SUPPLEMENT ARTICLE Environmental Factors and Timing: Expert Panel Research Needs

Germaine M. Buck Louis, PhDa, L. Earl Gray, Jr, PhDb, Michele Marcus, PhD, MPHc, Sergio R. Ojeda, DVMd, Ora H. Pescovitz, MDe, Selma Feldman Witchel, MDf, Wolfgang Sippell, MD, PhDg, David H. Abbott, PhDh, Ana Soto, MDi, Rochelle W. Tyl, PhDj, Jean-Pierre Bourguignon, MD, PhDk, Niels E. Skakkebaek, MD, DMScl, Shanna H. Swan, PhDm, Mari S. Golub, PhDn, Martin Wabitsch, MD, PhDo, Jorma Toppari, MD, PhDp, Susan Y. Euling, PhDq aEpidemiology Branch, National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland; bEndocrinology Branch, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina; cDepartment of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia; dDivision of Neuroscience, Oregon National Research Center-Oregon Health and Sciences University, Beaverton, Oregon; eDepartment of Pediatrics and Cellular and Integrative Physiology, Riley Hospital for Children, Indiana University School of , Indianapolis, Indiana; fDivision of , Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania; gDivision of Endocrinology, Department of Pediatrics, University of Kiel, Kiel, Germany; hDepartment of Obstetrics/Gynecology and Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin; iDepartment of Anatomy and Cell Biology, Tufts University School of Medicine, Boston, Massachusetts; jCenter for Life Sciences and Toxicology, RTI International, Research Triangle Park, North Carolina; kCHU Sart-Tilman, University of Liege, Belgium; lUniversity Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark; mDepartment of Family & Community Medicine, University of Missouri, Columbia, Missouri; nOffice of Environmental Health Hazard Assessment, California Environmental Protection Agency, Sacramento, California; oDepartment of Pediatric and Adolescent Medicine, University of Ulm, Ulm, Germany; pDepartments of Physiology and Pediatrics, University of Turku, Turku, Finland; qNational Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Washington, DC

The authors have indicated they have no financial relationships relevant to this article to disclose.

ABSTRACT Serono Symposia International convened an expert panel to review the impact of environmental influences on the regulation of pubertal onset and progression while identifying critical data gaps and future research priorities. An expert panel reviewed www.pediatrics.org/cgi/doi/10.1542/ the literature on endocrine-disrupting chemicals, body size, and puberty. The panel peds.2007-1813E concluded that available experimental animal and human data support a possible doi:10.1542/peds.1813E role of endocrine-disrupting chemicals and body size in relation to alterations in The views expressed in this article are those of the authors and do not necessarily pubertal onset and progression in boys and girls. Critical data gaps prioritized for reflect the views or policies of the US future research initiatives include (1) etiologic research that focus on environmen- Environmental Protection Agency. Mention tally relevant levels of endocrine-disrupting chemicals and body size in relation to of trade names of commercial products normal puberty as well as its variants, (2) exposure assessment of relevant endo- does not constitute endorsement or recommendation for use. crine-disrupting chemicals during critical windows of human development, and (3) Drs Buck Louis, Gray, and Marcus basic research to identify the primary signal(s) for the onset of - contributed equally to this work. releasing –dependent/central puberty and gonadotropin-releasing hor- Key Words mone–independent/peripheral puberty. Prospective studies of couples who are plan- human puberty, puberty timing, ning or pregnant women are needed to capture the continuum of development, , development, genital development, exposures at critical windows while assessing a spectrum of pubertal markers as endocrine disruptors, body fat outcomes. Coupled with comparative species studies, such research may provide Accepted for publication Sep 5, 2007 insight regarding the causal ordering of events that underlie pubertal onset and Address correspondence to Germaine M. Buck progression and their role in the pathway of adult-onset disease. Louis, PhD, Epidemiology Branch, Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, 6100 Executive Blvd, Room 7B03, Rockville, MD 20852. E-mail: N LIGHT OF an increasing body of evidence supporting environmental influences on [email protected] Ipubertal onset and progression in contemporary birth cohorts, an expert panel met PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275). Copyright © 2008 by the during and after the Serono Symposia International’s “The Role of Environmental American Academy of Pediatrics Factors on the Onset and Progression of Puberty” to identify research priorities for delineating the impact of environmental influences on children’s pubertal experi- ences. An expert review of available animal, clinical, and epidemiologic data was undertaken and synthesized for identifying critical data gaps that are relevant for prioritizing a multidisciplinary research agenda. For purposes of this article, the environment is defined as the sum of all external conditions that affect life, development, and survival of an organism (www.epa.gov/ocepaterms/eterms.html). By extension, an environmental factor is defined as a non-

S192 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 FIGURE 1 Regulation of human puberty onset and progression via the HPG and the HPA axes. The key regulatory changes that occur for the initiation and progression of puberty in boys and girls are shown. The HPG activation requires sig- naling from the central nervous system (CNS) to the hy- pothalamus. The releases GnRH, which in turn stimulates the production of LH and FSH from the pituitary. LH and FSH activate the to produce sex , which in turn initiates pubertal changes in many of the target organs. The HPA activation requires signaling from the CNS to the hypothalamus. The hypo- thalamus releases adrenocorticotropin releasing hor- mone (CRH) that in turn stimulates the production of ad- renocortical tropic hormone (ACTH) from the pituitary. ACTH activates the to produce andro- stenedione and (DHEA) that in turn initiates armpit hair, pubic hair, and skin changes. action is also considered to be part of the initi- ation of armpit and pubic hair development. Positive (ϩ) and negative (Ϫ) indicate stimulatory and inhibitory sig- nals and “ϩ/Ϫ” in the CNS indicates a combination of excitatory and inhibitory neuronal signals.

genetic factor; however, for purposes of brevity and during childhood. Puberty is marked by the reactivation consistent with the weight of evidence regarding envi- of the HPG axis manifested by an increase in frequency ronmental influences on puberty, this review focuses on and amplitude of gonadotropin releasing hormone endocrine-disrupting chemicals (EDCs) and body size in (GnRH) pulses in the hypothalamus, leading to a rise in relation to puberty timing. An in-depth discussion of the pulsatile secretion of the LH and FSH literature cited in this article is beyond the scope of this from the anterior pituitary. Gonadotropin release stim- article, but key study aspects are summarized in accom- ulates the . In girls, such maturation of reproduc- panying tables. tive neuroendocrine function eventually leads to the onset of ovulatory menstrual cycles. Appropriate gonad- REGULATION OF NORMAL PUBERTY ONSET AND otropin regulation of ovarian function results in ovarian PROGRESSION IN AND ANIMALS follicle secretion of ovarian from theca cells Puberty is the period of transition from childhood to and from granulosa cells before and and is marked by the development of sec- secretion of from the corpus luteum and ondary , accelerated growth, be- estradiol after ovulation. In boys, LH initiates the secre- havioral changes, and eventual attainment of reproduc- tion of androgens ( and ) tive capacity. Available approaches for the assessment of from the testicular Leydig cells. Such onset of gonadal pubertal onset and progression have recently been re- endocrine function is termed . The initial viewed,1 including the use of Tanner stages2,3 for female molecular triggers of puberty onset remain unknown, breast and pubic hair development and male gonadal although genetic and environmental factors are sus- and pubic hair development. Menarche is also an impor- pected. tant marker used for assessing puberty in girls. Biochemical Puberty is also associated with an independent phys- markers for female puberty onset and progression include iologic event, , or adrenal activation, that assaying elevations in reproductive hormones (eg, lutein- typically occurs between 6 and 8 years of age in both izing hormone [LH], follicle-stimulating hormone [FSH], genders. Adrenarche leads to , the secondary 17␤-estradiol, inhibin A and B) before the onset of physical sexual changes including pubic hair development, , signs (eg, Tanner stage 2). Other mat- and . Adrenarche is marked by increased 17␣- urational markers, such as determinations (radio- hydroxylase (17,20 lyase) activity of the P450c17 en- graph of left wrist) and ultrasonographic assessment of zyme and increased cytochrome b activity resulting in ovarian and uterine volume, can be used. increased dehydroepiandrosterone, dehydroepiandros- Puberty changes occur as a consequence of the acti- terone sulfate, and androstenedione production. These vation of the hypothalamic-pituitary-gonadal (HPG) axis initial hormonal increases rise over time, resulting in a and hypothalamic-pituitary-adrenal (HPA) axis. The cumulative dosage of androgens. Adrenarche is a strictly HPG axis is under the control of both inhibitory and primate phenomenon.4 Although little information is stimulatory mechanisms, as illustrated in Fig 1. In the available, there is some evidence that adrenarche occurs human, the HPG is active in the midfetal, neonatal, and before puberty in chimpanzees and during the neonatal early infancy periods but becomes relatively quiescent period in rhesus macaques and baboons.5

