Associations among urinary triclosan and bisphenol A concentrations and serum sex steroid hormone measures in the Canadian and U.S. Populations.

Exposure to triclosan, an antimicrobial agent, and bisphenol A (BPA), the monomer of polycarbonate plastics, is widespread. Endocrine-disrupting impacts of these chemicals have been demonstrated in in vitro studies, rodent toxicology studies, and some human observational studies. Here we compared urinary concentrations of triclosan and BPA in the Canadian and U.S. populations using nationally-representative data from the 2012-2015 Canadian Health Measures Survey (CHMS) and the 2013-2016 National Health and Nutrition Examination Survey (NHANES). We then examined the cross-sectional associations of urinary triclosan or BPA with serum sex steroid hormones, including estradiol (E2), progesterone (P4), and testosterone (T), using multivariable regression. We observed differences in creatinine-standardized chemical concentrations between countries; urinary triclosan was higher in Canadian females aged 12-19 years, while BPA was higher in U.S. females aged 20-49 years. We also found significant associations among urinary chemicals and serum E2 and T, but not P4. Increasing triclosan was associated with higher levels of E2 in 6-11-year-old girls, but with lower levels of E2 and T in adolescent boys aged 12-19 years. Increasing BPA was associated with lower levels of E2 in 6-11-year-old boys and in adolescents aged 12-19 years of either sex. We observed a U-shaped association between urinary triclosan and E2 in male adults aged 50-79 years; no associations between BPA and hormones were detected in adults. These results, in accordance with the in vitro and animal literature, suggest that triclosan and BPA exposures may be cross-sectionally associated with altered reproductive hormone levels, especially in children and adolescents. Further research and prospective studies are necessary to elucidate country-specific differences in chemical exposures and the potential public health significance of these findings.