Academic journal article Environmental Health Perspectives

Exposure to Hydroxylated Polychlorinated Biphenyls (OH-PCBs) in the Prenatal Period and Subsequent Neurodevelopment in Eastern Slovakia

Academic journal article Environmental Health Perspectives

Exposure to Hydroxylated Polychlorinated Biphenyls (OH-PCBs) in the Prenatal Period and Subsequent Neurodevelopment in Eastern Slovakia

Article excerpt

BACKGROUND: Hydroxylated polychlorinated biphenyls (OH-PCBs), unlike PCBs, are in general readily excreted yet are still detected in humans and animals. Active transport of OH-PCBs across the placenta and hydroxylation of PCBs by the fetus suggest the potential for greater impact on the fetus compared with the parent PCB compounds, but little is known about their health effects, particularly in humans.

OBJECTIVES: The objective of this study was to evaluate the associations between prenatal OH-PCB exposure and neurodevelopment in children at 16 months of age in eastern Slovakia.

METHODS: A birth cohort (n = 1,134) was enrolled during 2002-2004. We analyzed six OH-PCB metabolites (4-OH-CB-107, 3-OH-CB-153, 4-OH-CB-146, 3-OH-CB-138, 4-OH-CB-187, and 4'-OH-CB-172) in a subset of the cohort. The Bayley Scales of Infant Development were administered to the children at the 16-month follow-up visit. We developed multiple linear regression models predicting standardized scores for the Mental Development Index (MDI) and Psychomotor Development Index (PDI) from maternal (n = 147) and cord (n = 80) serum OH-PCB concentrations, adjusting for sex of child, district, HOME (Home Observation for Measurement of the Environment) score, and maternal score on Raven's Progressive Matrices.

RESULTS: Cord 4-OH-CB-107 was significantly associated with lower MDI ([beta] = -2.27; p = 0.01) and PDI ([beta] = -4.50; p = 0.004). Also, maternal 4-OH-CB-107 was significantly associated with lower MDI ([beta] = -1.76; p = 0.03) but not PDI. No other OH-PCB metabolites were associated with decreased PDI or MDI.

CONCLUSIONS: Our findings showed a significant association of 4-OH-CB-107 with decreased MDI, which can possibly be mediated by endocrine disruption, altered neurotransmitter functions, or reduced thyroid hormone concentrations in brain.

KEY WORDS: Bayley Scales of Infant Development, hydroxylated PCBs, Slovakia. Environ Health Perspect 117:1600-1606 (2009). doi:10.1289/ehp.0900611 available via http://dx.doi.org/ [Online 20 May 2009]

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Adverse effects of polychlorinated biphenyls (PCBs) on neurodevelopment have been well documented by growing evidence from in vivo and in vitro studies (Bemis and Seegal 2004; Carpenter et al. 2002; Ozcan et al. 2004; Seegal et al. 2005; Tan et al. 2004) and from epidemiologic studies (Darvill et al. 2000; Gladen et al. 1988; Jacobson and Jacobson 1996; Patandin et al. 1999; Rogan and Gladen 1991; Walkowiak et al. 2001). Although the mechanisms for this effect are still not well understood, one hypothesis is disruption of thyroid hormone homeostasis (Porterfield and Hendry 1998).

Over the past decade, there has been increasing research on hydroxylated PCBs (OH-PCBs), which are formed by cytochrome P450-mediated oxidation from PCBs (Letcher et al. 2000). Unlike PCBs, which are relatively stable and highly lipophilic, OH-PCBs are readily excreted. Nevertheless, several studies have observed detectable levels of OH-PCBs in both animals and humans (Bergman et al. 1994; Hovander et al. 2002; Park et al. 2007; Soechitram et al. 2004). Soechitram et al. (2004) found that OH-PCB levels in umbilical cord plasma were approximately 50% of maternal concentrations, whereas the parent PCBs concentrations in cord plasma were around 30% of maternal levels. The authors suggested that this difference may be explained by active transport of OH-PCBs across the placenta and hydroxylation of PCBs by the fetus itself, whereas transplacental transfer is the only source of fetal PCBs. In our study population (Park et al. 2007), the median cord-to-maternal ratios were 0.75 for the sum of OH-PCBs and 0.18 for the sum of PCBs from wet-weight-based concentrations. This result supports both transport across the placenta of these metabolites and the potential for greater impact on the fetus, compared with the parent PCB compounds.

Although in vitro and in vivo studies have shown adverse effects of OH-PCBs on thyroid or sex hormone homeostasis (Meerts et al. …

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