury. Toxicol Appl Pharmacol 2009; 238: 240-249. impairs spermatogenesis and sperm quality in rats. Reprod 104. De Franciscis P, Ianniello R, Labriola D, et al . Toxicol 2017; 73: 128-141. Environmental pollution due to cadmium: measure of 84. Mouro VG, Menezes TP, Lima GDA, et al . How bad is semen quality as a marker of exposure and correlation with aluminum exposure to reproductive parameters in rats? Biol reproductive potential. Clin Exp Obstet Gynecol 2015; 42: Trace Elem Res 2018; 183: 314-324. 767-770. 85. Yousef MI, Kamel KI, El-Guendi MI, El-Demerdash FM. 105. Kumar S, Sharma A. Cadmium toxicity: effects on human An in vitro study on reproductive toxicity of aluminium reproduction and fertility. Rev Environ Health 2019; pii: chloride on rabbit sperm: the protective role of some /j/reveh.ahead-of-print/reveh-2019-0016/reveh-2019- antioxidants. Toxicology 2007; 239: 213-223. 0016.xml. doi: 10.1515/reveh-2019-0016 86. Zatta P, Lain E, Cagnolini C. Effects of aluminum on activity 106. Byrne C, Divekar SD, Storchan GB, Parodi DA, Martin of Krebs cycle enzymes and glutamate dehydrogenase in rat MB. Cadmium - a metallohormone? Toxicol Appl brain homogenate. Eur J Biochem 2000; 267: 3049-3055. Pharmacol 2009; 238: 266-271. 353

107. Ren XY, Zhou Y, Zhang JP, Feng WH, Jiao BH. Expression from different occupational settings around the globe: a of metallothionein gene at different time in testicular review. Environ Sci Pollut Res Int 2016; 23: 20151-20167. interstitial cells and liver of rats treated with cadmium. 126. Horky P, Jancikova P, Zeman L. The effect of a supplement World J Gastroenterol 2003; 9: 1554-1558. of chromium (picolinate) on the level of blood glucose, 108. Valko M, Morris H, Cronin MT. Metals, toxicity and insulin activity and changes in laboratory evaluation of the oxidative stress. Curr Med Chem 2005; 12: 1161-1208. ejaculate of breeding boars. Acta Universitatis Agriculturae 109. Acharya UR, Mishra M, Patro J, Panda MK. Effect of et Silviculturae Mendelianae Bruneacta 2012; 60: 49-56. vitamins C and E on spermatogenesis in mice exposed to 127. Bassey IE, Essien OE, Isong IKP, Udoh AE, Agbara GS. cadmium. Reprod Toxicol 2008; 25: 84-88. Seminal plasma chromium, cadmium and lead levels in 110. Pandya C, Pillai P, Nampoothiri LP, Bhatt N, Gupta S, infertile men. J Med Sci 2013; 13: 497-500. Gupta S. Effect of lead and cadmium co-exposure on 128. Acharya UR, Mishra M, Tripathy RR, Mishra I. Testicular testicular steroid metabolism and antioxidant system of dysfunction and antioxidative defense system of Swiss adult male rats. Andrologia 2012; 44: 813-822. mice after chromic acid exposure. Reprod Toxicol 2006; 22: 111. Jahan S, Khan M, Ahmed S, Ullah H. Comparative analysis 87-91. of antioxidants against cadmium induced reproductive 129. Subramanian S, Rajendiran G, Sekhar P, Gowri C, toxicity in adult male rats. Syst Biol Reprod Med 2014; 60: Govindarajulu P, Aruldhas MM. Reproductive toxicity of 28-34. chromium in adult bonnet monkeys (Macaca radiata 112. Pillai P, Pandya C, Bhatt N, Gupta SS. Biochemical and Geoffrey). Reversible oxidative stress in the semen. Toxicol reproductive effects of gestational/lactational exposure to Appl Pharmacol 2006; 215: 237-249. lead and cadmium with respect to testicular 130. Geoffroy-Siraudin C, Perrard MH, Chaspoul F, et al . steroidogenesis, antioxidant system, endogenous sex Validation of a rat seminiferous tubule culture model as a steroid and cauda-epididymal functions. Andrologia 2012; suitable system for studying toxicant impact on meiosis 44: 92-101. effect of hexavalent chromium. Toxicol Sci 2010; 116: 113. Zhang M, He Z, Wen L, et al . Cadmium suppresses the 286-296. proliferation of piglet Sertoli cells and causes their DNA 131. Pereira ML, das Neves RP, Oliveira H, Santos