PEDIATRICS Volume 121, Supplement 3, February 2008 S193 Downloaded from www.aappublications.org/news by guest on September 29, 2021 Recently, much has been learned about the central been identified, gene(s) upstream that provide the initial mechanisms underlying the initiation of mammalian pu- trigger of puberty timing remain largely unknown. The berty. Rodents, nonhuman , and humans have integrated use of genomics and proteomics using trans- been and remain the main species used to study the basic genic rodent models, nonhuman primates, and humans components and regulatory hierarchies that control the with alterations in the onset of puberty is beginning to process of puberty. Traditionally assessed pubertal onset uncover some of the common evolutionary conserved end points in rodents include the age of male preputial molecular components that are used by the neuroendo- separation (PPS), an androgen-mediated event, and, in crine brain to control GnRH secretion and, in turn, the females, the age of female vaginal opening (VO), an initiation of puberty in both rodents and higher pri- -mediated event. Age at first estrus is an end mates.20–23 An example is the homeodomain gene TTF1, point used to assess completion of the pubertal process in a transcription factor that was recently shown to be females because it occurs the day after the first preovu- involved in the neuroendocrine control of both primate latory surge of gonadotropins.6 Some studies have as- and rodent puberty.24 In addition, recent findings sug- sessed the age of breast cell differentiation events in the gest that structural remodeling of GnRH neurons may mouse and rat.7,8 Estrogen-mediated pubertal events play a key role in the onset of puberty.25 that occur in nonhuman female primates include men- Although the initiating trigger(s) for pubertal onset is arche, sex skin swelling and reddening, and nipple unknown for rodents, nonhuman primates and humans, growth.9,10 Epiphyseal closure and cessation of long bone earlier molecular markers have been identified, such as growth also have been assessed.11 In male monkeys, the newly described -GPR54 regulatory sys- increases in testicular volume indicate onset of male tem. Humans who carry mutations of the GPR54 recep- puberty and reflect both gonadotropin- and testoster- tor22,23 and mice that lack this receptor23,26 each fail to one-mediated events.12 Measurement of changes in tes- reach puberty, indicative that activation of this signaling ticular size seems to be a reliable, noninvasive procedure complex is essential for pubertal onset. Peptides that are to detect the initiation of puberty in both human and produced by peripheral tissues, such as and insu- nonhuman primates.13 lin-like growth factor 1, seem to be more important in In addition to differences in the time frame, progres- maintaining pubertal progression rather than in its ini- sion, and phenotypic landmarks of puberty,14 there is a tiation despite that -like growth factor 1 has been fundamental difference in the neuroendocrine process reported to accelerate pubertal initiation in rodents and that controls the initiation of puberty in rodents versus monkeys (reviewed by Ojeda and Terasawa18). primates. In rodents and sheep,15 GnRH secretion is Understanding the mechanisms underlying the initi- maintained at low levels during juvenile development ation, progression, and regulation of normal human pu- by strong inhibitory control, whereas a similar berty is essential for assessing the effect(s) of EDCs on reduction in GnRH secretion is achieved in primates human development. With limited empirical popula- (including humans) by central mechanisms that operate tion-based data, it is important to consider other sources independent of gonadal regulatory inputs.16,17 Thus, data of data, such as those that arise from clinical populations. indicate that the peripubertal regulation of the GnRH- Although external validity may be limited from these releasing system is a more centrally controlled process in data sources, useful information about potential cause is primates than in rodents that exhibit “gonadal” control possible. of GnRH secretion. Despite this operational difference, the pubertal activation of GnRH release in rodents and CLUES FROM CLINICAL RESEARCH THAT SUPPORT primates is initiated and regulated by similar excitatory ENVIRONMENTAL INFLUENCES and inhibitory pathways, providing input to GnRH neu- A number of clinical conditions offer clues regarding the rons (reviewed by Ojeda and Terasawa18 and Ojeda and influence on environmental factors, such as nutrition Skinner6). These inputs include both trans-synaptic and and body size, on puberty. In fact, a recent clinical report glia-to-neuron communication pathways. As neuronal attributed topical application of lavender and tea tree oils networks that use excitatory amino acids and the newly to in prepubescent boys on the basis of in discovered kisspeptin peptide for neurotransmission or vitro evidence supporting their weak estrogenic and neuromodulation become activated, there is a concom- anti-androgenic activities.27 A brief overview of environ- itant reduction in the activity of those neurons using the mental influences follows in relation to precocious pu- inhibitory neurotransmitters ␥ amino butyric acid and berty, , and polycystic syndrome opioid peptides for transsynaptic communication. In ad- (PCOS). dition to this neuron-to-neuron flow of information, several trophic molecules have been identified as com- ponents of the cell–cell signaling process used by glial cells to regulate GnRH secretion. Prominent among Precocious and delayed puberty in humans can have a these regulatory systems is a signaling complex that uses genetic and/or environmental cause. Precocious puberty epidermal growth factor–like ligands and members of is defined herein as the development of secondary sex- the epidermal growth factor family for glia-to- ual characteristics before 8 years of age in girls and boys. neuron communication (reviewed by Ojeda et al19). Al- Precocious puberty can be classified into “central,” or go- though some gene products that are involved in glia and nadotropin-dependent, precocious puberty; “peripheral,” neuronal communication to regulate puberty onset have or gonadotropin-independent, precocious puberty; or

S194 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 combined. Examples of genetic forms of peripheral pre- the National Institutes of Health definition to include 2 cocious puberty are McCune Albright syndrome in girls of 3 of the following: (1) clinical or biochemical evidence and testotoxicosis (or familial male precocious puberty) of ; (2) intermittent or absent men- in boys. strual cycles; and (3) polycystic ovary morphology as Premature and premature adrenarche may visualized by ultrasound. be regarded as partial forms of precocious puberty, in Puberty timing is altered in some girls with PCOS, which the full spectrum of pubertal changes is absent dependent, in part, on androgen secretion/exposure and and only specific changes occur.28 is nutritional status. Premature pubarche has been re- usually slowly progressing or even self-limiting but can ported among some but not all girls with PCOS and is occasionally transform into overt central precocious pu- believed to arise from increased adrenal androgen secre- berty. Although not precocious puberty, per se, prema- tion secondary to premature adrenal pubertal matura- ture breast development and gynecomastia after expo- tion in the absence of other known causes (eg, CAH, sure to estrogen-containing products have been reported androgen-secreting tumors, Cushing syndrome). Andro- in girls and boys, respectively, with reversal on cessation gen concentrations are elevated for chronologic age but of the exposure.29–33 appropriate for the stage of pubic hair development. Skeletal maturation may be normal or slightly advanced. The presence of insulin resistance/hyperinsulinemia, Pubertal Delay dyslipidemia, exaggerated GnRH-stimulated ovarian Delayed puberty, defined as the absence of breast devel- thecal cell androgen secretion in the early stages of pu- opment by 13 years of age in girls or testicular volume berty, and subsequent development of hyperandrogenic Ͻ4 mL by 14 years of age in boys, can occur as a result chronic during the later stages of puberty of primary hypothalamic-pituitary dysfunction or pri- suggest that premature pubarche is related to the devel- mary gonadal failure. The most common cause of pu- opment of PCOS.36 In addition, the age at menarche is bertal delay is constitutional, representing a transient typically ϳ6 months earlier in girls with PCOS than in delay in sexual development that is a variant of normal. unaffected girls.37 Permanent hypogonadotropic may occur The relation between PCOS and adult-onset diseases as an isolated hypothalamic-pituitary deficiency (eg, is now recognized. For example, girls and women with Kallman’s with or without cleft lip and/or palate) and PCOS are at increased risk for developing impaired glu- may be associated with a variety of molecular genetic cose tolerance (IGT) and type 2 diabetes in comparison defects. All are congenital anomalies that are associated with unaffected women; however, the clinical manifes- with multiple pituitary hormone deficiencies, not just tations of hyperandrogenemia (anovulation, , those that affect puberty onset. Not all cases of delayed acne, and androgenic alopecia) differentiate PCOS from puberty have a known genetic cause, such as those that type 2 diabetes and . Obese adolescent girls with arise from head trauma or . Primary gonadal PCOS have greater insulin resistance than obese girls failure is associated with hypergonadotropism and is without PCOS.38 In PCOS, IGT, and type 2 diabetes, caused by numerous congenital or acquired disorders impaired metabolic activity leads to suppression of insu- with a genetic (eg, gonadal dysgenesis, Klinefelter syn- lin-mediated glucose uptake and lipolysis, leading to drome, molecular genetic defects of the steroidogenic compensatory hyperinsulinemia. pathway, galactosemia) or environmental cause (eg, go- Potential mechanisms underlying PCOS include (1) nadotoxic [alkylating chemotherapy im- early origins or in utero programming stemming from pairs but rarely affects Leydig cell func- exposures during critical windows of development,39 tion], radiotherapy, surgery). Autoimmune disorders (2) LH hypersecretion, (3) primary ovarian abnormal- can cause delayed puberty through 2 different mecha- ity, (4) dysregulation of fat metabolism and adipogen- nisms: hypogonadotropic hypogonadism as a result of esis, and/or (5) dysregulation of the inflammatory hypophysitis or primary gonadal failure as a result of axis. Data arising from girls who present clinically autoimmune gonadal destruction. with CAH40 and nonhuman female primates that are exposed in utero to androgens39,41,42 are suggestive of Polycystic Ovary Syndrome prenatal programming of gonadotropin secretory dy- PCOS is a common heterogeneous disorder that affects namics and PCOS. Women with CAH and PCOS have 5% to 10% of reproductive-aged women. Insulin resis- accelerated episodic release of LH and increased hy- tance/hyperinsulinemia occurs in 50% to 60% of PCOS- pothalamic release of GnRH.40 affected women compared with a prevalence of 10% to The persistence of the hyperandrogenic phenotype in 25% in the general population. Criteria for diagnosing cultured theca cells derived from women with PCOS PCOS vary and were defined by the 1990 National In- suggests the possibility of a primary ovarian abnormality stitutes of Health–National Institute of Child Health and in PCOS43 possibly with an in utero origin.44 Investiga- Human Development conference as including chronic tion into the mechanism(s) responsible for insulin resis- anovulation and hyperandrogenism (including acne, tance in type 2 diabetes has suggested that abnormalities hirsutism, and male pattern baldness) after exclusion of in fatty acid uptake and use lead to increased plasma free other disorders, such as congenital adrenal hyperplasia fatty acid concentrations followed by ectopic fat storage (CAH), hypercortisolism, and hyperprolactinemia.34 The in skeletal muscle and liver; this aberrant fat storage more recent “Rotterdam criteria” for PCOS35 expanded (lipotoxicity) alters insulin signaling, insulin metabo-

