PCB congeners and pesticides and female fecundity, New York State Angler Prospective Pregnancy Study

Abstract

Consumption of PCB-contaminated sport fish from Lake Ontario has been reported to be associated with diminished female fecundity. To identify Polychlorinated biphenyl (PCB) congeners and other pesticides that might be associated with reduced fecundity, we followed 102 women aged 20–34 years attempting pregnancy who completed daily diaries for 12 at risk menstrual cycles. Fecundity referred to time-to-pregnancy (TTP) or the number of at risk menstrual cycles required for pregnancy. Blood specimens were obtained for 88 (86%) women and were analyzed using gas chromatography and electron capture for 66 PCB congeners and seven pesticides. Laboratory values were recovery, background and fat corrected prior to natural log transformation. Using stepwise discriminant analysis, congeners IUPAC #205 and #206 and hexaclorobenzene were significantly and positively associated with increasing TTP when women were categorized as becoming pregnant in the first or first three at risk menstrual cycles, respectively. Congeners #205 and #206 are reported to have (anti) estrogenic structural activity.

Introduction

Polychlorinated biphenyls (PCBs) are regarded by many investigators as being capable of altering hormonal pathways leading to disturbances in reproductive and developmental function. These chemicals have been broadly referred to as endocrine disrupting chemicals (EDCs) or hormonally active agents in the environment (National Research Council, 2000). Although a plethora of adverse outcomes have been reported in animal and wildlife species following exposure to EDCs, ranging from altered sexual behavior to malformations, limited study of human reproductive health has been conducted. We are aware of only seven studies that have addressed so-called EDCs and human fecundity or biologic capacity for reproduction including menstruation or fertility defined as live births (Rachoutin and Olsen, 1983, de Cock et al., 1994, Curtis et al., 1999, Thonneau et al., 1999, Axom et al., 2000, Buck et al., 2000, Yu et al., 2000). The later three studies have focused on PCBs, specifically.

We previously reported that consumption of PCB contaminated fish from Lake Ontario by women of reproductive age was associated with a reduction in fecundability (Buck et al., 2000). Specifically, women who consumed fish for 3–6 years or who reported recent consumption of at least one monthly fish meal were approximately 25% less likely to become pregnant per cycle than women who did not consume fish. Sport fish in Lake Ontario are reported to be the most highly contaminated of all Great Lakes fish, and contain levels of dioxin and mirex that exceed the Food and Drug Administration's tolerance limits (Clark et al., 1984, Flint and Vena, 1991). Another recent study of time-to-pregnancy (TTP) among wives of fisherman from the east and west coasts of Sweden reported an increase in TTP only among women who were heavy cigarette smokers and who lived on the east coast (Axom et al., 2000). Specifically, the success rate ratio (i.e. number of pregnancies per month) was significantly reduced for exposed women (SuR=0.68; 95% confidence intervals 0.51–0.91) in comparison to unexposed women. Neither study had individual exposure data on PCBs. Mendola et al. (1997) reported a significant reduction in menstrual cycle length associated with consumption of PCB contaminated sport fish from Lake Ontario raising concern about the effect(s) of environmental aquatic contaminants on female fecundity. Abnormal menstrual bleeding was reported to be higher among women exposed to PCBs in Yucheng in comparison to control women (Yu et al., 2000). These early data underscore the need to measure serum concentrations of PCBs and to identify individual congeners which might be associated with reduced fecundity in women. This is in keeping with the structural differences in PCB congeners and their potential to exert different effects on human health endpoints. We attempted to identify PCB congeners and selected pesticides that might be subtle markers of threats to human reproduction as evidence by their association with a longer TTP. Our intent was not to model fecundability, per se.