Human exposure to polybrominated diphenyl ethers (PBDE), as evidenced by data from a duplicate diet study, indoor air, house dust, and biomonitoring in Germany.

Polybrominated diphenyl ethers (PBDE) are used as flame retardants in a wide variety of products. As part of the Integrated Exposure Assessment Survey (INES), this study aimed to characterize the exposure of an adult German population using duplicate diet samples, which were collected daily over seven consecutive days, and indoor air and house dust measurements. Our study population consisted of 27 female and 23 male healthy subjects, aged 14-60 years, all of whom resided in 34 homes in southern Bavaria. In these 34 residences the air was sampled using glass fiber filters and polyurethane foams and the dust was collected from used vacuum cleaner bags. The median (95th percentile) daily dietary intake of six Tetra- to HeptaBDE congeners was 1.2 ng/kg b.w. (3.3 ng/kg b.w.) or 67.8 ng/day (208 ng/day) (calculated from the 7-day median values of each study subject). Concentrations in indoor air and dust (cumulative Tri- to DecaBDE congener readings) ranged from 8.2 to 477 pg/m(3) (median: 37.8 pg/m(3)) and 36.6 to 1580 ng/g (median: 386 ng/g), respectively. For some congeners, we identified a significant correlation between air and dust levels. The median (95th percentile) blood concentration of total Tetra- to HexaBDE congener readings was 5.6 (13.2)ng/g lipid. No significant sex differences were observed, but higher blood concentrations were found in younger participants. Using a simplified toxicokinetic model to predict the body burden from exposure doses led to results that were of the same order of magnitude as the measured blood concentrations. Based on these measurements and given our exposure assumptions, we estimated for the total tetra- to heptabrominated congener count an average (high) comprehensive total daily intake of 1.2 ng/kg b.w. (2.5 ng/kg b.w.). Overall, our results suggest that dietary exposure is the dominant intake pathway at least in our study population, responsible for 97% (average intake) and 95% (high intake) of the total intake of an adult population.

Developmental exposure to low-dose PBDE-99: tissue distribution and thyroid hormone levels.

Thyroid hormone concentrations, hepatic enzyme activities and tissue concentrations of 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99) were evaluated in Wistar rats (dams and offspring) after treatment by gavage on gestation day (GD) 6 with a single low dose of either 60 or 300 microg PBDE-99/kg body weight (bw), respectively. Tissue concentration analysis confirmed that PBDE-99 is persistent in rodents as significant amounts of the parent compound were detected in adipose tissue 37 days after exposure. The dose of 300 microg PBDE-99/kg bw reduced thyroxin (T4) concentration in dams at the beginning of lactation (post-gestational day [PGD] 1), and caused a slight reduction in T4 on PGD 22, although not statistically significant. In offspring, reduced T4 was observed only at PND 22, probably due to cumulative effects of PBDE-99 during lactation. PBDEs have been shown to reduce T4 concentrations in several studies, but this is the first study demonstrating endocrine disruption at low doses. The adipose tissue concentration of PBDE-99 measured in this study was close to those reported for PBDE-99 in non-occupationally exposed humans. In addition, we have previously reported permanent changes in the reproductive systems and locomotor activity of male and female offspring using these same dosages.