PEDIATRICS Volume 121, Supplement 3, February 2008 S195 Downloaded from www.aappublications.org/news by guest on September 29, 2021 lism, and pancreatic ␤-cell insulin secretion, leading to some natural products such as isoflavonoids, flavonoids, the development of insulin resistance with compensa- stilbenes, , , and (eg, tory hyperinsulinemia. Oxidative stress may also con- , , , 8-prenylnaringenin, tribute to the development of insulin resistance. Activa- ). Gestational and lactational maternal oral tion of the NF-␬B/I␬B-␣/IKK-␤ pathway, a major exposure to dosages as low as 25 mg/kg per day me- pathway for inflammatory processes, by free fatty acid thoxychlor resulted in an earlier age of VO and first provides a potential link among coronary artery disease, estrus in the female rat.51 This was found to be pseudo- type 2 diabetes, insulin resistance, and PCOS.45 Familial precocious rather than true precocious puberty because clustering of IGT, type 2 diabetes, and PCOS suggests a VO was accelerated but the onset of estrous cyclicity was role for genetic determinants of this metabolic pheno- not affected. Similarly, prenatal subcutaneous injections type or in utero events such as decrements in fetal of BPA,52,53 genistein,53 resveratrol,53 ,53 or growth as measured by reduced birth size.46 The hetero- DES53 accelerated VO in mice. Although prenatal oral geneity of PCOS may account for the lack of candidate exposure to BPA did not significantly accelerate the age genes identified to date.47 at VO or first estrus in either the rat or mouse, prenatal oral treatment of mice with BPA significantly reduced the number of days between VO and first vaginal es- ENVIRONMENTAL INFLUENCES ON PUBERTY trus.54 When female rats were exposed after weaning Consistent with our definition, environmental factors throughout puberty to like methoxy- are defined to include both EDCs and body shape and chlor51 or 17 beta estradiol,56 early puberty onset was adiposity. Consistent with the focus of the workshop, induced as measured by age at VO in the female rat.55 In this review focuses on single chemicals by mode of ac- addition, prenatal BPA exposure resulted in altered mat- tion. A more comprehensive review describing the tox- uration of the mammary gland at puberty and increased icology of puberty in rodents is found elsewhere.48,49 sensitivity to endogenous .7 Last, this review urges caution in assessing an individual (AR) antagonists (also called an- pubertal marker given the highly interrelated and time- drogen antagonists) compete with natural hormones dependent nature of pubertal onset and progression as testosterone and for binding to the orchestrated by gonadal hormones under the control of AR. Thus, a decrease in binding between the natural gonadotropins. In the presence of exogenous endocrine- ligand and receptor occurs, which in turn inhibits AR- active agents, pubertal markers can be independently dependent gene expression in vivo. AR antagonist ex- induced or blocked so that they are not necessarily in posure in vivo can induce malformations in male repro- synchrony with centrally regulated pubertal maturation. ductive tract and delay puberty in the male rat. AR For example, peripubertal exposure to the gonadotropin antagonists include insecticides, herbicides, , agonist Lupron and the estrogenic agent toxic chemicals, and combustion byproducts. HPTE has both delayed menarche in monkeys, but other markers of also been shown to act as an AR antagonist.57 Peripuber- puberty were delayed or accelerated depending on the tal exposure to the AR antagonists or agent.9,50 Therefore, the relative timing of all puberty-onset led to a delayed puberty in males as mea- markers is the most informative, which argues for a com- sured by the age of PPS in the rat.51,58 plete pubertal assessment and related deviations in lieu of Conversely, AR agonists (also called androgen ago- extreme categorization such as precocious puberty. nists) compete with the endogenous hormones testos- terone and dihydrotestosterone for AR, leading to an Animal Studies increase in AR-DNA binding in vitro and AR-dependent A summary of selected examples of single environmen- gene expression in vivo. Such environmental androgen tal chemicals whose exposure at specific dosages may contaminants induce malformations in the female repro- lead to puberty-timing alterations is presented in Table ductive tract59,60; accelerate male puberty in the rat61; and 1. This table is organized by mode of action (MOA). have been associated with the masculinization of female (ER) agonists (also called estrogen fish in the United States, Sweden, and New Zealand.62 agonists or estrogens) and ER antagonists compete with Other receptors, including orphan receptors, are the the endogenous estrogen hormones estradiol and es- targets of certain environmental agents. The environ- trone for binding to the classical ER. Such agonists and mental chemical 2,3,7,8-tetrachlorodibenzo-p-dioxin antagonists bind to the ER and activate or repress, re- (TCDD) has 1 of the best-characterized MOAs, binding spectively, transcription of ER-dependent genes and to the aryl hydrocarbon (Ah) receptor that in turn ini- thereby enhance or diminish estrogenic activity in vivo tiates Ah-dependent gene expression changes. Even low (eg, induce uterine weight increase/decrease, accelerate/ dosages of TCDD in utero can lead to gene expression delay puberty). After in utero exposure to a potent es- changes and malformations in the reproductive tract in trogen agonist, gross reproductive malformations may rodents.63–67 Ah receptor ligands other than TCDD include result in female rats, presumably by altering the devel- other polychlorinated dibenzodioxins and some polychlo- opment of reproductive organs that are responsive to rinated biphenyls (PCBs), polybrominated diphenyl ethers, estrogen action. Examples of estrogen agonists that are and contaminants as well as the pesticide metho- present as environmental contaminants include 2,2- prene, a juvenile hormone agonist. Exposure to TCDD in bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), a utero caused delayed puberty in male and female rats as metabolite of the pesticide chemical methoxychlor, and measured by an older age at acquisition of PPS and VO,

S196 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 TABLE 1 Examples of Published Studies of Chemical Exposures With Puberty-Timing Effects in Animals MOA Chemical Species, Treatment Interval Effects (at Dosages) Reference(s) Gender ER agonist E2 Rat, female Peripubertal Early VO (2 and 4 mg/kg per d) Marty et al56 (1999) ER agonist DES Rhesus monkey, Peripubertal Early sex skin swelling and reddening; Golub et al50 (2003) female delayed nipple growth; completely suppressed menarche; increased serum estrogen activity (0.5 mg/kg per d) ER agonist BPA Mice, female In utero Increased lateral branching at 3 mo (25 Munoz de Toro124 (2005) and 250 ng/kg per d) ER agonist BPA Mice, female In utero stage–like mammary gland Markey et al7 (2001) differentiation (25 and 250 ng/kg) at PND 10, 1 mo, 6 mo ER agonist BPA Mice, female In utero Reduced interval between VO and first Howdeshell et al54 vaginal estrus (dose) (1999) ER agonist and AR Methoxychlor Rat, female and Peripubertal Female: early VO and first estrus (25, 50, Gray et al51 (1989) antagonist male 100, 200 mg/kg per d); VO was accelerated, but first estrus was not; F1 exposed in utero and but not directly; VO acceleration noted Male: delayed PPS (100 and 200 mg/kg per d) ER agonist and AR Methoxychlor Rhesus monkey, Peripubertal Early sex skin swelling and reddening; Golub et al50 (2003) antagonist female delayed nipple growth and menarche; increased serum estrogen activity (25 or 50 mg/kg per d) AR antagonist Vinclozolin Rat, male Peripubertal Delayed PPS (30 and 100 mg/kg per d) Monosson et al58 (1999) AR antagonist p,pЈ-DDE Rat, male Peripubertal (PND 22–55) Delayed PPS at 100 mg/kg per d Ashby and Lefevre118 (2000) AR antagonist p,pЈ-DDE Rat, male Peripubertal (PND 22–55) Delayed PPS at 30 and 100 mg/kg per d Kelce et al116 (1995) Ah agonist TCDD Rat, female in utero Delayed VO and decreased/incomplete Gray and Ostby66 (1995); mammary epithelial differentiation Gray et al64 (1997); (0.8–1.0 ␮g/kg per d) Fenton et al8 (2002) inhibitor Fadrozole Rat, female Peripubertal Delayed VO (0.6, 1.2, and 6.0 mg/kg per d) Marty et al56 (1999) Steroidogenesis inhibitor Rat, female Peripubertal Delayed VO (100 mg/kg per d) Marty et al56 (1999) Steroidogenesis inhibitor Prochloraz Rat, male Peripubertal Delayed PPS (125 mg/kg per d) Blystone et al73 (2007) CNS-HPG; reduces LH Rat, male Peripubertal Delayed PPS (12.5, 50, 100, 150, 200 mg/ Stoker et al48,68 (2000) and kg per d) CNS-HPG; reduces LH Atrazine Rat, female Peripubertal Delayed VO (50, 100 and 200 mg/kg per d) Laws et al69 (2000) and prolactin GnRH agonist Leuprolide acetate Rhesus monkey, Prepubertal Blocked menarche; delayed body growth Golub et al9 (1997) female (weight and height); decreased muscle mass; increased serum IGF-1 (0.75 mg/ kg per month) E2 indicates 17␤ -estradiol; DES, diethylstilbestrol; CNS, central nervous system; PND, postnatal day; IGF-1, insulin-like growth factor 1. respectively,64–67 and a delayed or incomplete differentia- tricular preoptic area at 22 to 24 days of age (prepuber- tion of mammary epithelium.8 tal), an important brain region that regulates estrous Some environmental chemicals affect puberty via cyclicity and estrogen-positive feedback.71 MOAs that are involved in the central nervous system/ Chemicals that inhibit the synthesis of endogenous HPG axis, altering brain, hypothalamic, and/or pituitary hormones (eg, testosterone, 17␤-estradiol, adrenal ste- function via direct interactions with the central nervous roids) typically do so by competitively inhibiting the system neuroendocrine function. These include the pes- activity of Ն1 P450 steroidogenic enzymes. The predom- ticides thiram, molinate, metam sodium, chlordime- inant effects are mediated through the steroidogenic form, amitraz, , dichloroacetic acid, atrazine, enzymes cholesterol side chain cleavage enzyme, steroid propazine, simazine, methanol, and . Prepubertal 17,20 lyase, and aromatase (which converts androgens exposure to atrazine causes delayed puberty in the male to estrogens). Some affect estrogen synthesis preferen- and the female, as evidenced by an older age at acqui- tially over testosterone or adrenal hormones, and others sition of PPS68 and VO,69 respectively. The modes of affect adrenal and liver function. Examples of environ- action for atrazine’s reproductive effects include puberty mental and pharmaceutical aromatase inhibitors include timing and a reduction in circulating LH and prolactin.70 conazole and imadazole fungicides (eg, prochloraz, fe- Perinatal exposure of mice to BPA results in a decrease of narimol, ketoconazole, fadrozole). Peripubertal expo- tyrosine hydroxylase neurons in the rostral periven- sure to the fadrozole at dosages as

