Rapid Toxicity Evaluations of Several Dispersants: A Comparison of Results

Abstract

ABSTRACT During the Deepwater Horizon incident, dispersants were applied to floating oil and injected into the oil plume at depth. These decisions were carefully considered by state and federal agencies, as well as BP, to prevent as much oil as possible from reaching sensitive shoreline habitats. Nearly three weeks after dispersant use was initiated, the U.S. Environmental Protection Agency (EPA) directed BP to evaluate alternative dispersants to the Corexit product(s) that had been used. BP developed a screening strategy to consider all dispersants listed on the National Contingency Plan (NCP) Product Schedule. The criteria considered: a) product availability, b) dispersant effectiveness on MC252 oil, c) potential biodegradation products, and d) aquatic toxicity. This paper discusses the final criterion, aquatic toxicity. BP and the EPA contracted laboratories to conduct toxicity screening of several NCP dispersants using slightly different laboratory protocols adapted from on Singer et al. (2000). The B...