Exposure of Americans to Polybrominated Dipenyl Ethers

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Polybrominated diphenyl ethers, or 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 not thought to be food and fish, but rather are from their use in household consumer products, and exposures to the high levels of PBDEs found in house dust. The exposure of Americans to PBDEs was systematically evaluated in this study. First, exposure media data on PBDE congeners were compiled. Then, an adult intake dose was derived using exposure factors in combination with these concentrations. The exposure pathways evaluated included food and water consumption, inhalation, and ingestion and dermal contact to house dust. These intakes were converted to a body burden using a simple pharmacokinetic (PK) model. The predicted body burdens were compared with representative profiles of PBDEs in blood and milk from the literature. The intake dose of total PBDEs was estimated to be 7.3 ng/kg body weight/day for adults. The predicted body burden of total PBDEs was 33.8 ng/kg lipid weight (lwt), compared to mean profiles in blood and milk at 64.0 ng/g lwt and 93.7 ng/g lwt, respectively Most of this apparent underprediction in total concentration was due to an underprediction of the key congener, BDE 47. The single literature value for BDE 47 half-life in the body was identified as the variable most likely in error in this exercise, and a calibrated value would lead to a closer match between modeled and measured body burdens. Other congener predictions compared well with measurements, suggesting general validity with the approach. An important finding from this assessment is that the food intake estimate of about 1.0 ng/kg-day (of the 7.3 ng/kg-day total) cannot explain current US body

Matthew Lorber

• by phone at:   703-347-8535
• by email at:  lorber.matthew@epa.gov