PEDIATRICS Volume 121, Supplement 3, February 2008 S197 Downloaded from www.aappublications.org/news by guest on September 29, 2021 low as 0.6 mg/kg per day led to a delayed VO in female pubic hair development compared with unexposed girls or rats.56 Peripubertal exposure to 100 mg/kg per day of the girls who were not breastfed. There was no association steroidogenesis inhibitor ketoconazole also led to a de- found with Tanner stage of breast development. layed VO.56 The MOA of prochloraz is the inhibition of Various studies have evaluated pubertal development aromatase72 and 17,20 lyase73,74 apparently directly in- among children who were exposed to DDT and its pri- hibiting steroidogenesis of estrogens and androgens. Pro- mary metabolite DDE. Two studies specifically assessed chloraz also delays puberty in male rats.73 The MOA of developmental exposure (in utero and/or postnatal via the chemical ketoconazole is inhibition of side- lactation) within a cohort. Gladen et al97 conducted a chain cleavage enzyme (SCC), progesterone, and adre- prospective cohort study of boys and girls who resided in nal steroid synthesis. The MOA of many es- North Carolina in relation to DDE concentrations that ters, including diethylhexyl phthalate, dibutyl phthalate, were previously measured in the mothers’ serum, cord and benzyl butyl phthalate, is to inhibit fetal testis Leydig serum, and the placenta (averaged for in utero expo- cell steroidogenesis and insl3 synthesis, leading to male sure). Concentrations in breast milk also were deter- developmental and malformations mined (lactational exposure). Puberty-timing measures, (eg, retained nipples, reduced or absent reproductive or- Tanner stages (boys and girls), and menarche were as- gans, undescended testes, hypospadias, delayed PPS) with sessed by annual questionnaires. For boys, no associa- in utero exposure and delays in puberty with peripubertal tion was observed for either in utero or lactational DDE exposure.75 Administration of during puberty to exposure. Among girls, there was no association with marmosets induced ovarian and uterine alterations in fe- age at menarche; however, there was a suggestion of an males and reduced peripubertal testosterone levels in association of higher in utero or lactational exposure and 76 males ; however, the effect on androgen levels was not earlier breast and pubic hair development that was not significant because of the extreme variability in this mea- statistically significant. Vasiliu et al98 also evaluated in sure in this species. utero exposure to DDT/DDE that was estimated using a decay model based on maternal measurements among Human Studies daughters of a Michigan angler cohort. The authors ob- Many human studies have shown a positive relation served a significantly earlier menarche among girls with between body fat, primarily measured by BMI or skin- an increased in utero exposure. Specifically, menarche fold thickness, and onset of puberty, as determined by was 1 year earlier for every 15-␮g/L increase in in utero the onset of the growth spurt, breast development, or exposure. No association was seen with menarche.77–84 Similar findings are observed in boys as and age at menarche. measured by growth spurt or genital and pubic hair mat- Several additional studies evaluated DDT/DDE expo- uration.81,85–87 Body size measures also have been associ- sure in childhood using various designs. Krstevska-Kon- ated with early puberty,82,86,88 as have dietary and physical stantinova et al99 measured DDE concentration among activity exposures and pubertal timing.79,89–94 Environmen- tal exposure to persistent halogenated organic chemicals girls who were born in Belgium compared with those such as PCBs, dichlorodiphenyltrichloroethane/dichlorodi- who were foreign-born. The foreign-born girls had sig- phenyldichloroethylene (DDT/DDE), and brominated nificantly higher levels of DDE that were correlated with flame retardants have been associated with pubertal alter- age at immigration and time since immigration than ations, as have dioxin, hexachlorobenzene (HCB), en- native-born girls. Other migratory effects have been seen 100 dosulfan, and heavy metals, but to a lesser extent (Table 2). in other populations. They also estimated the inci- The first study to report that timing of puberty was dence of precocious puberty among native Belgium girls associated with developmental exposure to persistent and foreign adopted girls from vital records and adoption organic pollutants was conducted among a cohort of registries and found the rate of precocious puberty to be individuals who were exposed to brominated flame re- 80 times higher than that for native-born Belgium girls. tardants.95 An industrial accident resulted in the contam- Although suggestive, this preliminary study was limited ination of cattle feed with polybrominated biphenyls and in size and scope, especially with regard to other differ- widespread human exposure through consumption of ences unaccounted for between the 2 groups of children. meat and dairy products. Daughters of women who Ouyang et al101 studied newly married female textile consumed contaminated farm products were inter- workers in China by measuring serum DDT/DDE con- viewed or completed a self-administered mailed ques- centration. Women were asked to recall age at men- tionnaire. Age at menarche and Tanner stages (for those arche. A significant dose-response relation was found who were younger than 18 years) were assessed. Ma- between serum DDT/DDE concentrations and earlier ternal serum levels of at the menarche. A 10 ng/g increase in exposure was associ- time of conception were estimated from a decay model ated with 0.2 years earlier onset of menarche. Because using serum concentrations that were measured before exposure occurred after pubertal development was com- and/or after the pregnancy.96 Girls who were exposed in plete, the causal order of exposure-puberty cannot be utero to high concentrations (Ն7 ppb) and who were established because pubertal development may have af- breastfed reported menarche 1 full year earlier than unex- fected the metabolism/distribution of DDT or other be- posed girls (Ͻ1 ppb, the limit of detection) or girls who haviors that influenced DDT exposure. Denham et al102 were exposed in utero but not breastfed. Breastfed girls conducted a cross-sectional study among girls who were with high in utero exposure also reported more advanced aged 10 to 17 years and resided in the Mohawk Nation

S198 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 TABLE 2 Human Studies That Assessed Associations Between Environmental Chemical Exposures and Puberty Timing Chemical Exposure Population (Sample Size) Study Design Findings Reference (Biospecimen) Brominated flame US, Michigan girls aged 5–24, CS/C; assessment of Tanner stages Earlier menarche and pubic hair Blanck et al95 (2000) retardant (estimated accidental in utero and/or in female offspring; recalled age development among girls maternal serum PBB at lactational exposure (327) at menarche in postmenarchal highly exposed in utero and conception) offspring breastfed; no association with breast development DDE (maternal blood, cord US, North Carolina boys and C; assessed menarche, Tanner Boys: no association; girls: Gladen et al97 (2000) blood, and placenta girls (594) stages by annual questionnaire suggestion of earlier breast averaged; breast milk) and pubic hair development with high transplacental and with high lactational exposure DDE (serum) Girls with precocious puberty: CS; serum DDE compared Foreign-born girls with Krstevska-Konstantinova foreign-born girls (26); between foreign-born and precocious puberty had et al99 (2001) Belgium girls (15) Belgium girls; all had significantly higher DDE precocious puberty concentration than native Belgium girls with precocious puberty. DDE (estimated maternal US, Michigan daughters of C; recalled age at menarche Higher DDE associated with Vasiliu et al98 (2004) serum DDE at women who consumed earlier menarche. conception) Great Lakes fish (151) DDT/DDE (serum in Chinese female textile CS; recalled age at menarche Higher DDT/DDE associated Ouyang et al101 (2005) adulthood) workers, newly married with earlier menarche (466) DDE (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) No association Denham et al102 (2005) girls 10–17 (138) Dioxin-like activity 17-y-old Belgium boys (78) CS; assessment of Tanner stage by Boys: no association; girls: girls Den Hond et al106 (2002) (serum; CALUX) and girls (120) from examination (boys and girls), with high exposure were less polluted and nonpolluted testicular volume (boys), likely to have reached the areas recalled age at menarche (girls). highest stage of breast development; no association with pubic hair development or age at menarche. Dioxin (serum) Seveso, Italy, women C; recalled age at menarche No association; suggestion of Warner et al108 (2004) exposed postnatally and earlier menarche among girls prepuberty to dioxin exposed before the age of 5 industrial accident (282) India, boys aged 10–17 in C/CS; Tanner stage by physical Exposed boys were less mature Saiyed et al111 (2003) exposed (117) and examination; serum hormones and had lower testosterone unexposed (90) areas and endosulfan levels for 70 and higher LH than exposed, 45 unexposed. unexposed boys HCB (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) No association Denham et al102 (2005) girls 10–17 (138) Lead (serum) US 8- to 16-y-old girls CS, assessed age at menarche and Later pubic hair and breast Selevan et al112 (2003) NHANES III (2186) Tanner stages; analyses development associated stratified by ethnic groups with higher lead among blacks and Mexican Americans, suggested association among non- Hispanic whites; later menarche associated with higher lead among blacks, suggested association among Mexican Americans and non-Hispanic whites Lead (serum) US 8- to 16-y-old girls CS, assessed age at menarche and Later menarche and pubic hair Wu et al113 (2003) NHANES III (1706) Tanner stages development with higher lead exposure; no association with breast development Lead (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) Exposure to lead associated Denham et al102 (2005) girls 10–17 (138) with lower likelihood of menarche

PEDIATRICS Volume 121, Supplement 3, February 2008 S199 Downloaded from www.aappublications.org/news by guest on September 29, 2021 TABLE 2 Continued Chemical Exposure Population (Sample Size) Study Design Findings Reference (Biospecimen) Mercury (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) Suggestion of earlier menarche Denham et al102 (2005) girls 10–17 (138) with mercury exposure Mirex (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) No association Denham et al102 (2005) girls 10–17 (138) PCBs (serum) US/Canada Mohawk Nation, CS; menarche (yes/no) 4 potentially estrogenic PCB Denham et al102 (2005) girls 10–17 (138) congeners (52, 70, 101ϩ90, and 187) significantly associated with a greater probability of having reached menarche PCBs (maternal blood, US, North Carolina boys and C; assessed menarche, Tanner Boys: no association; girls: Gladen et al97 (2000) cord blood, and girls (594) stages by annual questionnaire suggestion of earlier breast placenta averaged; and pubic hair development breast milk) with high transplacental, suggestion of earlier pubic hair development with lactational exposure PCBs (maternal serum) US, Michigan girls aged 5–24 CS; assessment of Tanner stages; No association Blanck et al95 (2000) (256) recall of age at menarche in postmenarchal girls PCBs (cord blood) Faroe Islands boys (175) C/CS; genital anomalies at birth, No significant associations; Mol et al103 (2002) examination at age 14 for suggestion of higher Tanner stage, testicular size, testosterone with higher PCB spermaturia, and serum exposure hormones PCBs (serum; congeners 17-y-old Belgium boys (78) CS; assessment of Tanner stage by Boys: high exposure to PCB 138 Den Hond et al106 (2002) 138, 153, and 180) and girls (120) from examination and testicular less likely to have reached polluted and nonpolluted volume highest stage of genital areas development, high PCB 153 less likely to have reached highest stage of pubic hair; girls: no associations PCBs/PCDFs Taiwan, girls aged 13–19 C; recalled age at menarche, No association with age at Yang et al104 (2005) exposed to contaminated characteristics, menarche; exposed girls oil (Yucheng) in utero (27) serum hormones reported shorter cycle length and controls (21) and more irregular cycles, exposed girls had higher levels of estradiol and FSH PCBs/PCDFs Taiwan, boys (mean age: C/CS; Tanner stages by exam, No association with Tanner Hsu et al105 (2005) 12.3) exposed to testicular size, serum hormones stage or testicular size; some contaminated oil differences in hormone (Yucheng) in utero (61) levels in boys Ն13 years and controls (60) PCBs (estimated maternal US, Michigan daughters of C; recalled age at menarche No association Vasiliu et al98 (2004) serum PCBs at women who consumed conception) Great Lakes fish (151) PCBs (serum congeners) US/Canada Mohawk Nation, CS; menarche (yes/no) Exposure to estrogenic Denham et al102 (2005) girls 10–17 (138) congeners (52, 70, 90, 101, 187, geometric mean) associated with greater likelihood of menarche; no association with other congener groups Phthalates (serum) Puerto Rico (41 PT cases, 35 Case control Serum phthalate (primarily Colon et al109 (2000) controls) DEHP) significantly higher in cases than controls CS, cross-sectional study; C, cohort study; CS/C cross-sectional assessment within a cohort; CALUX, chemically activated luciferase gene expression; PBB, polybrominated biphenyl; NHANES III, Third National Health and Nutrition Examination Survey; PCDFs, polychlorinated dibenzo-furans; PT, premature thelarche. along the United States/Canadian border to assess serum sure and menarche despite the authors’ assumption that concentrations and self-reported menarchal status (yes/ current serum concentrations were indicative of in utero no). No association was observed between DDT expo- and lactational exposures, given the long-standing con-

