ECOTOXICITY HAZARD ASSESSMENT OF STYRENE

The ecotoxicity of styrene was evaluated in acute toxicity studies of fathead minnows (Pimephales promelas), daphnids (Daphnia magna), amphi pods (Hyalella azteca), and freshwater green algae (Selenastrum capric ornutum), and a subacute toxicity study of earth worms (Eisenia foetid a). Stable exposure levels were maintained in the studies with fathead minnows, daphnids, and amphipods using sealed, flowthrough, serial di lution systems and test vessels. The algae were evaluated in a sealed, static system. The earthworms were exposed in artificial soil which w as renewed after 7 days, Styrene concentrations in water and soil were analyzed by gas chromatography with name ionization detection followi ng extraction into hexane. Test results are based on measured concentr ations. Styrene was moderately toxic to fathead minnows, daphnids, and amphipods: fathead minnow: LC50 (96 hr), 10 mg/liter, and NOEC, 4.0 m g/liter; daphnids: EC50 (48 hr), 4.7 mg/liter, and NOEC, 1.9 mg/liter; amphipods: LC50 (96 hr), 9.5 mg/liter, and NOEC, 4.1 mg/liter. Styren e was highly toxic to green algae: EC50 (96 hr), 0.72 mg/liter, and NO EC, 0.063 mg/liter; these effects were found to be algistatic rather t han algicidal. Styrene was slightly toxic to earthworms: LC50 (14 days ), 120 mg/kg, and NOEC, 44 mg/kg. There was no indication of a concern for chronic toxicity based on these studies. Styrene's potential impa ct on aquatic and soil environments is significantly mitigated by its volatility and biodegradability. (C) 1997 Academic Press.