Polybrominated Diphenylether Levels among United States Residents: Daily Intake and Risk of Harm to the Developing Brain and Reproductive Organs
Data on Polybrominated diphenylether (PBDE) concentrations in individual U.S. women were compiled. PBDE levels in adipose tissue, serum, and breast milk from individual U.S. women were found to follow similar lognormal distributions, which exhibited a high degree of variability. The distribution of lipid-normalized PBDE concentrations for all media combined had a median of 47.9 ng/g and a 95th percentile estimate of 302 ng/g. Estimates of congener-specific kinetic parameters were used to calculate the total daily intake of the PBDEs (sum of 5 PBDE prominent congeners, PBDE-47, -99, -100, -153, and -154) that would be required to achieve the measured body burdens. PBDE intake estimates from all routes of exposure were 8.5 ng/kg/d (median) and 54 ng/kg/d (95th percentile). The potential health risks posed by the PBDEs were examined by comparing 95th percentile tissue concentrations in humans (Chuman) to modeled and measured tissue concentrations in rodents that caused no developmental neurotoxicity and reproductive effects (Crodent). The ratio of rodent-to-human PBDE concentrations (Crodent:Chuman) was <1 for alterations of male and female reproductive organs in rats, <10 for neurodevelopmental effects in mice, and <100 for neurodevelopmental effects in rats. If humans are as sensitive as animals to PBDE-induced developmental toxicity, the current margin of safety appears low for a fraction of the population.