TM, de Jesus damage, cell apoptosis and aberrant ultrastructure. JP. Effect of Cr(V) on reproductive organ morphology and Reprod Biol Endocrinol 2010; 8: 97. doi: 10.1186/1477- sperm parameters: an experimental study in mice. Environ 7827-8-97 Health 2005; 4: 9. doi: 10.1186/1476-069X-4-9 114. Adamkovicova M, Toman R, Martiniakova M, et al . Sperm 132. Wang Z, Chen Z, Zuo Q, et al . Reproductive toxicity in motility and morphology changes in rats exposed to adult male rats following intra-articular injection of cobalt- cadmium and diazinon. Reprod Biol Endocrinol 2016; 14: chromium nanoparticles. J Orthop Sci 2013; 18: 1020- 42. doi: 10.1186/s12958-016-0177-6 1026. 115. Wang YX, Sun Y, Feng W, et al . Association of urinary 133. Chen SY, Chang CH, Hu CC, Chen CC, Chang YH, Hsieh metal levels with human semen quality: A cross-sectional PH. Metal ion concentrations and semen quality in patients study in China. Environ Int 2016; 91: 51-59. undergoing hip arthroplasty: a prospective comparison 116. Famurewa AC, Ugwuja EI. Association of blood and between metal-on-metal and metal-on-polyethylene seminal plasma cadmium and lead levels with semen implants. J Orthop Res 2016; 34: 544-551. quality in non-occupationally exposed infertile men in 134. Hokin B, Adams M, Ashton J, Louie H. Comparison of the Abakaliki, South East Nigeria. J Family Reprod Health dietary cobalt intake in three different Australian diets. Asia 2017; 11: 97-103. Pac J Clin Nutr 2004; 13: 289-291. 117. Davar R, Sekhavat L, Naserzadeh N. Semen parameters of 135. Leyssens L, Vinck B, Van Der Straeten C, Wuyts F, Maes non-infertile smoker andnon-smoker men. J Med Life 2012; L. Cobalt toxicity in humans - a review of the potential 5: 465-468. sources and systemic health effects. Toxicology 2017; 387: 118. Ranganathan P, Rao KA, Sudan JJ, Balasundaram S. 43-56. Cadmium effects on sperm morphology and semenogelin 136. Madzharova M, Gluhcheva Y, Pavlova E, Atanassova N. with relates to increased ROS in infertile smokers: an in Effect of cobalt on male reproductive organs during vitro and in silico approach. Reprod Biol 2018; 18: 189-197. puberty. Biotechnol Biotechnol Equip 2010; 24: 321-324. 119. Huang X, Zhang B, Wu L, et al . Association of exposure to 137. Ahmed E, Al-Thani AS, Al-Thani K, Drmani H, Owais W. ambient fine particulate matter constituents with semen Effects of chronic exposure to cobalt chloride on the quality among men attending a fertility center in China. fertility and testes in mice. J Appl Biol Sci 2008; 2: 1-6. Environ Sci Technol 2019; 53: 5957-5965. 138. Zeng Q, Zhou B, Feng W, et al . Associations of urinary 120. Chromium, Nickel and Welding. Monographs on the metal concentrations and circulating testosterone in Evaluation of Carcinogenic Risks to Humans. International Chinese men. Reprod Toxicol 2013; 41: 109-114. Agency for Research on Cancer (Lyon), 1990, pp. 49. 139. Tsunoda S, Kawano N, Miyado K, Kimura N, Fujii J. 121. Sawicka E, Dlugosz A. The role of 17 b-estradiol Impaired fertilizing ability of superoxide dismutase 1- metabolites in chromium-induced oxidative stress. Adv deficient mouse sperm during in vitro fertilization. Biol Clin Exp Med 2017; 26: 215-221. Reprod 2012; 87: 121. doi: 10.1095/biolreprod.112.102129 122. Sugden K, Stearns D. The role of chromium(V) in the 140. Ogorek M, Gasior L, Pierzchala O, Daszkiewicz R, mechanism of chromate-induced oxidative DNA damage and Lenartowicz M. Role of copper in the process of cancer. J Environ Pathol Toxicol Oncol 2000; 19: 215-230. spermatogenesis. Postepy Hig Med Dosw 2017; 71: 123. Anderson RA. Chromium as an essential nutrient for humans. 663-683. Regul Toxicol Pharmacol 1997; 26 (1 pt 2): S35-S41. 141. Tvrda E, Peer R, Sikka SC, Agarwal A. Iron and copper in 124. Sawicka E, Piwowar A, Musiala T, Dlugosz A. The male reproduction: a double-edged sword. J Assist Reprod estrogens/chromium interaction in the nitric oxide Genet 2015; 32: 3-16. generation. Acta Pol Pharm 2017; 74: 785-791. 142. Mendel RR. Metabolism of molybdenum. In: Metallomics 125. Junaid M, Hashmi MZ, Malik RN, Pei DS. Toxicity and and the Cell. Series: Metal Ions in Life Sciences. L Banci oxidative stress induced by chromium in workers exposed (ed). Dordrecht, Springer, 2013, pp. 503-528. 354

