Human exposure to polybrominated diphenyl ethers and endocrine disruption
Makey, Colleen Marie
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Polybrominated diphenyl ethers (PBDEs) are a class of flame retardant chemicals that have been added to consumer products such as foam furniture and electronic equipment since the 1970s. Human exposure can occur when PBDEs are released to the environment. North Americans are among the most highly exposed populations, with median serum concentrations about an order of magnitude higher than European or Asian populations. Multiple animal studies have shown PBDEs to be thyroid hormone disruptors that may also adversely affect reproductive success. Limited human studies exist on the human health effects of PBDEs or their persistence in human tissues. We investigated exposure to PBDEs in a longitudinal cohort of 52 healthy adults within the Boston metropolitan area, hereafter referred to as the Flame Retardant Exposure (FlaRE) cohort. We followed individuals for approximately one year and collected serum samples and questionnaire data at three sampling intervals: Winter 2010, Summer 2010, and Winter 2011. Serum samples were analyzed for 11 PBDE congeners, thyroid function, and reproductive function tests. We used these data to assess the stability of PBDEs in serum measures, determine potential temporal trends in PBDE serum concentrations over 1 year, and assess the relationship between PBDE exposure and thyroid and reproductive function tests over time. In the FlaRE cohort, geometric mean sum concentrations of the five most prevalent PBDE congeners (BDE 28, 47, 99, 100, 153) were 21.8 ng/g lipid in Winter 2010, 22.8 ng/g lipid in Summer 2010, and 18.7 ng/g lipid in Winter 2011. We found that a single PentaBDE serum measurement is a stable estimate, either continuously or categorically, of a participant's blood concentration over the one-year study period. After adjustment of important confounders, we found that serum PentaBDE congeners were inversely associated with Total T4, which is consistent with animal experiments and some previous epidemiology studies. Among men 40 years or older, increased exposure to PentaBDEs was associated with a decrease in inhibin-B, an increase in follicular stimulating hormone, and decreases in the inhibin-B/FSH ratio thus indicating PBDE exposure may decrease testicular function in men.
Thesis (Ph.D.)--Boston University