Possible Effects of Polychlorinated Biphenyls and Organochlorinated Pesticides on the Thyroid after Long-term Exposure to Heavy Environmental Pollution

Abstract

The purpose of this work was to study the effects of high environmental exposure to polychlorinated biphenyls (PCBs) and other organochlorines on the thyroid. Thyroid volume, hypoechogenicity and nodules (by ultrasound), presence of antithyroid peroxidase (anti-TPO) antibodies, and abnormal thyroid-stimulating hormone (TSH) levels in serum (by radioimmunoassay) were examined in 101 adults from the PCB-polluted area in 360 controls. Serum levels of PCBs, hexachlorobenzene, gamma-hexachlorocyclohexane (HCH), p,p'-DDT(1,1,1-trichloro-2,2'-bis(p-chlorophenyl)ethane), and p,p'-DDE(1,1-dichloro-2,2'-bis(p-chlorophenyl)ethene) were measured by high-resolution gas chromatography. Very high levels of PCBs were found in the polluted area (7300 +/- 871 ng/g lipids) compared with controls (2045 +/- 147 ng/g). Positive correlations (P < 0.001) were found between the levels of all organochlorines and their total except for hexachlorocyclohexane (HCH). In the polluted area, the highest thyroid volumes (18.7 +/- 2.32 mL; mean +/- SE) were clustered among 23 subjects (17 males and six females) with PCB levels above 10,000 ng/g (range 10,000-58,667 ng/g). In the remaining 438 subjects the thyroid volume was 14.2 +/- 0.29 mL. These data suggest that there might be a threshold serum PCB level of approximately 10,000 ng/g that may influence the thyroid volume. A two-way ANOVA showed that all thyroid volumes in the polluted area were significantly higher (P < 0.001) than in the control area. In males from the polluted area, the frequencies of thyroid hypoechogenicity, thyroid nodules, positive anti-TPO, and abnormal TSH level were higher than in males from the control area, whereas such differences were not observed in females. Increased thyroid volume and indicators of potential thyroid dysfunction were associated with long-term environmental exposure to PCBs. These effects on the thyroid were confined to subjects with PCB levels above 10,000 ng/g of lipid (thyroid volume) and to males from the polluted area (thyroid hypoechogenicity, thyroid nodules, positive anti-TPO, and abnormal TSH).

Lipid Adjustment in the Analysis of Environmental Contaminants and Human Health Risks

“…Investigators typically have insufficient biologic information to specify the correct analytic model, often resulting in analytic strategies based on unverified assumptions. For example, research indicates a possible causal effect of PCBs on serum lipid levels (Hennig et al 2005; Langer et al 2003). Additionally, lipid levels have been suggested to affect breast cancer risk (Atalay et al 2004), but their impact on other health end points has received limited attention.…”

PAHs and PCBs accumulated by SPMD-based virtual organisms and feral fish in Three Gorges Reservoir, China

“…The nondioxin-like (ndl) PCBs group includes the remaining congeners (US EPA, 2003). These compounds have been demonstrated to cause toxic effects on human being and animal reproduction, development and immunological function, endocrine and nervous systems as well as carcinogenetic/mutagenic potential (Suchan et al, 2004;Langer et al, 2003;Lee et al, 2006;Ha et al, 2007). Although banned in most industrial countries for several decades, PCBs are still widely spread in the marine and terrestrial biota and biomagnify throughout food chain (Covaci et al, 2002;Letcher et al, 2010).…”

Dietary intake of organochlorine pesticides through fish from bulgarian black sea coast

“…DDT is still used for vector control against malaria (6). These very persistent compounds _______________________________ have the potential to affect the physiological functions of wildlife (7). Marine organisms such as fish and marine filter feeders, can also act as bioconcentrators, creating levels of DDT in their tissues above ambient environmental concentrations (3).…”