143. Wooton-Kee CR, Jain AK, Wagner M, et al . Elevated 161. Bersenyi A, Berta E, Kadar I, Glavits R, Szilagyi M, Fekete copper impairs hepatic nuclear receptor function in SG. Effects of high dietary molybdenum in rabbits. Acta Wilson’s disease. J Clin Invest 2015; 125: 3449-3460. Vet Hung 2008; 56: 41-55. 144. Kim K, Melough MM, Vance TM, et al . The relationship 162. Murray FJ, Sullivan FM, Hubbard SA, Hoberman AM, between zinc intake and cadmium burden is influenced by Carey S. A two-generation reproductive toxicity study of smoking status. Food Chem Toxicol 2019; 125: 210-216. sodium molybdate dihydrate administered in drinking 145. Li Y, Gao Q, Li M, Li M, Gao X. Cadmium, chromium, water or diet to Sprague-Dawley rats. Reprod Toxicol 2019; and copper concentration plus semen-quality in 84: 75-92. environmental pollution site, China. Iran J Public Health 163. Zeng Q, Feng W, Zhou B, et al . Urinary metal 2014; 43: 35-41. concentrations in relation to semen quality: a cross- 146. Abdul-Rasheed OF. Association between seminal plasma sectional study in China. Environ Sci Technol 2015; 49: copper and magnesium levels with oxidative stress in Iraqi 5052-5059. infertile men. Oman Med J 2010; 25: 168-172. 164. Meeker JD, Rossano MG, Protas B, et al . Cadmium, lead, 147. Palani K, Jabbar AA, Jagannathan N, Muthiah SS, and other metals in relation to semen quality: human Narendiran NJ. Male infertility with poor semen quality evidence for molybdenum as a male reproductive toxicant. and correlation with trace metal concentration in and Environ Health Perspect 2008; 116: 1473-1479. around Chennai, India. Int J Sci Res 2018; 7: 338-347. 165. Ema M, Kobayashi N, Naya M, Hanai S, Nakanishi J. 148. Ravibabu K, Barman T, Rajmohan HR. Serum neuron- Reproductive and developmental toxicity studies of specific enolase, biogenic amino-acids and manufactured nanomaterials. Reprod Toxicol 2010; 30: neurobehavioral function in lead-exposed workers from 343-352. lead-acid battery manufacturing process. Int J Occup 166. Braydich-Stolle L, Hussain S, Schlager JJ, Hofmann MC. Environ Med 2015; 6: 50-57. In vitro cytotoxicity of nanoparticles in mammalian 149. Benoff S, Jacob A, Hurley IR. Male infertility and germline stem cells. Toxicol Sci 2005; 88: 412-419. environmental exposure to lead and cadmium. Hum Reprod 167. Elsamanoudy A, Shaalan D, Gaballah M, Abo el-Atta H, Update 2000; 6: 107-121. Helaly A. Possible effects of metallosis on spermatozoal 150. He Y, Zou Q, Chen H, Weng S, Luo T, Zeng X. Lead apoptotic genes expression in individuals with inhibits human sperm functions by reducing the levels of intramedullary nailing prosthesis. Biol Trace Elem Res intracellular calcium, cAMP, and tyrosine phosphorylation. 2014; 158: 334-341. Tohoku J Exp Med 2016; 238: 295-303. 168. Lauwerys R, Roels H, Genet P, Toussaint G, Bouckaert A, 151. Jegede AI, Offor U, Azu OO, Akinloye O. Red palm oil De Cooman S. Fertility of male workers exposed to attenuates lead acetate induced testicular damage in adult mercury vapor or to manganese dust: a questionnaire study. male Sprague-Dawley rats. Evid Based Complemen Am J Ind Med 1985; 7: 171-176. Alternat Med 2015; 2015: 13026. doi: 169. Keck C, Bergmann M, Ernst E, Muller C, Kliesch S, 10.1155/2015/130261 Nieschlag E. Autometallographic detection of mercury in 152. Al-Juboori BM, Hamdan FB, Al-Salihi AR. Effect of low- testicular tissue of an infertile man exposed to mercury dose lead on semen quality and sperm’s DNA integrity in vapor. Reprod Toxicol 1993; 7: 469-475. adult male mice. Cent Eur J Exp Biol 2013; 2: 4-14. 