Associations between CB-153 and p,p′-DDE and hormone levels in serum in middle-aged and elderly men

Background Animal and epidemiologic data indicate that exposure to persistent organochlorine pollutants (POPs) may disrupt the hypothalamus–pituitary–thyroid (HPT) and the hypothalamus–pituitary–gonadal (HPG) axes. We have assessed whether the POP-biomarkers 2,2′4,4′,5,5′-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethene (p,p′-DDE) affect thyrotropin (TSH), thyroid hormones, gonadotropins or sex hormone concentrations in men. Methods Lipid adjusted serum concentrations of CB-153, and p,p′-DDE, were determined in 196 men (median age 59 years, range 48–82). Hormone analyses in serum were performed with immunoassays. The effect of CB-153 and p,p′-DDE (as continuous or categorized variables) were evaluated by linear regression models, adjusting for potential confounders. Results There was a significant positive association between p,p′-DDE and TSH. An increase of 100 ng/g lipid of p,p′-DDE corresponded to an increase of 0.03 mU/l (95% Confidence Interval (CI) 0.01, 0.05) in TSH level. The explanatory value (R2) of the multivariate model was only 7%. Moreover, there was a significant negative association between p,p′-DDE and estradiol. An increase of 100 ng/g lipid of p,p′-DDE corresponded to a decrease of 0.57 pmol/l (95% CI −1.0, −0.12) in estradiol level. The R2-value was only 4%. No associations were observed between any of the POP biomarkers and the other hormones. Conclusions The positive association between p,p′-DDE and TSH and the negative association between p,p′-DDE and estradiol, among middle-aged and elderly men, were not accompanied by associations between the POP-markers and thyroxin, testosterone, and gonadotropins, respectively. The results gives some additional support for that POP exposure may affect HPT- and HPG-axes also in humans, but the overall epidemiological data are still not coherent enough to allow any firm conclusions.