S200 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 cern regarding consumption of contaminated fish were compared with 35 control girls with regard to among this population. serum and phthalate esters. Significantly Five studies evaluated developmental PCB exposures higher phthalate levels were found among the girls with in relation to pubertal development. Gladen et al97 re- thelarche than comparison girls. The authors concluded ported no relation between in utero or lactational PCB that the findings were suggestive of a possible associa- exposure and age at menarche among girls. Higher lac- tion between exposures and premature breast develop- tational exposure was associated with earlier Tanner ment in girls. Interpretation of these findings may be staging in boys and girls, although the results did not limited by residual confounding and concerns about the achieve statistical significance. Mol et al103 established a analytical method of measuring the phthalate parent prospective cohort study of boys in the Faroe Islands, compound instead of the metabolites.110 Saiyed et al111 where PCB levels are known to be relatively high. PCB found that boys who were exposed to endosulfan in levels were measured in cord serum and tissue. Boys India were less mature and had lower testosterone and were examined at 14 years of age for Tanner staging, higher LH than unexposed boys. testicular size, spermaturia ( in urine), and serum Three cross-sectional published articles assessed the hormones. No statistically significant associations were relation between lead exposure and pubertal measures found between PCB concentrations and measures of using either the Third National Health and Nutrition pubertal development. A suggestion of a positive associ- Examination Survey112,113 or the Mohawk Nation ation between testosterone and PCB exposure was re- Study.102 In the Third National Health and Nutrition ported. Two cohort studies previously described95,98 also Examination Survey analyses, blood lead levels were evaluated in utero exposure to PCBs among daughters of analyzed in relation to age at onset for Tanner stage 2 for women who were exposed. Neither study found an as- breast and pubic hair and menarche among US girls aged sociation between PCB exposure and age at menarche. 8 to 18 years.113 Selevan et al112 estimated odds ratios for Last, Yang et al104 and Hsu et al105 described no pubertal lead levels in relation to progression of puberty (stages developmental differences among boys or girls with and 2–5) among girls. Combined, these studies suggested an without exposure to PCB- and polychlorinated dibenzo- inverse relation between blood lead levels and the onset furan–contaminated cooking oil. and progression of puberty in girls, especially for sub- Two cross-sectional studies of PCB exposure have groups within the population. An association also was been conducted. Den Hond et al106 measured PCB con- found between higher blood lead level and delayed geners in a sample of boys and girls who were aged 17 menarche, but this association was statistically signifi- years and recruited from 1 of 2 exposed areas in Belgium: cant only for black girls. The cross-sectional analysis residence near a lead smelter or waste incinerator or a among Mohawk nation girls also found later puberty referent rural area. Puberty timing was measured using the among girls with higher lead exposures than girls with Tanner staging as a part of a physical examination. Odds lower exposure. ratios were estimated for PCB concentration and odds for being in a puberty stage that indicated that puberty was not Cross-species Concordance of Pubertal Timing Effects yet complete (ie, lower than stage 5). Exposed boys had Most chemicals have not been consistently studied in completed pubertal development later, because odds ratios both animals and humans, with a few notable excep- for higher PCB exposures (for both specific congeners and tions. Even when such research is available for a partic- total PCBs) were associated with stage Ͻ5 for genital and ular chemical, interpretation is exceedingly challenging pubic hair development. Because this study evaluated 17- given issues pertaining to dosage and timing of exposure year-olds, it is not clear whether puberty began later or the and limited measurement of other relevant covariates. peripubertal duration was longer. No pubertal delays were When such data are available (eg, TCDD, lead, DDE, seen in girls with PCB exposure. Among Akwesasne Mo- PCBs, estrogens), similar findings tend to be observed hawk Nation Girls, exposure to a group of 4 potentially across species. For example, pharmaceutical estrogens estrogenic PCB congeners (52, 70, 101 ϩ 90, and 187) was (eg, diethylstilbestrol, ethinyl estradiol) are the best ex- associated with a significantly greater likelihood of having amples of accelerated female breast development in hu- reached menarche.102 mans, but the effect tends to be reversible and isolated Two studies assessed childhood exposure to dioxins from other pubertal effects.29,30–33 This is similar to the and puberty. Den Hond et al106 measured dioxin-like effects of estrogen exposure in the female rat56 and the activity with the chemically activated luciferase gene monkey, which cause pseudoprecocious or dysregulated expression assay107 and reported an association with puberty markers.50 In male humans, pharmaceutical Tanner stage Ͻ5 breast development; however, pubic agents that are used to halt early puberty also cause hair stage in boys and girls and genital stage in boys was similar effects in male rats. In the rat, in utero TCDD not significantly associated with dioxin-like activity. exposure resulted in delayed puberty as measured by a Warner et al108 examined pubertal development among late age of VO and a delayed or incomplete differentia- girls who were exposed postnatally or during childhood tion of mammary epithelium.8 Similarly, Den Hond et to dioxin in Seveso, Italy. TCDD was not associated with al106 reported an association between high dioxin blood age of menarche (self-reported at interview). None of levels and later completion of breast development. This the women was exposed prenatally. cross-species concordance may indicate that the Ah recep- Colon et al109 studied phthalate esters exposure and tor agonism is active across species. For developmental lead premature thelarche. Forty-one girls with thelarche exposure, animal and human studies both show a delay in

PEDIATRICS Volume 121, Supplement 3, February 2008 S201 Downloaded from www.aappublications.org/news by guest on September 29, 2021 TABLE 3 Research Recommendations for Focusing on Environmental Influences on Puberty Priority Research Questions Recommended Studies Recommended Species Etiologic Research 1. Are environmental levels of EDCs Prospective epidemiologic research inclusive of Humans affecting onset and progression existing cohort currently being followed (eg, of puberty and aberrant Seveso, Yucheng, Yusho, PBB, DES pubertal development such as grandchildren) or newly designed delayed or precocious puberty epidemiologic research capturing in children? environmentally relevant exposures (single chemical and mixtures) Cross-sectional studies for monitoring population changes particularly across geographic areas and inclusive of high-risk subgroups of the population 2. Do body shape and adiposity Prospective epidemiologic research inclusive of Humans affect onset and progression of existing cohort currently being followed puberty and aberrant pubertal (eg, Seveso, Yucheng, Yusho, PBB, DES development such as delayed or grandchildren) or newly designed precocious puberty in children? epidemiologic research capturing environmentally relevant exposures (single chemical and mixtures) Cross-sectional studies for monitoring population changes particularly across geographic areas and inclusive of high-risk subgroups of the population Critical windows of exposure 3. What are the critical windows, Prospective research comprising couples Humans and nonhuman ranging from periconception attempting pregnancy to capture parentally primates through adolescence, for human mediated exposures from periconception pubertal development in window to prospective pregnancy cohorts relation to environmental Research focusing on the early origins of exposures? human health and disease Mechanistic 4. What is the primary signal(s) for Genomics and proteomic studies using Nonhuman primates and the onset of GnRH-dependent nonhuman primates and humans with humans (central) puberty? alterations in the onset of puberty 5. What is the primary signal(s) for Genomic and proteomic studies using Rodents the onset of GnRH-independent transgenic rodent model. (peripheral) puberty? 6. What is the molecular basis for Identifying the similarities and differences in Rodents, nonhuman primates in puberty molecules involved from puberty initiation onset and progression? to final outcome (described in 4 and 5) in males and females 7. How is the tempo of puberty Environmental exposure and puberty-timing Rodents, nonhuman primates, progression including the studies that measure Ͼ1 puberty-timing humans temporal relationship among end point/outcome. the different markers regulated?

pubertal development,112–115 suggesting a similar mecha- ture of compounds to which humans are exposed. Much nism for rodents and humans. P,pЈ-DDE exposure in “for- of the data are derived from cross-sectional studies, eign-born” girls was associated with earlier puberty relative which are unable to establish the causal ordering of to native-born Belgians99 and, possibly, increasing DDE in environment in relation to puberty. To this end, timing utero exposure with earlier puberty in girls97,98; however, and dose at critical windows of human development no animal studies of DDE exposure and female puberty have not been purposefully assessed. Other relevant co- timing were identified, limiting additional interpretation of variates such as lifestyle, genetic determinants, and the human data. In male rats, peripubertal DDE exposure other xenobiotics in the chemical mixture have not been delays PPS,116–118 although no relation to lower exposures well studied, if at all, in the context of EDCs. was found in boys after in utero DDE exposure.97 The weight of animal and human data, although sug- RESEARCH RECOMMENDATIONS gestive, remains inconclusive for establishing a causal The panel was asked to make research recommendations relation between EDCs and human pubertal distur- that are responsive to critical data gaps regarding pur- bances. As reviewed, much of the available literature ported environmental factors that may adversely affect focuses on a single chemical or class, ignoring the mix- puberty, to prioritize research initiatives including meth-

S202 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 ods development, and to identify avenues for research been demonstrated.121,122 Ideally, such studies would incor- collaboration. porate longitudinal biospecimen collection at timed inter- vals for the quantification of chemical mixtures and life- style exposures that may affect growth and development Environmental Factors Identified as Important for Human inclusive of pubertal milestones. Efforts to develop a suite Puberty of sensitive pubertal markers, rather than a sole marker, After reviewing the weight of evidence described herein, that are consistent with the manner in which humans are the panel agreed that EDCs and body size or adiposity exposed are needed. Future research needs are discussed may be associated with pubertal disturbances in hu- elsewhere in this issue but underscore the need to develop mans. The panel further recognizes that the 2 broad behavioral, psychosocial, and neurologic end points along exposures may be interrelated in that exposure to EDCs with the social and psychological consequences of preco- can affect fat metabolism (eg, organotin compounds and cious or delayed puberty.11 diethyl hexyl phthalate act as peroxisome proliferator– Last, regardless of the research question, newly de- activated receptor agonists in adipose tissue). Although signed animal and human research must use the best humans can do little to minimize exposure to ubiquitous available methods. With regard to animal research, care- EDCs other than change dietary practices, particularly ful attention to choice of the most appropriate animal with regard to fish consumption and preparation, body model, relevant critical or sensitive windows of expo- size is potentially amenable to behavioral intervention. sure, route and duration of exposure, timing and rele- Carefully designed epidemiologic research, particularly vant dosages, assumptions regarding the dose-re- that with longitudinal capture of exposures and relevant sponse curve, and an analytic statistical plan that is covariates at critical windows and the sensitive and spe- responsive to the study design, particularly assessment cific measurement of markers of pubertal onset, progres- of mixtures and litter effects, is needed. Epidemiologic sion, or deviations from expected normative standards, research also needs to address these same issues while is needed to answer remaining questions about the role recognizing the highly correlated nature of reproduc- of environmental influences on developmental mile- tive outcomes and the need to model appropriately stones. Such studies are rightfully complex and require a previous history of adverse reproductive outcomes, a priori consideration and capture of other environmental strong predictor, in the context of more subtle envi- determinants of puberty such as those that are believed ronmental effects.123 to be attributed to body size and composition and pos- sible genotypes and phenotypes that may emerge. Fur- ther complicating future research will be the challenges CONCLUSIONS afforded by environmental mixtures, including those A concerted body of multidisciplinary research is needed that arise from “natural” sources such as phytoestrogens. to answer lingering questions about the impact of EDCs, body size, and adiposity on human puberty. This re- search can be grounded within a broader research base Research Priorities and Future Directions inclusive of given the highly interre- The panel identified 7 priority research questions reflect- lated and timed series of critical events that are character- ing 3 broad research domains: etiologic, exposure assess- istic of human growth and development, of which puberty ment, and mechanistic (Table 3). The panel strongly is 1 of many key milestones. Basic research targeting the supported additional etiologic work aimed at answering primary signals for onset is critical so that epidemiologic lingering questions about the impact of EDCs and body investigators can design research that is sensitive to the size and adiposity on the onset and progression of pu- capture and measurement of key biomarkers of pubertal berty and aberrant clinical manifestations (ie, delayed or onset. Additional basic research is needed regarding com- precocious puberty). The natural history of puberty re- parative species physiology of puberty, the primary signal quires delineation and ordering of a multitude of factors of puberty onset for central versus peripheral signaling, and such as lipids, body shape, and diet in relation to puber- the basis for sexual dimorphism. tal onset and progression. With regard to exposure as- sessment, continued work is needed to capture the tim- ing and dosage of maternal, paternal, or parental ACKNOWLEDGMENTS exposures across sensitive and critical windows of hu- Support for “The Role of Environmental Factors on the man development to identify agents that may disrupt Onset and Progression of Puberty” workshop was pro- normal embryonic or fetal development resulting in fetal vided by US Environmental Protection Agency coop- (re)programming with lifetime effects.119,120 Last, the erative agreement 830774, the National Institute of panel continued to support basic research to identify the Environmental Health Sciences, and Serono Inc. primary signal(s) for the onset of GnRH-dependent and We gratefully acknowledge Serono Symposia Inter- GnRH-independent puberty in humans, nonhuman pri- national and David Schlumper for organizing and hold- mates, and other animals. ing “The Role of Environmental Factors on the Onset The increasing methodologic complexities that are as- and Progression of Puberty” Expert Panel Workshop. In sociated with capturing exposures, including environmen- addition, we thank the other members of the Expert tal mixtures, in the context of lifestyle and behavior across Panel for participating in the discussions: Carlos critical windows of human development argue for prospec- Bourdony, Farid Chehab, Gwen Collman, Ralph Cooper, tive epidemiologic studies whose utility and feasibility have Leo Dunkel, Paul Foster, Beth Gladen, Mari Golub, Mel

