Thyroid function in relation to burden of PCBs, p,p′-DDE, HCB, mirex and lead among Akwesasne Mohawk youth: A preliminary study

The effects of endocrine disrupting environmental contaminants such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), p,p′- dichlorophenyldichloroethylene (p,p′-DDE), mirex, and lead, are examined in a sample of youth of the Akwesasne Mohawk Nation who are 10-16.9 years of age (n = 115). The Akwesasne community is located adjacent to hazardous waste sites where PCBs and other toxicants have contaminated the local ecology. This study examines the relationship between measures of thyroid function and endocrine disrupting environmental toxicants. Both with and without statistical adjustment for other toxicants, as well as age, sex and lipid levels, several indicators of PCB burden are significantly, negatively related to levels of free thyroxine and total thyroxine, and positively to thyrotropin. Lead level was positively related to triidothyronine. Future testing of non-linear relationships is warranted. Despite the linear associations with thyrotropin, free and total thyroxine, PCBs were not related to increased occurrence of these hormones outside the clinically normal range for the testing laboratory.