170. Choy CM, Lam CW, Cheung LT, Briton-Jones CM, 153. Hsiao W, Schlegel PN. Assessment of the male partner. In: Cheung LP, Haines CJ. Infertility, blood mercury The Subfertility Handbook, A Clinician’s Guide. G. Kovacs concentrations and dietary seafood consumption: a case- (ed). Cambridge University Press, 2011, pp. 43-57. control study. BJOG 2002; 109: 1121-1125. 154. Spano M, Bonde JP, Hjollund HI, Kolstad HA, Cordelli E, 171. Heath JC, Abdelmageed Y, Braden TD, Goyal HO. The Leter G. Sperm chromatin damage impairs human fertility. effects of chronic ingestion of mercuric chloride on The Danish First Pregnancy Planner Study Team. Fertil fertility and testosterone levels in male Sprague Dawley Steril 2000; 73: 43-50. rats. J Biomed Biotechnol 2012; 2012: 815186. 155. Li N, Xu P, Jing WX, Hwang JS, Wang L. Toxic effects of doi:10.1155/2012/815186 Pb 2+ entering sperm through Ca 2+ channels in the 172. Mocevic E, Specht IO, Marott JL, et al . Environmental freshwater crab Sinopotamon henanense. Aquat Toxicol mercury exposure, semen quality and reproductive 2017; 192: 24-29. hormones in Greenlandic Inuit and European men: a cross- 156. Taha EA, Sayed SK, Ghandour NM, et al . Correlation sectional study. Asian J Androl 2013; 15: 97-104. between seminal lead and cadmium and seminal parameters 173. Kong L, Tang M, Zhang T, et al . Nickel nanoparticles in idiopathic oligoasthenozoospermic males. Cent exposure and reproductive toxicity in healthy adult rats. Int European J Urol 2013; 66: 84-92. J Mol Sci 2014; 15: 21253-21269. 157. Pant N, Kumar G, Upadhyay A, Gupta YK, Chaturvedi PK. 174. Hu W, Yu Z, Gao X, Wu Y, Tang M, Kong L. Study on the Correlation between lead and cadmium concentration and damage of sperm induced by nickel nanoparticle exposure. semen quality. Andrologia 2014; 47: 887-891. Environ Geochem Health 2019; Jul 5. doi: 10.1007/s10653- 158. Turnlund JR, Friberg LT. Molybdenum. In: Handbook on 019-00364-w the Toxicology of Metals. GF Nordberg, BA Fowler, M 175. Guzikowski W, Szynkowska MI, Motak-Pochrzest H, Nordberg, LT Friberg (eds). London UK, Elsevier, 2007, Pawlaczyk A, Sypniewski S. Trace elements in seminal pp. 731-741. plasma of men from infertile couples. Arch Med Sci 2015; 159. Bi CM, Zhang YL, Liu FJ, Zhou TZ, Yang ZJ, Gao SY. The 11: 591-598. effect of molybdenum on the in vitro development of 176. Danadevi K, Rozati R, Reddy PP, Grover P. Semen quality mouse preimplantation embryos. Sys Biol Reprod Med of Indian welders occupationally exposed to nickel and 2013; 59: 69-73. chromium. Reprod Toxicol 2003; 17: 451-456. 160. Murray FJ, Tyl RW, Sullivan FM, Tiwary AK, Carey S. 177. Zafar A, Eqani SA, Bostan N, et al . Toxic metals signature Developmental toxicity study of sodium molybdate in the human seminal plasma of Pakistani population and dihydrate administered in the diet to Sprague Dawley rats. their potential role in male infertility. Environ Geochem Reprod Toxicol 2014; 49: 202-208. Healt h 2015; 37: 515-527. 355

