Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5561208 | Regulatory Toxicology and Pharmacology | 2017 | 7 Pages |
â¢A Reference Dose was derived for 2-ethylhexyl-2,3,4,5 tetrabromobenzoate (TBB).â¢A Biomonitoring Equivalent (BE) was derived for tetrabromobenzoic acid in urine.â¢The BE for TBBA is 2.5 mg/L and 2.5 mg/g cr.
2-ethylhexyl-2,3,4,5 tetrabromobenzoate (TBB) is used as a flame retardant. Biomonitoring for TBB exposures include the metabolite, tetrabromobenzoic acid (TBBA), in urine. We derived a Reference Dose (RfD) for TBB and a Biomonitoring Equivalent (BE) for TBBA in urine. Three longer-term studies of oral gavage dosing of a commercial mixture BZ-54 (which includes 70% TBB) in rats were evaluated for deriving the RfD. The 95% lower confidence limits on the BMD associated with a 1 SD change from the mean (BDMLSD) values ranged from 77 to 134Â mg/kg-day. The mean BMDLSD value of 91Â mg/kg-day for maternal body weight changes was selected as the appropriate point of departure (POD), corresponding to a human equivalent dose (PODHEC) of 25Â mg/kg-day. A total composite uncertainty factor (UF) of 300 yields an RfD of 0.08Â mg/kg-day. A urinary mass excretion fraction (Fue) of 0.6 for TBBA following oral doses of TBB in rats was used to calculate BEs for TBBA in urine of 2.5Â mg/L and 2.5Â mg/g cr. Mean (5.3Â ÃÂ 10â6Â mg/L) and maximum (340Â ÃÂ 10â6Â mg/L) levels of TBBA measured in urine from human volunteers reported in the literature indicates margins of safety (MOS) are approximately 450,000 and 7,000, respectively.