POLYBROMINATED DIPHENYL ETHERS

Comments:

Polybrominated diphenyl ethers (PBDEs) are non-genotoxic substances. However, the available data on PBDEs were not adequate to allocate a PMTDI or PTWI because: (1) PBDEs represent a complex group of related chemicals and the pattern of PDBE congeners in food is not clearly defined by a single commercial mixture; (2) data were inadequate to establish a common mechanism of action that would allow a single congener to be used as a surrogate for total exposure or, alternatively, as the basis for establishing toxic equivalency factors; (3) there was no systematic database on toxicity including long-term studies on the main congeners present in the diet using standardized testing protocols that could be used to define a NOEL for individual PBDEs of importance; (4) several of the reported effects were biological outcomes for which the toxicological significance remains unclear; and (5) studies with purified PBDE congeners in vitro have shown a lack of Ah receptor activation; however, many of the adverse effects reported are similar to those found with dioxin-like contaminants, suggesting that some toxicity data may be confounded by the presence of traces of impurities that are potent Ah receptor agonists. Based on limited toxicity data, the Committee concluded that, for the more toxic congeners, adverse effects in rodents would be unlikely at doses < 100 μg/kg bw/d. The large margin of exposure between this dose level and the current estimated dietary intake levels of 0.004 μg/kg bw/d (adults) and up to 0.1 μg/kg bw/d (breastfed infants) gave reassurance that intakes of PBDEs are not likely to be a significant health concern.

Intake:

Mean: approximately 4 ng/kg bw per day for adults & up to 100 ng/kg bw/d for breastfed infants for exposure to total PBDE congeners (the Committee recognized the preliminary nature of the data on concentrations of polybrominated diphenyl ethers (PBDEs) in food and human milk, which adds considerable uncertainty to the intake estimates)

Tolerable Intake:

NONE ESTABLISHED

Meeting:

64

Report: 

Tox Monograph: