Journal of Exposure Science and Environmental Epidemiology (2007) 17, 191–195 r 2007 Nature Publishing Group All rights reserved 1559-0631/07/$30.00

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Maternal contamination with PCBs and reproductive outcomes in an Australian population

NARGES KHANJANI AND MALCOLM ROSS SIM

Monash Centre for Occupational & Environmental Health, Department of Epidemiology & Preventive Medicine (Monash University), The Alfred Hospital, Melbourne, VIC, Australia

Polychlorinated biphenyls used previously in industry are widespread environmental contaminants under scrutiny for their possible reproductive effects in humans. In this study, 200 breast milk samples from eligible Victorian mothers were used for measuring maternal contamination and their possible effect on the offspring was investigated. No significant association was found between maternal PCB contamination and low birth weight, small for gestational age and previous miscarriage or stillbirth. The elevated odd ratios of prematurity, increased with increase in contamination level but were nonsignificant. Higher PCB contamination was not in favor of any gender in the offspring. Our results suggest that chronic, low contamination with PCBs does not pose a reproduction threat in humans. Journal of Exposure Science and Environmental Epidemiology (2007) 17, 191–195. doi:10.1038/sj.jes.7500495; published online 14 June 2006

Keywords: polychlorinated biphenyls, PCBs, reproduction, birth weight, prematurity, sex ratio.

