Association between serum concentrations of hexachlorobenzene and polychlorobiphenyls with thyroid hormone and liver enzymes in a sample of the general population

Objectives-Hexachlorobenzene (HCB) is a highly lipophilic. organochlorine c ompound of widespread environmental. occurrence, that accumulates in the bi ological system. Pt affects the porphyrine metabolism, thyroid hormones, an d the liver function in animals. Although HCB is one of the most common org anochlorine compound in humans, little investigation on its health effects has been done. Polychlorobiphenyls (PCBs) are also widespread toxic environ mental contaminants. The aim of the present study was to investigate the as sociation of serum HCB and PGB concentrations with thyroid hormone status a nd liver enzymes in human. Methods-Thyroid stimulating hormone (TSH), total and free thyroxine (T4), a spartate aminotransferase (AST), alanine aminotransferase (AET) and gamma - glutamyltransferase (GGT) were measured as biological markers of thyroid an d liver function in a rural population sample older than 14 years (n=192, e xcept for TSH with n=608) highly exposed to HCB. Serum concentrations of HC B were measured by gas chromatography coupled to electron capture detection . Results-After adjustment for confounding variables, there wars a significan t negative association between serum HCB concentrations and total T4 (a dec rease of 0.32 mug/dl per each unit, 1n ng/ml, of increase of HCB) and a pos itive association with GGT (a relative increase of 10 % per each In unit of increase of HCB), although most subjects (92%) were within the normal rang e for both T4 and GGT, These associations were not modified after adjustmen t for total lipid content or for other organochlorine compounds. The associ ation of T4 and GGT with PCB was smaller although significant. No associati on was found with the other biochemical markers. Conclusions-These results suggest that the internal dose of HCB of this pop ulation may reflect a subtle metabolic effect on thyroid function and an en zymatic induction activity. Further studies are needed to evaluate the heal th impact of these effects in more susceptible populations, such as infants .