Development of A Reference Dose for BDE-47, 99, and 209 Using Benchmark Dose Methods

Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s benchmark dose software （BMDS） for calculation of a benchmark dose （BMD） and a benchmark dose low （BMDL）. After assessing 91 endpoints across the nine studies, a total of 23 of these endpoints were identified for BMD modeling, and BMDL estimates corresponding to various dose-response models were compiled for these separate endpoints. Thyroid, neurobehavior and reproductive endpoints for BDE-47, -99, -209 were quantitatively evaluated. According to methods and feature of each study, different uncertainty factor （UF） value was decided and subsequently reference doses （RfDs） were proposed. Consistent with USEPA, the lowest BMDLs of 2.10, 81.77, and 1698 I~g/kg were used to develop RfDs for BDE-47, -99, and -209, respectively. RfDs for BDE-99 and BDE-209 were comparable to EPA results, and however, RfD of BDE-47 was much lower than that of EPA, which may result from that reproductive/developmental proves to be more sensitive than neurobehavior for BDE-47 and the principal study uses very-low-dose exposure.