PEDIATRICS Volume 121, Supplement 3, February 2008 S203 Downloaded from www.aappublications.org/news by guest on September 29, 2021 Grumbach, Marcia Herman-Giddens, John Himes, genast A. Glia-to neuron signaling and the neuroendocrine Anders Juul, Paul Kaplowitz, Carole Kimmel, Peter Lee, control of female puberty. Ann Med. 2003;35(4):244–255 Robert Lustig, Tony Plant, Ed Reiter, Steve Schrader, 20. Ojeda SR, Lomniczi A, Mungenast A, et al. Towards under- Sherry Selevan, Richard Sharpe, Thorkild Sørensen, and standing the neurobiology of mammalian puberty: genetic, Patricia Whitten. We especially thank Anders Juul for genomic and proteomic approaches. In: Kordon C, Gaillard R, Christen Y, eds. Hormones and the Brain. Berlin, Germany: critical reading of the manuscript. Springer; 2005:47–60 21. Ojeda SR, Lomniczi A, Mastronardi C, Heger S, Roth C, Parent REFERENCES AS. Mini-review: the neuroendocrine regulation of puber- 1. Rockett JC, Johnson CD, Buck GM. Biomarkers for assessing ty—is the time ripe for a systems biology approach? Endocri- reproductive development and health: part 1—pubertal de- nology. 2006;147(3):1166–1174 velopment. Environ Health Perspect. 2004;112(1):105–112 22. de Roux N, Genin E, Carel J-C, Matsuda F, Chaussain J-L, 2. Marshall WA, Tanner JM. Variations in pattern of pubertal Milgrom E. Hypogonadotropic hypogonadism due to loss of changes in girls. Arch Dis Child. 1969;44(235):291–303 function of the KiSS1-derived peptide receptor GPR54. Proc 3. Marshall WA, Tanner JM. Variations in the pattern of puber- Natl Acad Sci USA. 2003;100(19):10972–10976 tal changes in boys. Arch Dis Child. 1970;45(239):13–23 23. Seminara SB, Messager S, Chatzidaki EE, et al. The GPR54 4. Arlt W, Martens JW, Song M, Wang JT, Auchus RJ, Miller gene as a regulator of puberty. N Engl J Med. 2003;349(17): WL. Molecular evolution of adrenarche: structural and func- 1614–1627 tional analysis of p450c17 from four primate species. Endocri- 24. Mastronardi C, Smiley GG, Raber J, Kusakabe T, Kawaquchi nology. 2002;143(12):4665–4672 A, Matagne V. Deletion of the Ttf1 gene in differentiated 5. Conley AJ, Pattison JC, Bird IM. Variations in adrenal andro- neurons disrupts female reproduction without impairing gen production among (nonhuman) primates. Semin Reprod basal ganglia function. J Neurosci. 2006;26(51):13167–13179 Med. 2004;22(4):311–326 25. Cottrell EC, Campbell RE, Han SK, Herbison AE. Postnatal 6. Ojeda SR, Skinner MK. Puberty in the rat. In: Neill JD, ed. The remodeling of dendritic structure and spine density in gonado- Physiology of Reproduction. 3rd ed. San Diego, CA: Academic tropin-releasing hormone neurons. Endocrinology. 2006; Press/Elsevier; 2006:2061–2126 147(8):3652–3661 7. Markey CM, Luque EH, Munoz De Toro M, Sonnenschein C, 26. Funes S, Hedrick JA, Vassileva G, et al. The KiSS-1 receptor Soto AM. In utero exposure to alters the devel- GPR54 is essential for the development of the murine repro- opment and tissue organization of the mouse mammary ductive system. Biochem Biophys Res Commun. 2003;312(4): gland. Biol Reprod. 2001;65(4):1215–1223 1357–1363 8. Fenton SE, Hamm JT, Birnbaum LS, Youngblood GL. Persis- 27. Henley DV, Lipson N, Korach KS, Bloch CA. Prepubertal tent abnormalities in the rat mammary gland following ges- gynecomastia linked to lavender and tea tree oils. N Engl tational and lactational exposure to 2,3,7,8-tetrachloro- J Med. 2007;356(5):479–485 dibenzo-p-dioxin (TCDD). Toxicol Sci. 2002;67(1):63–74 28. Witchel SF, Plant TM. Puberty: gonadarche and adrenarche. 9. Golub MS, Styne DM, Wheeler MD, et al. Growth retardation In: Strauss JF, Barbieri RL, eds. Yen and Jaffe’s Reproductive in premenarchial female rhesus monkeys during chronic ad- Endocrinology. 5th ed. Philadelphia, PA: Elsevier Saunders; ministration of a GnRH agonist (leuprolide acetate). J Med 2004:493–535 Primatol. 1997;26(5):248–256 29. Hertz R. Accidental ingestion of estrogens by children. Pediat- 10. Terasawa E, Fernandez DL. Neurobiological mechanisms of rics. 1958;21(2):203–206 the onset of puberty in primates. Endocr Rev. 2001;22(1): 30. Beas F, Vargas L, Spada RP, Merchak N. Pseudoprecocious 111–151 puberty in infants caused by a dermal ointment containing 11. Golub MS, Germann SL, Hogrefe CE. Endocrine disruption estrogens. J Pediatr. 1969;75(1):127–130 and cognitive function in adolescent female rhesus monkeys. 31. Edidin DV, Levitsky LL. Prepubertal gynecomastia associated Neurotoxicol Teratol. 2004;26(6):799–809 with estrogen-containing hair cream. Am J Dis Child. 1982; 12. Van Wagenen G, Simpson ME. Testicular development in the 136(7):587–588 rhesus monkey. Anat Rec. 1954;118(2):231–251 32. Felner EI, White PC. Prepubertal gynecomastia: indirect ex- 13. Gray LE Jr, Wilson V, Noriega N, et al. Use of the laboratory posure to estrogen cream. Pediatrics. 2000;105(4). Available rat as a model in screening and testing. at: www.pediatrics.org/cgi/content/full/105/4/e55 ILAR J. 2004;45(4):425–437 33. Tiwary CM. Premature sexual development in children fol- 14. Foster DL, Padmanabhan V, Wood RI, Robinson JE. Sexual lowing the use of estrogen- or placenta-containing hair prod- differentiation of the neuroendocrine control of gonadotro- ucts. Clin Pediatr (Phila). 1998;37(12):733–739 phin secretion: concepts derived from sheep models. Reprod 34. Zawadski J, Dunaif A. Diagnostic criteria for polycystic ovary Suppl. 2002;59:83–99 syndrome: towards a rational approach. In: Dunaif A, Givens 15. Plant TM, Witchel SF. Puberty in nonhuman primates and JR, Haseltine F, eds. Polycystic Ovary Syndrome. Oxford, humans. In: Neill JD, ed. The Physiology of Reproduction. 3rd ed. England: Blackwell Science Ltd; 1992:377–384 San Diego, CA: Academic Press/Elsevier; 2006:2177–2230 35. The Rotterdam ESHRE/ASRM-Sponsored PCOS consensus 16. Richter TA, Terasawa E. Neural mechanisms underlying the workshop group: Revised 2003 consensus on diagnostic cri- pubertal increase in LHRH release in the rhesus monkey. teria and long-term health risks related to polycystic ovary Trends Endocrinol Metab. 2001;12(8):353–359 syndrome (PCOS). Hum Reprod. 2004;19(1):41–47 17. Plant TM. The male monkey as a model for the study of the 36. Witchel SF. Puberty and polycystic ovary syndrome. Mol Cell neurobiology of puberty onset in man. Mol Cell Endocrinol. Endocrinol. 2006;254–255:146–153 2006;254–255:97–102 37. Iban˜ez L, Virdis R, Potau N, et al. Natural history of premature 18. Ojeda SR, Terasawa E. Neuroendocrine regulation of puberty. pubarche: an auxological study. J Clin Endocrinol Metab. 1992; In: Pfaff D, Arnold A, Etgen A, Fahrbach S, Moss R, Rubin R, 74(2):254–257 eds. Hormones, Brain and Behavior. NY: Elsevier; 2002: 38. Lewy VD, Danadian K, Witchel SF, Arslanian S. Early meta- 589–659Vol 4. New York bolic abnormalities in adolescent girls with polycystic ovarian 19. Ojeda SR, Prevot V, Heger S, Lomniczi A, Dziedzic B, Mun- syndrome. J Pediatr. 2001;138(1):38–44

