Gender Difference in the Effects of Organochlorines and Mercury Exposure on Thyroid Hormones Levels

Abstract

ISEE-618 Objective: Organochlorines pollutants (OCs) and mercury (Hg) are widespread environmental pollutants, characterized by their accumulation in the food web chain. PCBs are known endocrine disruptors particularly with respect to thyroid function and/or action. Little data are available on thyrotoxic effects of OCs in adult men and women although recent studies have reported a striking excess of hypothyroidism and a higher prevalence of thyroid disorders in women in relation to OCs exposure. The objectives of the study are to examine THs levels in relation to blood concentrations of OCs and Hg for men and women. Materials and Methods: This cross-sectional study was carried out in 2 fishing communities in Quebec, Canada. An interviewer-administered questionnaire was used to assess species specific fish consumption and a self-administered questionnaire was used to collect sociodemographics, work and medical history. The group (N=213) consisted of 125 (59%) men and 88 (41%) women) with an average age of 49.2 ± 13.1 years old. Results: Overall, OCs concentrations were low and thyroid hormone secretion was within the normal range. For women, TT3 was negatively related to PCB-138, PCB-153, noncoplanar congeners, Arochlor 1260, dioxine-like congeners σ PCBs and DDE levels, but no relation was observed between TT4, TSH, and OCs. On the contrary, for men TT4 decreased in relation to dioxine-like congeners and σ PCBs concentrations and TSH increased significantly in relation to PCB-180, Arochlor 1260, σ PCBs, noncoplanar and dioxine-like congeners levels. However no relation was noted between TT4, TSH, and POCs. The only significant decrease of TT3 levels was in relation to σ POCs. In regard to Hg body burden, for men, a positive relationship was observed between blood total Hg and THs. Conclusions: These findings suggest that at even low levels of exposure, these persistent environmental contaminants can interfere with thyroid status and that there may be important gender differences.