Brominated flame retardants: Activities in a crustacean development test and in an ecdysteroid screening assay

Abstract Brominated flame retardants(BFRs) wereinvestigated for toxic effects both in vivo and in vitro in two invertebrate bioassays. Subchronic effects of tetrabromobisphenol A (TBBPA), tribromophenol (TBP), and four polybrominated diphenyl ethers ([PBDEs]; BDE‐28, BDE‐47, BDE‐99, and BDE‐100) on larval development of the marine copepod Acartia tonsa were studied. For TBBPA and TBP 5‐d effective median concentration (EC50) values for inhibition of the larval development rate were 125 and 810 μg/L, respectively, whereas the PBDEs were much more potent with 5‐d EC50 in the low μg/L range (1.2 μg/L for BDE‐100; 4.2 μg/L for BDE‐99; 13 μg/L for BDE‐28; and 13 μg/L for BDE‐47). These concentrations were up to two orders of magnitude below the 48‐h LC50 for acute adult toxicity (108 μg/L for BDE‐28; 400 μg/L for TBBPA; 520 μg/L for BDE‐100; 705 μg/L for BDE‐99; 1,500 μg/L for TBP; and 2,370 μg/L for BDE‐47). To distinguish between general toxicological and endocrine‐mediated toxic effects, the BFRs were assessed in vitro for ecdysteroid agonistic/antagonistic activity with the ecdysteroid‐responsive Drosophila melanogaster B II ‐cell line. The pentabrominated diphenyl ethers BDE‐99 and BDE‐100 showed weak ecdysteroid antagonistic activity. Thus, these PBDEs may be regarded as potential endocrine disrupters in invertebrates. The combination of in vitro assays and subchronic biotests with ecologically important crustacean species is a rapid and cost‐effective tool when screening for sublethal effects of BFRs and other chemicals.