S204 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 39. Abbott DH, Barnett DK, Bruns CM, Dumesic DA. Androgen estradiol, steroid inhibitors, and a thyroid inhib- excess fetal programming of female reproduction: a develop- itor. Toxicol Sci. 1999;52(2):269–277 mental aetiology for polycystic ovary syndrome? Hum Reprod 57. Maness SC, McDonnell DP, Gaido KW. Inhibition of androgen Update. 2005;11(4):357–374 receptor-dependent transcriptional activity by DDT isomers 40. Barnes RB, Rosenfield RL, Ehrmann DA, et al. Ovarian hy- and methoxychlor in HepG2 human hepatoma cells. Toxicol perandrogynism as a result of congenital adrenal virilizing Appl Pharmacol. 1998;151(1):135–142 disorders: evidence for perinatal masculinization of neuroen- 58. Monosson E, Kelce WR, Lambright C, Ostby J, Gray LE Jr. docrine function in women. J Clin Endocrinol Metab. 1994; Peripubertal exposure to the antiandrogenic fungicide, vin- 79(5):1328–1333 clozolin, delays puberty, inhibits the development of andro- 41. Dumesic DA, Schramm RD, Abbott DH. Early origins of poly- gen-dependent tissues, and alters androgen receptor function cystic ovary syndrome. Reprod Fertil Dev. 2005;17(3):349–360 in the male rat. Toxicol Ind Health. 1999;15(1–2):65–79 42. Zhou R, Bird IM, Dumesic DA, Abbott DH. Adrenal hyper- 59. Hotchkiss A, Lambright CS, Ostby JS, Parks-Saldutti L, Van- androgenism is induced by fetal androgen excess in a rhesus denbergh JG, Gray LE Jr. Prenatal testosterone exposure monkey model of polycystic ovary syndrome. J Clin Endocrinol permanently masculinizes anogenital distance, nipple devel- Metab. 2005;90(12):6630–6637 opment and reproductive tract morphology in female 43. Wickenheisser JK, Nelson-DeGrave VL, McAllister JM. Hu- Sprague-Dawley rats: testosterone-induced malformations in man ovarian theca cells in culture. Trends Endocrinol Metab. rats. Toxicol Sci. 2007;96(2):335–345 2006;17(2):65–71 60. Wilson VS, Lambright C, Ostby J, Gray LE Jr. In vitro and in 44. Abbott DH, Padmanabhan V, Dumesic DA. Contributions of vivo effects of 17beta-: a feedlot effluent contam- androgen and estrogen to fetal programming of ovarian dys- inant. Toxicol Sci. 2002;70(2):202–211 function. Reprod Biol Endocrinol. 2006;4:17 61. Shin JH, Kim HS, Moon HJ, et al. Effects of flutamide on 45. Diamanti-Kandarakis E, Alexandraki K, Piperi C, et al. In- puberty in male rats: an evaluation of the protocol for the flammatory and endothelial markers in women with polycys- assessment of pubertal development and thyroid function. J tic ovary syndrome. Eur J Clin Invest. 2006;36(10):691–697 Toxicol Environ Health A. 2002;65(5–6):433–445 46. Eriksson JG, Osmond C, Kajantie E, Forsen TJ, Barker DJ. 62. Parks LG, Lambright CS, Orlando EF, Guillette LJ Jr, Ankley Patterns of growth among children who later develop type 2 GT, Gray LE Jr. Masculinization of female mosquitofish in diabetes or its risk factors. Diabetologia. 2006;49(12): Kraft mill effluent-contaminated Fenholloway River water is 2853–2858 associated with androgen receptor agonist activity. Toxicol Sci. 47. Sanders EB, Aston CE, Ferrell RE, Witchel SF. Inter- and 2001;62(2):257–267 intrafamilial variability in premature pubarche and polycystic 63. Roman BL, Peterson RE. In utero and lactational exposure of ovary syndrome. Fertil Steril. 2002;278:473–478 the male rat to 2,3,7,8-tetrachlorodibenzo-p-dioxin impairs 48. Stoker TE, Parks LG, Gray LE, Cooper RL. Endocrine- prostate development: 1—effects on gene expression. Toxicol disrupting chemicals: prepubertal exposures and effects on Appl Pharmacol. 1998;150(2):240–253 sexual maturation and thyroid function in the male rat—a 64. Gray LE, Wolf C, Mann P, Ostby JS. In utero exposure to low focus on the EDSTAC recommendations. Endocrine Disruptor doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin alters reproduc- Screening and Testing Advisory Committee. Crit Rev Toxicol. tive development of female Long Evans hooded rat offspring. 2000;30(2):197–252 Toxicol Appl Pharmacol. 1997;146(2):237–244 49. Goldman JM, Laws SC, Balchak SK, Cooper RL, Kavlock RJ. 65. Gray LE, Ostby JS, Kelce WR. A dose-response analysis of the Endocrine-disrupting chemicals: prepubertal exposures and reproductive effects of a single gestational dose of 2,3,7,8- effects on sexual maturation and thyroid activity in the fe- tetrachlorodibenzo-p-dioxin in male Long Evans Hooded rat male rat—a focus on the EDSTAC recommendations. Crit Rev offspring. Toxicol Appl Pharmacol. 1997;146(1):11–20 Toxicol. 2000;30(2):35–196 66. Gray LE Jr, Ostby JS. In utero 2,3,7,8-tetrachlorodibenzo-p- 50. Golub MS, Hogrefe CE, Germann SL, Lasley BL, Natarajan K, dioxin (TCDD) alters reproductive morphology and function Tarantal AF. Effects of exogenous estrogenic agents on puber- in female rat offspring. Toxicol Appl Pharmacol. 1995;133(2): tal growth and reproductive system maturation in female 285–294 rhesus monkeys. Toxicol Sci. 2003;74(1):103–113 67. Gray LE Jr, Kelce WR, Monosson E, Ostby JS, Birnbaum LS. 51. Gray LE Jr, Ostby J, Ferrell J, et al. A dose-response analysis Exposure to TCDD during development permanently alters of methoxychlor-induced alterations of reproductive devel- reproductive function in male Long Evans rats and hamsters: opment and function in the rat. Fundam Appl Toxicol. 1989; reduced ejaculated and epididymal sperm numbers and sex 12(1):92–108 accessory gland weights in offspring with normal androgenic 52. Honma S, Suzuki A, Buchanan DL, Katsu Y, Watanabe H, status. Toxicol Appl Pharmacol. 1995;131(1):108–118 Iguchi T. Low dose effect of in utero exposure to bisphenol A 68. Stoker TE, Laws SC, Guidici DL, Cooper RL. The effect of and diethylstilbestrol on female mouse reproduction. Reprod atrazine on puberty in male Wistar rats: an evaluation in the Toxicol. 2002;16(2):117–122 protocol for the assessment of pubertal development and 53. Nikaido Y, Yoshizawa K, Danbara N, et al. Effects of maternal thyroid function. Toxicol Sci. 2000;58(1):50–59 exposure on development of the reproductive 69. Laws SC, Ferrell JM, Stoker TE, Schmid J, Cooper RL. The tract and mammary gland in female CD-1 mouse offspring. effects of atrazine on female Wistar rats: an evaluation of the Reprod Toxicol. 2004;18(6):803–811 protocol for assessing pubertal development and thyroid func- 54. Howdeshell KL, Hotchkiss AK. Thayer KA, Vandenbergh JG, tion. Toxicol Sci. 2000;58(2):366–376 vom Saal FS. Exposure to bisphenol A advances puberty. 70. Cooper RL, Stoker TE, Tyrey L, Goldman JM, McElroy WK. Nature. 1999;401(6755):763–764 Atrazine disrupts the hypothalamic control of pituitary- 55. Rubin BS, Murray MK, Damassa DA, King JC, Soto AM. ovarian function. Toxicol Sci. 2000;53(2):297–307 Perinatal exposure to low doses of bisphenol A affects body 71. Rubin BS, Lenkowski JR, Schaeberle CM, Vandenberg LN, weight, patterns of estrous cyclicity, and plasma LH levels. Ronsheim PM, Soto AM. Evidence of altered brain sexual Environ Health Perspect. 2001;109(7):675–680 differentiation in mice exposed perinatally to low, environ- 56. Marty MS, Crissman JW, Carney EW. Evaluation of the mentally relevant levels of bisphenol A. Endocrinology. 2006; EDSTAC female pubertal assay in CD rats using 17beta- 147(8):3681–3691