178. Zhou Y, Fu XM, He DL, et al . Evaluation of urinary metal 189. Vijaya Bharathi A, Jaya Prakash G, Krishna KM, et al . concentrations and sperm DNA damage in infertile men Protective effect of alpha glucosyl hesperidin (G- from an infertility clinic. Environ Toxicol Pharmacol 2016; hesperidin) on chronic vanadium induced testicular toxicity 45: 68-73. and sperm nuclear DNA damage in male Sprague Dawley 179. Marzec-Wroblewska U, Kaminski P, Lakota P, et al . The rats. Andrologia 2015; 47: 568-578. employment of IVF techniques for establishment of 190. Fortoul TI, Bizarro-Nevares P, Acevedo-Nava S, et al . sodium, copper and selenium impact upon human sperm Ultrastructural findings in murine seminiferous tubules as a quality. Reprod Fertil Dev 2015; Mar 19. doi: consequence of subchronic vanadium pentoxide inhalation. 10.1071/RD15041. Reprod Toxicol 2007; 23: 588-592. 180. Domoslawska A, Zdunczyk S, Franczyk M, Kankofer M, 191. Wang YX, Chen HG, Li XD, et al . Concentrations of Janowski T. Selenium and vitamin E supplementation vanadium in urine and seminal plasma in relation to semen enhances the antioxidant status of spermatozoa and quality parameters, spermatozoa DNA damage and serum improves semen quality in male dogs with lowered fertility. hormone levels. Sci Total Environ 2018; 645: 441-448. Andrologia 2018; 50: e13023. doi: 10.1111/and.13023 192. Chandra AK, Ghosh R, Chatterjee A, Sarkar M. Effects of 181. El-Sharawy M, Eid E, Darwish S, et al . Effect of organic vanadate on male rat reproductive tract histology, oxidative and inorganic selenium supplementation on semen quality stress markers and androgenic enzyme activities. J Inorg and blood enzymes in buffalo bulls. Anim Sci J 2017; 88: Biochem 2007; 101: 944-956. 999-1005. 193. Giaccio L, Cicchella D, De Vivo B, Lombardi G, De Rosa 182. Taghizadeh L, Eidi A, Mortazavi P, Rohani AH. Effect of M. Does heavy metals pollution affects semen quality in selenium on testicular damage induced by varicocele in men? A case of study in the metropolitan area of Naples adult male Wistar rats. J Trace Elem Med Biol 2017; 44: (Italy). J Geochem Explor 2012; 112: 218-225. 177-185. 194. Sukhn CM, Awwad JT, Ghantous A, Zaatari GS. 183. Wan ZZ, Chen HG, Lu WQ, Wang YX, Pan A. Associations of semen quality with non-essential heavy Metal/metalloid levels in urine and seminal plasma in metals in blood and seminal fluid: data from the relation to computer-aided sperm analysis motion Environment and Male Infertility (EMI) study in Lebanon. parameters. Chemosphere 2019; 214: 791-800. J Assist Reprod Genet 2018; 35: 1691-1701. 184. Saaranen M, Suistomaa U, Kantola M, Remes E, Vanha- 195. Ghaffari MA, Motlagh B. In vitro effect of lead, silver, tin, Perttula T. Selenium in reproductive organs, seminal fluid mercury, indium and bismuth on human sperm creatine and serum of men and bulls. Hum Reprod 1986; 1: 61-64. kinase activity: a presumable mechanism for men 185. Hawkes WC, Alkan Z, Wong K. Selenium supplementation infertility. Iran Biomed J 2011; 15: 38-43. does not affect testicular selenium status or semen quality 196. Wang YX, Sun Y, Huang Z, et al . Associations of urinary in North American men. J Androl 2009; 30: 525-533. metal levels with serum hormones, spermatozoa apoptosis 186. Eroglu M, Sahin S, Durukan B, et al . Blood serum and and sperm DNA damage in a Chinese population. Environ seminal plasma selenium, total antioxidant capacity and Int 2016; 94: 177-188. coenzyme q10 levels in relation to semen parameters in men with idiopathic infertility. Biol Trace Elem Res 2014; Received: May 10, 2019 159: 46-51. Accepted: June 28, 2019 187. Safarinejad MR, Safarinejad S. Efficacy of selenium and/or N-acetyl-cysteine for improving semen parameters in Author’s address: Assoc. Prof. Ewa Maria Kratz, infertile men: a double- blind, placebo controlled, Department of Laboratory Diagnostics, Faculty of Pharmacy randomized study. J Urol 2009; 181: 741-751. with Division of Laboratory Diagnostics, Wroclaw Medical 188. Wilk A, Szypulska-Koziarska D, Wiszniewska B. The University, 211A Borowska Street, 50-556 Wroclaw, Poland. toxicity of vanadium on gastrointestinal, urinary and E-mail: [email protected] reproductive system, and its influence on fertility and fetuses malformations. Postepy Hig Med Dosw 2017; 71: 850-859.