Hexabromocyclododecane (HBCD): A case study applying tiered testing for human health risk assessment.

Hexabromocyclododecane (HBCD): A case study applying tiered testing for human health risk assessment. Food Chem Toxicol. 2019 Jun 13;:110581 Authors: Gannon AM, Moreau M, Farmahin R, Thomas RS, Barton-Maclaren TS, Nong A, Curran I, Yauk CL Abstract Current global efforts are aiming to increase use of mechanistic information in regulatory testing. In tiered testing paradigms, in vitro, in silico, and in vivo studies are employed progressively to identify and classify health hazards, which are then compared against human equivalent doses. We used data from three companion papers on the brominated flame retardant hexabromocyclododecane (HBCD) to conduct a case study on tiered testing. We included ToxCast™ and in vitro-in vivo extrapolation (Tier 1), rat liver transcriptomic (Tier 2), and conventional rat (Tier 3) data. Bioactivity-exposure ratios (BERs) were derived by comparing human administered dose equivalents of the measured effects to Canadian exposure levels. Biological perturbations were highly aligned between Tiers 1/2, and consistent with apical effects in Tier 3. Tier 1 had the smallest BERs, and Tiers 2/3 were similar. The study demonstrates the promise of using physiologically-based pharmacokinetic modeling and mechanistic analyses in a tiered framework to identify pathways through which chemicals exert toxicological effects; however, they also point to some shortcomings associated with in vitro and in silico approaches. ...
Source: Food and Chemical Toxicology - Category: Food Science Authors: Tags: Food Chem Toxicol Source Type: research