Summary of historical terrestrial toxicity data for the brominated flame retardant tetrabromobisphenol A (TBBPA): effects on soil microorganisms, earthworms, and seedling emergence

Klaus P. Rothenbacher, Alison M. Pecquet

This article summarizes historical and recent research on the terrestrial toxicology of tetrabromobisphenol A (TBBPA). Despite its ubiquitous use and presence in the environment, little published data is available to evaluate the terrestrial ecotoxicity of TBBPA. The purposes of this paper are to enable broad access to a series of TBBPA ecotoxicity tests (nitrogen transformation, earthworm survival/reproduction, and seedling emergence/growth) that were conducted in support of regulatory risk assessments, and to summarize available research in the terrestrial toxicity of TBBPA. In these studies, no significant effect of TBBPA on nitrogen transformation was observed up to the highest concentration [1000 mg/kg dry weight (d.w.) soil]. The no-observed-effect concentrations (NOECs) for seedling emergence ranged from 20 to 5000 mg/kg d.w. Sensitivities were soybeans < corn ≈ onion ≈ tomato < ryegrass < cucumber; the most sensitive endpoints being seedling dry weight and height. The 28-day earthworm mortality NOEC was > 4840 mg/kg d.w. The most sensitive terrestrial endpoint was earthworm reproduction with a half maximal effective concentration (EC50) of 0.12 mg/kg d.w. soil. Based on this sensitive terrestrial endpoint, the EU derived a predicted no-effect concentration (PNEC) for soil of 0.012 mg/kg wet weight soil (EU 2008). We did not identify a more sensitive/lower point of departure for terrestrial toxicity endpoints in the published literature. On the basis of this PNEC, the EU concluded there was potential risk for environmental effects near TBBPA manufacturing sites, but no additional risk provided that no sewage sludge was applied to agricultural land (EU 2008).