PRELIMINARY OBSERVATIONS ON ENDOCRINE DISRUPTING EFFECTS OF POLYCHLORINATED BIPHENYLS (PCBS) IN THE POPULATION EXPOSED TO HEAVY ENVIRONMENTAL POLLUTION

Abstract

A chemical factory, Chemko, at Strazske, East Slovakia, produced 21,500 tons PCBs during 1959–1984. Large amounts of PCBs contaminated the environment due to poor technological and preventive measures. Up to 20-times higher PCB levels were found in ambient air samples close to the Chemko landfill site and highly contaminated effluent canal. Some preliminary results of a complex study of PCB health effects are: We examined 1010 adult subjects from the polluted area [PA] and 1040 subjects from control area [CA]. The mean serum level of the sum of PCBs (ng/g, lipid adjusted) in the PA (378 specimens) was 2738 and in CA (1038 specimens) 871. Thyroid volume by ultrasound (mean±SD) was significantly higher in PA (10.77±5.09 ml, 90 % = 16.6 ml) than in CA (8.99±4.11 ml; 90 % 13.3 ml; P < 0.001) and the same was true for free thyroxine [FT4] (2.04±0.37 vs. 1.91±0.37 pmol/L) and total triiodothyronine [TT3] (17.04±3.12 vs. 15.99±2.58 nmol/L). In PA also significantly higher frequency of positive antithyroperoxidase antibodies [anti-TPO] was found in males (52,7 % vs. 7.9 %-P < 0.001) as well as in females (32.0 % vs. 24.5 %-P < 0.001). However, after 4 decades of heavy exposure the average level of thyrotropin and the prevalence of abnormally increased levels (>4.0 mU/L) in both areas was the same which shows a normal thyroid function. It was concluded that, in spite of increased thyroid volume, FT4 and FT3 level and positive anti-TPO frequency, the thyroid function in great majority of exposed subjects was normal, but presumably the set points of individual short and long feedback loops were shifted which resulted in a new final steady state. After a long-term exposure of population presumably only the sequels or remnants a previous long-term process may be found. A total of 478 8–9 years old school children were recruited (119 boys and 116 girls born and living in the PA and 124 boys and 119 girls in the CA). Comparison of performance of psychological tests showed differences between areas in tests of sensomotor reactions, in short memory, and in tests of high mental processes, in favor of CA. Three main types of developmental defects of tooth enamel were recorded in children: demarcated opacities, diffuse opacities, and hypoplasia. Preliminary results showed that the percentage of children with at least one permanent tooth affected by enamel defects was 66% in the PA compared to 55% in the CA group. After finishing all analyses, for each subject will be available a large amount of data: on various organochiorines serum concentrations and their metabolites, on toxic metals serum concentrations, on thyroid status, cognitive processes, dental status, concentrations, on thyroid status, cognitive processes, dental status, hearing impairment, cytochrome P450 enzymes and xenoestrogenic activities. This will make possible exposure-effect hypothesis testing using multifactorial analysis.