An Exposure Assessment of Polybrominated Diphenyl Ethers
Author:
US Environmental Protection Agency (USEPA)
Date Published:
5/2010
Description:
Polybrominated diphenyl ethers, PBDEs, are a class of brominated flame retardants that, like other persistent organic pollutants (POPs), have been found in humans, wildlife, and biota worldwide. Unlike other POPs, however, the key routes of human exposure are thought to be from their use in household consumer products, and their presence in house dust, and not from dietary routes. The exposure of Americans to PBDEs was systematically evaluated in this study. The production and lifecycle of the formulated PBDE products were examined. Literature on their fate and presence in the environment was reviewed. Exposure media data on brominated diphenyl ether (BDE) congeners were combined with estimates of adult, childhood, and infant intake factors to estimate a total intake of PBDEs for these receptors. The exposure pathways evaluated included food and water ingestion, inhalation, and ingestion of and dermal contact with house dust. For the adult intakes, a body burden of PBDEs was simulated using a simple pharmacokinetic model. The predicted body burdens were com- pared with representative adult
profiles of PBDEs in blood and milk. The adult intake dose of total PBDEs was estimated to be 7.1 ng/kg body weight-day. Comparable published values for total PBDE exposure average 3 to 16 ng/kg-day. The estimated adult intake dose of 7.1 ng/kg-day was predicted to result in a body burden of 31.0 ng/g lipid weight (lwt). This compared to body burdens of 36.3 ng/g lwt found in blood and 44.1 ng/g lwt found in mother’s milk. Adult food intake contributes about 10% to total exposure and was estimated in this analysis to be about 0.6 ng/kg-day. Comparable published values for food intake were about 0.5 to 2.0 ng/kg-day. The largest source contributing to U.S. PBDE exposure was found to be house dust, estimated as 6.4 ng/kg-day, and contributing 90% of the overall estimated intakes. These adult intakes and body burdens were derived as central tendency estimates for the US general population. Intakes from housedust
exposures (ingestion plus dermal contact) could range up to an order of magnitude higher than calculated for this central tendency considering the highest PBDE concentrations found in dust. The 95th percentile adult body burden of total PBDEs found in the 2003/2004 National Health and Nutritional Evaluation Survey (NHANES) was 291 ng/g lwt, about an order of magnitude higher than the central tendencies of 36.3 ng/g lwt in blood. Children’s estimated intakes were higher at 47.2 ng/kg/day for ages 1–5, 13.0 ng/kg/day for 6–11, and 8.3 ng/kg/day for 12–19. Infant intakes due to ingestion of mother’s milk were the highest at 141 ng/kg/day. Other exposures of interest examined in this report include fetal exposures, occupational exposures, and unusually high exposures in the general population.
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