Introduction caused developmental toxic effects in the litter of experi- mental animals, such as reduced birth weight, abortion or Polychlorinated Biphenyls (PCBs) a group of polycyclic neonatal mortality in monkeys, rats and sea lions (DeLong chlorinated hydrocarbons, are widespread environmental et al., 1973; Fein et al., 1984; Patandin et al., 1998). contaminants (Fein et al., 1984; Patandin et al., 1998), likely The widespread contamination with PCBs and its effects to possess oncogenic and teratogenic properties (Lackmann on animals raises the question of the effect of these chemicals et al., 1996). PCBs consist of mixtures of 210 different on human health. In human studies, maternal contamination isomers with various degrees of chlorination. The with PCBs has been reported to be associated with low birth chemical and thermal stability of PCBs resulted in their wide weight (Fein et al., 1984; Patandin et al., 1998; Rylander use in industry in equipment such as capacitors (Taylor et al., et al., 1998), smaller head circumference (Fein et al., 1984), 1989). shorter height in males (Dewailly et al., 1993) and shorter PCBs are no longer manufactured or used in the United gestational length (Fein et al., 1984; Taylor et al., 1989), States or the European Economic Community. Their although results have not been consistent. Our aim was to importation into Australia was prohibited in 1976 but their investigate a range of adverse reproductive outcomes in industrial use continued after this date (Sim, 1993) and women, using breast milk PCB concentration as a measure of human exposure to PCBs is still continuing mainly through body burden. the food chain (Fein et al., 1984; Patandin et al., 1998). PCBs are lipophilic and resistant to either chemical or biological degradation and accumulate in the fat tissue of Methods animals and humans (Patandin et al., 1998). The human fetus can be exposed to PCBs through placental transport Study Participants and later during breast-feeding (Rogan et al., 1988; For this study, we used exposure and reproductive outcome Lackmann et al., 1996). Prenatal exposure to PCBs has data collected as part of a previous breast milk study conducted in the early 1990s. The objective of the previous 1. Address all correspondence to: Dr. Narges Khanjani, Monash Centre study was to measure the contamination level of organo- for Occupational & Environmental Health, Department of Epidemiology chlorines in the Victorian population by using a non-invasive & Preventive Medicine, Monash University, Alfred Hospital, Commercial technique. The participants were 200 Victorian mothers who Road, Melbourne, VIC 3004, Australia. Tel.: þ 61 3 9903 0045. Fax: were a random sample recruited from Maternal and Child þ 61 3 9903 0576. E-mail: [email protected] Received 9 December 2005; accepted 3 April 2006; published online Health Centres, throughout Victoria (Sim et al., 1998). 14 June 2006 Victoria is a state in the south east of Australia. It had a Khanjani and Sim PCBsandhumanreproduction female population of 2,147,409 at the 1991 census. It et al., 2003). Thus, in order to be able to correct for includes a mixture of cities and rural areas. The biggest city is prematurity, the ‘‘small for gestational age’’ outcome variable Melbourne. There is a lot of primary industry in the rural was also used. This variable was created by comparing the area. birth weight of each baby with the appropriated weight for The study protocol was reviewed and approved in writing that sex and gestational age. For this purpose, we used data by the Monash University Standing Committee on Ethics in about the appropriate weight for gestational age in boys and Research involving Humans, prior to the commencement of girls from a Canadian study (Kramer et al., 2001) as we did the study. All participants were provided with an information not have Australian data. If the birth weight was less than the pamphlet prior to being asked to participate in the study. 10th percentile, it was classified as small for gestational age. Each participant was requested to sign a consent form Mothers were classified in the ‘‘previous miscarriage or still witnessed by the Maternal and Child Health nurse upon birth’’ group if they had at least one miscarriage or still birth agreeing to take part in the study. prior to the birth of their recent first live child. Prematurity To be eligible to participate, women had to be primiparous, was defined as any baby born more than 3 weeks (21 days) fully breast feeding, have a singleton birth and be between 6 before the expected time of delivery or a baby born before and 12 weeks postpartum (Sim and McNeil, 1992). completion of the 37th week of gestation (40 weeks is the Each participant collected a 75 cc sample of her breast milk normal expected time of pregnancy). in a glass jar and completed a self administered questionnaire. Mother’s weight and height was measured by a research Statistical Analysis nurse. Details of the baby at the time of birth were taken Logistic regression was used to calculate the crude and from health files. adjusted odds ratios with 95% confidence intervals for the The chemical analysis of the fat proportion of the breast categorical outcomes (SGA, low birth weight, gender, milk sample was carried out by gas chromatography at the preterm birth and previous miscarriage or still birth). State Chemistry Laboratory in Victoria. The amount of total Subjects were divided into three exposure groups; non- PCBs in breast milk fat was measured in the samples. The detectable, low contamination and high contamination. In detection limit was 0.01 mg/kg breast milk fat. The the detectable samples the lower 50% was defined as low laboratory reported the results in sum of PCBs and not contamination and the higher 50% was defined as high individual congeners. Others chemicals such as DDT, b- contamination. Linear regression was performed for head Hexachlororcyclohexane, Hexachlorobenzene and Cyclo- circumference and the subjects were divided into the same dienes had also been measured and have been published three exposure categories. Mother’s age, weight, education, separately (Khanjani and Sim, 2006a, b). smoking and drinking during pregnancy were adjusted for in Organochlorines are lipophilic compounds that the analysis. partition into fat; thus the fat content of breast milk is a major determinant of the chemical level in whole milk. The concentration of fat may vary throughout the lactation period. To exclude this variation results should Results be reported in terms of milk fat concentration rather than concentration in whole milk (Sim and McNeil, The mean age of the 200 mothers who participated was 28.2 1992). The measurements are carried out in the whole fat years, and 51.5% of the babies were male. The birth weight content of the milk, without differentiating for triglyceride or of the babies ranged from a minimum of 2070 to a maximum cholesterol. of 4870 g, with a mean of 3366 g. The mean head The amount of PCBs found in maternal milk is an index of circumference was 34 cm, with a range (minimum and maternal ‘‘body burden’’ and thus of the exposure of the maximum) from 29 to 38 cm. Total PCBs were detected in embryo and fetus. This method of exposure measurement has 58.5% of the breast milk samples. Amounts less than been used in several previous studies (Dewailly et al., 1993; 0.01 mg/kg lipid were not detectable. The descriptive Sauer et al., 1994; Schade and Heinzow, 1998). statistics of PCB contamination has been summarized in Table 1 . Outcome Measures The categorical variables and the results of logistic The outcome variables were low birth weight, small for regression have been listed in Table 2. We were not able to gestational age (SGA), previous miscarriage or still birth, find any significant association or trend between SGA preterm birth, head circumference and ratio of female (n ¼ 32), miscarriage or stillbirth before the recent live birth offspring. (n ¼ 22) or low birth weight (n ¼ 5) and contamination with Low birth weight was defined as any baby with a birth PCBs. Prematurity and contamination with PCBs did not weight less than 2500 g. However, birth weight and have significantly elevated odds ratios, but they increased gestational age are usually positively correlated (Baibergenova from the second to the third level of contamination with a

