In utero exposure to polychlorinated biphenyls (PCBs) and age at menarche in a contemporary cohort of British girls Open Access

Freiman, Heather Christine (2011)

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Polychlorinated biphenyls (PCBs) are persistent organic chemicals widely used as coolants in electronics until the 1980s. Despite being banned for decades, PCBs are frequently detected in human serum and have demonstrated endocrine modulating effects. The authors conducted a nested case-control study, with data from the Avon Longitudinal Study of Parents and Children (ALSPAC) in the United Kingdom, to examine the association between in utero PCB exposure and age at menarche. Cases were chosen from girls reporting menarche before 11.5 years (n=218) and controls were a random sample of the remaining girls not reporting menarche before 11.5 years (n=230). Maternal serum samples were collected during pregnancy (1991-1992); these samples were analyzed for PCB congeners using solid phase extraction followed by gas chromatography isotope dilution high resolution mass spectrometry. Multivariate logistic regression was used to assess the association between maternal serum PCB concentration during pregnancy (proxy for in utero PCB exposure) and odds of earlier age at menarche in daughters.

Most samples had detectable levels of all PCB congeners, and the most prevalent congeners were PCBs 118, 138-158, 153, 170, and 180 (total median serum concentration 184.10 ng/g lipid). The total PCB concentration varied slightly, but not significantly, with maternal and child characteristics. For analyses, PCB congeners were grouped by proposed endocrine action and homolog classification in addition to total PCB level. Logistic regression models adjusted for maternal age at menarche, pre-pregnancy BMI, age at delivery, and parity. All PCB groups, analyzed as continuous variables, were associated with decreased odds of earlier age at menarche (e.g. adjusted odds ratio [aOR] Total PCBs = 0.68, 95% confidence interval 0.34, 1.34). When the PCB groups were analyzed as categorical variables, the association with earlier age at menarche was less consistent. All 95%confidence intervals for the ORs included the null value of 1.0.

Although most ALSPAC study participants had detectable PCB levels, PCB exposure was not significantly associated with age at menarche in offspring; these findings suggest that in utero PCB exposure is not associated with earlier age at menarche.

Table of Contents

Literature Review/Background...1
Materials and Methods...10
Tables and Figures...31

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