PEDIATRICS Volume 121, Supplement 3, February 2008 S205 Downloaded from www.aappublications.org/news by guest on September 29, 2021 72. Vinggaard AM, Hnida C, Breinholt V, Larsen JC. Screening of sexual maturation, and plasma hormones in pubertal girls: a selected pesticides for inhibition of CYP19 aromatase activity longitudinal study. Am J Clin Nutr. 1991;54(5):805–813 in vitro. Toxicol In Vitro. 2000;14(3):227–234 91. Maclure M. A prospective cohort study of nutrient intake and 73. Blystone CR, Furr J, Lambright CS, et al. Prochloraz inhibits age at menarche. Am J Clin Nutr. 1991;54(4):649–656 testosterone production at dosage below those that affect 92. Merzenich H, Boeing H, Wahrendorf J. Dietary fat and sports androgen-dependent organ weights or the onset of puberty in activity as determinants for age at menarche. Am J Epidemiol. the male Sprague Dawley rat. Toxicol Sci. 2007;97(1):65–74 1993;138(4):217–224 74. Laier P, Metzdorff SB, Borch J, et al. Mechanisms of action 93. Meyer F, Moisan J, Marcoux D, Bouchard C. Dietary and underlying the antiandrogenic effects of the fungicide pro- physical determinants of menarche. Epidemiology. 1990;1(5): chloraz. Toxicol Appl Pharmacol. 2006;213(2):160–171 377–381 75. Nagao T, Ohta R, Marumo H, Shindo T, Yoshimura S, Ono H. 94. Soriguer FJ, Gonzalez-Romero S, Esteva I, et al. Does the Effect of butyl benzyl phthalate in Sprague-Dawley rats after intake of nuts and seeds alter the appearance of menarche? gavage administration: a two-generation reproductive study. Acta Obstet Gynecol Scand. 1995;74(6):455–461 Reprod Toxicol. 2000;14(6):513–532 95. Blanck HM, Marcus M, Tolbert PE, et al. Age at menarche and 76. Tomonari Y, Kurata Y, David RM, Gans G, Kawasuso T, Katoh tanner stage in girls exposed in utero and postnatally to M. Effect of di(2-ethylhexyl) phthalate (DEHP) on genital polybrominated biphenyl. Epidemiology. 2000;11(6):641–647 organs from juvenile common marmosets: I—morphological 96. Blanck HM, Marcus M, Hertzberg V, et al. Determinants of and biochemical investigation in 65-week toxicity study. polybrominated biphenyl serum decay among women in the J Toxicol Environ Health. 2006;69(17):1651–1672 Michigan PBB cohort. Environ Health Perspect. 2000;108(2): 77. Garn SM, Haskell JR. Fat thickness and developmental status 147–152 in childhood and adolescence. Am J Dis Child. 1960;99: 97. Gladen BC, Ragan NB, Rogan WJ. Pubertal growth and de- 746–751 velopment and prenatal and lactational exposure to polychlo- 78. Frisch RE, Revelle R, Cook S. Components of weight at men- rinated biphenyls and dichlorodiphenyl dichloroethene. J Pe- arche and the initiation of the adolescent growth spurt in diatr. 2000;136(4):490–496 girls: estimated total water, lean body weight and fat. Hum 98. Vasiliu O, Muttineni J, Karmaus W. In utero exposure to Biol. 1973;45(3):469–483 organochlorines and age at menarche. Hum Reprod. 2004; 79. Moisan J, Meyer F, Gingras S. Diet and age at menarche. 19(7):1506–1512 Cancer Causes Control. 1990;1(2):149–154 99. Krstevska-Konstantinova M, Charlier C, Craen M, et al. Sex- 80. Adair LS, Gordon-Larsen P. Maturational timing and over- ual precocity after immigration from developing countries to weight prevalence in US adolescent girls. Am J Public Health. Belgium: evidence of previous exposure to organochlorine 2001;91(4):642–644 pesticides. Hum Reprod. 2001;16(5):1020–1026 81. He Q, Karlberg J. BMI in childhood and its association with 100. Parent A-S, Teilmann G, Juul A, Skakkebaek NE, Toppari J, height gain, timing of puberty, and final height. Pediatr Res. Bourguignon J-P. The timing of normal puberty and the age 2001;49(2):244–251 limits of sexual precocity: variations around the world, secu- 82. Freedman DS, Khan LK, Serdula MK, Dietz WH, Srinivasan SR, lar trends, and changes after migration. Endocr Rev. 2003; Berenson GS. Relation of age at menarche to race, time period, 24(5):668–693 and anthropometric dimensions: the Bogalusa Heart Study. Pe- 101. Ouyang F, Perry MJ, Venners SA, et al. Serum DDT, age at diatrics. 2002;110(4). Available at: www.pediatrics.org/cgi/ menarche, and abnormal menstrual cycle length. Occup Envi- content/full/110/4/e43 ron Med. 2005;62(12):878–884 83. Anderson SE, Dallal GE, Must A. Relative weight and race 102. Denham M, Schell LM, Deane G, et al. Relationship of lead, influence average age at menarche: results from two nation- mercury, mirex, dichlorodiphenyldichloroethylene, hexa- ally representative surveys of US girls studied 25 years apart. chlorobenzene, and polychlorinated biphenyls to timing of Pediatrics. 2003;111(4 pt 1):844–850 menarche among Akwesasne Mohawk girls. Pediatrics. 2005; 84. Davison KK, Susman EJ, Birch LL. Percent body fat at age 5 115(2). Available at: www.pediatrics.org/cgi/content/full/ predicts earlier pubertal development among girls at age 9. 115/2/e127 Pediatrics. 2003;111(4 pt 1):815–821 103. Mol NM, Sorensen N, Weihe P, et al. Spermaturia and serum 85. Herman-Giddens ME. Secondary sexual characteristics in hormone concentrations at the age of puberty in boys prena- boys: estimates from the national health and nutrition exam- tally exposed to polychlorinated biphenyls. Eur J Endocrinol. ination survey III, 1988–1994. Arch Pediatr Adolesc Med. 2001; 2002;146(3):357–363 155(9):1022–1028 104. Yang CY, Yu ML, Guo HR, et al. The endocrine and repro- 86. Lindgren G. Growth of schoolchildren with early, average and ductive function of the female Yucheng adolescents prena- late ages of peak height velocity. Ann Hum Biol. 1978;5(3): tally exposed to PCBs/PCDFs. Chemosphere. 2005;61(3): 253–267 355–360 87. Mills JL, Shiono PH, Shapiro LR, Crawford PB, Rhoads GG. 105. Hsu PC, Lai TJ, Guo NW, Lambert GH, Guo YL. Serum hor- Early growth predicts timing of puberty in boys: results of a mones in boys prenatally exposed to polychlorinated biphe- 14-year nutrition and growth study. J Pediatr. 1986;109(3): nyls and dibenzofurans. J Toxicol Environ Health. 2005; 543–547 68(17–18):1447–1456 88. Morrison JA, Barton B, Biro FM, Sprecher DL, Falkner F, 106. Den Hond E, Roels HA, Hoppenbrouwers K, et al. Sexual Obarzanek E. Sexual maturation and obesity in 9- and 10- maturation in relation to polychlorinated aromatic year-old black and white girls: the National Heart, Lung, and hydrocarbons: Sharpe and Skakkebaek’s hypothesis revisited. Blood Institute Growth and Health Study J Pediatr. 1994; Environ Health Perspect. 2002;110(8):771–776 124(6):889–895 107. Murk AJ, Leonards PEG, Bulder AS, et al. The CALUX (chem- 89. Berkey CS, Gardner JD, Frazier AL, Colditz GA. Relation of ical-activated luciferase expression) assay adapted and vali- childhood diet and body size to menarche and adolescent dated for measuring TCDD equivalents in blood plasma. growth in girls. Am J Epidemiol. 2000;1:152(5):446–452 Environ Toxicol Chem. 1997;16(8):1583–1589 90. de Ridder CM, Thijssen JH, Van’t Veer P, et al. Dietary habits, 108. Warner M, Samuels S, Mocarelli P, et al. Serum dioxin con-

S206 BUCK LOUIS et al Downloaded from www.aappublications.org/news by guest on September 29, 2021 centrations and age at menarche. Epidemiology. 2004;15(4): 116. Kelce WR, Stone CR, Laws SC, Gray LE, Kemppainen JA, S116–S117 Wilson EM. Persistent DDT metabolite p,pЈ-DDE is a potent 109. Colon I, Caro D, Bourdony CJ, Rosario O. Identification of androgen receptor antagonist. Nature. 1995;375(6532): phthalate esters in the serum of young Puerto Rican girls with 581–585 premature breast development. Environ Health Perspect. 2000; 117. Gray LE Jr. Xenoendocrine disrupters: laboratory studies on 108(9):895–900 male reproductive effects. Toxicol Lett. 1998;102–103:331–335 110. NTP-CERHR. Monograph on the Potential Human Reproduction 118. Ashby J, Lefevre PA. The peripubertal male rat assay as an and Developmental Effects of Di (2-Ethylhexyl) Phthalate (DEHP). alternative to the Hershberger castrated male rat assay for the Research Triangle Park, NC: National Toxicology Program, detection of anti-androgens, oestrogens and metabolic mod- Center for the Evaluation of Risks to Human Reproduction; ulators. J Appl Toxicol. 2000;20(1):35–47 2006. NIH publication 06-4476 119. Barker DJP. Fetal and Infant Origins of Adult Disease. London, 111. Saiyed H, Dewan A, Bhatnagar V, et al. Effect of endosulfan England: BMJ Publication; 1992 on male reproductive development. Environ Health Perspect. 120. Barker DJP. Adult consequences of fetal growth restriction. 2003;111(16):1958–1962 Clin Obstet Gynecol. 2006;49(2):270–283 112. Selevan SG, Rice DC, Hogan KA, Euling SY, Pfahles-Hutchens 121. Buck GM, Lynch CD, Stanford JB, et al. Prospective preg- A, Bethel J. Blood lead concentration and delayed puberty in nancy study designs for assessing reproductive and develop- girls. N Engl J Med. 2003;348(16):1527–1536 mental toxicants. Environ Health Perspect. 2004;112(1):79–86 113. Wu T, Buck GM, Mendola P. Blood lead levels and sexual 122. Chapin RE, Robbins WA, Schieve LA, Sweeney AM, Tabacova maturation in U.S. girls: the Third National Health and Nu- SA, Tomashek KM. Off to a good start: the influence of pre- trition Examination Survey, 1988–1994. Environ Health Per- and periconceptional exposures, parental , and nutri- spect. 2003;111(5):737–741 tion on children’s health. Environ Health Perspect. 2004;112(1): 114. Dearth RK, Hiney JK, Srivastava V, Burdick SB, Bratton GR, 69–78 Dees WL. Effects of lead (Pb) exposure during gestation and 123. Louis GB, Dukic VM, Heagerty PJ, et al. Statistical issues in lactation on female pubertal development in the rat. Reprod modeling pregnancy outcome data. Stat Methods Med Res. Toxicol. 2002;16(4):343–352 2006;15(2):103–126 115. Grant LD, Kimmel CA, West GL, Martinez-Vargas CM, 124. Mun˜oz-de-Toro M, Markey CM, Wadia PR, Luque EH, Rubin Howard JL. Chronic low-level lead toxicity in the rat: II— BS, Sonnenschein C, Soto AM. Perinatal exposure to bisphe- effects on postnatal physical and behavioral development. nol-A alters peripubertal mammary gland development in Toxicol Appl Pharmacol. 1980;56(1):42–58 mice. Endocrinology. 2005;146(9):4138–4147

PEDIATRICS Volume 121, Supplement 3, February 2008 S207 Downloaded from www.aappublications.org/news by guest on September 29, 2021 Environmental Factors and Puberty Timing: Expert Panel Research Needs Germaine M. Buck Louis, L. Earl Gray, Jr, Michele Marcus, Sergio R. Ojeda, Ora H. Pescovitz, Selma Feldman Witchel, Wolfgang Sippell, David H. Abbott, Ana Soto, Rochelle W. Tyl, Jean-Pierre Bourguignon, Niels E. Skakkebaek, Shanna H. Swan, Mari S. Golub, Martin Wabitsch, Jorma Toppari and Susan Y. Euling Pediatrics 2008;121;S192 DOI: 10.1542/peds.1813E

Updated Information & including high resolution figures, can be found at: Services http://pediatrics.aappublications.org/content/121/Supplement_3/S192 References This article cites 112 articles, 0 of which you can access for free at: http://pediatrics.aappublications.org/content/121/Supplement_3/S192 #BIBL Subspecialty Collections This article, along with others on similar topics, appears in the following collection(s): Endocrinology http://www.aappublications.org/cgi/collection/endocrinology_sub Puberty http://www.aappublications.org/cgi/collection/puberty_sub Environmental Health http://www.aappublications.org/cgi/collection/environmental_health_ sub Permissions & Licensing Information about reproducing this article in parts (figures, tables) or in its entirety can be found online at: http://www.aappublications.org/site/misc/Permissions.xhtml Reprints Information about ordering reprints can be found online: http://www.aappublications.org/site/misc/reprints.xhtml

Downloaded from www.aappublications.org/news by guest on September 29, 2021 Environmental Factors and Puberty Timing: Expert Panel Research Needs Germaine M. Buck Louis, L. Earl Gray, Jr, Michele Marcus, Sergio R. Ojeda, Ora H. Pescovitz, Selma Feldman Witchel, Wolfgang Sippell, David H. Abbott, Ana Soto, Rochelle W. Tyl, Jean-Pierre Bourguignon, Niels E. Skakkebaek, Shanna H. Swan, Mari S. Golub, Martin Wabitsch, Jorma Toppari and Susan Y. Euling Pediatrics 2008;121;S192 DOI: 10.1542/peds.1813E

The online version of this article, along with updated information and services, is located on the World Wide Web at: http://pediatrics.aappublications.org/content/121/Supplement_3/S192

Pediatrics is the official journal of the American Academy of Pediatrics. A monthly publication, it has been published continuously since 1948. Pediatrics is owned, published, and trademarked by the American Academy of Pediatrics, 345 Park Avenue, Itasca, Illinois, 60143. Copyright © 2008 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 1073-0397.

Downloaded from www.aappublications.org/news by guest on September 29, 2021