192 Journal of Exposure Science and Environmental Epidemiology (2007) 17(2) PCBsandhumanreproduction Khanjani and Sim non-significant trend. No association between PCB level and Discussion gender was detected. Head circumference data were available for only 153 Our study did not reveal an association between low levels of babies, with 65 in the non-detectable, 44 in the low maternal PCB contamination (less than 0.22 mg/kg breast contamination (r0.05 mg/kg) and 44 in the high contam- milk fat; also see Table 1) and reproductive outcomes; such as ination (40.05 mg/kg) group. The mean head circumference small for gestational age, prematurity, low birth weight, in the three groups was, respectively, 34.24, 34.40, 34.44 cm; previous miscarriage or stillbirth and sex ratio. Our measures with no statistically significant differences between the were less than some similar previous studies using breast milk groups. for PCB contamination measurement (Rogan et al., 1986; We repeated the whole analysis with PCB contamination Schade and Heinzow, 1998; Vartiainen et al., 1998). as a continuous instead of categorical variable. However, we Similar to our study, several previous studies have found still did not get a significant result for any outcome. no significant association between the concentration of PCBs in milk samples and birth weight of primiparas (Rogan et al., 1986; Vartiainen et al., 1998) or head circumference (Rogan et al., 1986). Several studies which have measured fetal Ta bl e 1 . Descriptive statistics of PCB contamination measured in milk exposure to PCBs by maternal fish intake from contaminated samples (unit: mg/kg breast milk fat). watersdidnotfindassociationsbetweenhighintakeofPCBs in the mother and miscarriage (Axmon et al., 2000), stillbirth Number of detected samples 58.5% (Axmon et al., 2000; Rylander et al., 2000), spontaneous Mean 0.038 SD 0.042 fetal death (Mendola et al., 1995) or congenital malforma- Minimum o0.01 tions (Rylander et al., 2000). Although, some studies 25th percentile o0.01 reported smaller birth weight (Fein et al., 1984; Rylander Median 0.03 et al., 2000), smaller head circumference (Fein et al., 1984; 75th percentile 0.06 Rylander et al., 2000) and shorter gestational period (Fein Maximum 0.22 et al., 1984), these results should be interpreted cautiously

Ta bl e 2 . Crude and adjusted odds ratios for the association between premature birth, low birth weight, small for gestation age, miscarriage or stillbirth, female births and total PCB contamination.

Number of samples Crude OR Adjusteda OR Test of trend P-value

Prematurity Non-detectable 3/83 r0.05b 3/55 1.53 (0.30, 7.91) 1.41 (0.25, 7.96) 0.43 40.05 4/62 1.84 (0.40, 8.53) 2.30 (0.40, 13.34)

Low birth weight Non-detectable 4/83 0.17 (0, 1.16)c Numbers too low Numbers too low Detectable 1/117

Small for gestation age Non-detectable 15/83 r0.05 9/55 0.89 (0.36, 2.20) 0.87 (0.34, 2.22) 0.41 40.05 8/62 0.67 (0.27, 1.70) 0.61 (0.22, 1.66)

Miscarriage or stillbirth Non-detectable 11/83 r0.05 4/55 0.51 (0.15, 1.70) 0.60 (0.17, 2.14) 0.65 40.05 7/62 0.83 (0.30, 2.29) 1.07 (0.34, 3.35)

Female births Non-detectable 41/83 r0.05 28/55 1.06 (0.54, 2.10) 0.98 (0.48, 2.02) 0.64 40.05 28/62 0.84 (0.44, 1.63) 0.75 (0.36, 1.55) aAdjusted for mother’s age, weight, education and smoking and drinking during pregnancy. bThe unit of measurement is mg/kg fat in breast milk. cOdds ratio calculated by Cornfield exact test.

Journal of Exposure Science and Environmental Epidemiology (2007) 17(2) 193 Khanjani and Sim PCBsandhumanreproduction because of the possible contamination of fish with other In this study, we only enrolled primiparous women. Thus, chemicals, such as mercury. we lost women with a history of miscarriages and stillbirths Studies have reported high paternal PCB concentrations to who eventually did not give birth to a live baby. If, in fact, affect sex ratio (Karmaus et al., 2002), but our study and these women were experiencing these outcomes because of others (Schade and Heinzow, 1998) found no effect of their higher contamination, we may be underestimating the maternal PCB intake on the sex ratio of the offspring. effects of these chemicals. Massive unintentional contamination with PCBs has been We were not able to adjust for the Maternal and Child reported from two separate accidents. The first was in 1968 in Health Centres because we collected data from 189 centres. west Japan, where PCB induced fetopathy was found in However, the data was collected in a standardized manner babies born to mothers poisoned by contaminated rice oil and the nurses followed a strict protocol. (Funatsu et al., 1972), although there was no excess of births The measure of ‘‘miscarriage or stillbirth’’ was based on of girls over boys (Yoshimura et al., 2001). In the second the mother’s recall. Although it seems unlikely for a woman outbreak in Taiwan in 1979, maternal contamination by not to remember a stillbirth or late miscarriage; an early cooking oil lead to lower birth weight, hyperpigmentation, miscarriage may not have been reported. conjuctivitis, nail changes, natal teeth at birth and consistent We used Canadian and not Australian data for determin- developmental delay in the exposed offspring (Rogan et al., ing the appropriate weight for gestational age. However, the 1988), although again in maternal contamination the sex Canadian data was the best that suited our study and could ratio was not affected (Rogan et al., 1999). These findings represent the Australian population. suggest that reproductive effects can occur from massive Another potential limitation in this study is that we did not acute PCB exposure. control for other organochlorine compounds that may have Occupational exposure with PCBs has been associated an effect on reproductive outcomes. However, the data about with a decrease in both birth weight and gestational the other contaminants (DDT, b-Hexachlororcyclohexane, age in babies born to women working in areas of high Hexachlorobenzene and Cyclodienes) did not show a PCB exposure (Taylor et al., 1989). Some evidence significant effect for any of them (Khanjani and Sim, about mother’s residence near hazardous waste sites increas- 2006a, b). ing the risk of having low birth weight births has been In conclusion, our study suggests that low levels of reported (Baibergenova et al., 2003), although in these maternal PCB contamination do not pose a threat to the studies there is the possibility of exposure to other chemicals human fetus and these findings should reduce anxiety about or risk factors. adverse reproductive effects from chronic low-level PCB In comparison to the other studies, our study had some contamination. strengths. We used human biological samples for measuring exposure, which is a much stronger method than indirect measures of exposure, such as fish consumption. Also, in the Acknowledgements analysis, we were able to adjust for several potential confounding factors such as mother’s age and weight; but N Khanjani acknowledges the Iranian Ministry of Health and not other factors such as race and prenatal nutrition. Medical Education which has sponsored her PhD studies. Our study also had some limitations, such as a low number of subjects leading to low precision of our results. Also, as in many previous studies the sum value of PCBs has been References reported. Although, PCBs have three main subgroups with Axmon A., Rylander L., Stromberg U., and Hagmar L. Miscarriages and different hormonal characteristics (Wolff and Toniolo, 1995), stillbirths in women with a high intake of fish contaminated with persistent we were not able to focus on individual PCBs or PCB organochlorine compounds. IntArchOccupEnvironHealth2000: 73: subgroups to determine their individual effects, which may 204–208. Baibergenova A., Kudyakov R., Zdeb M., and Carpenter D.O. 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