Cytotoxicity and CYP1A inhibition in rainbow trout liver (RTL-W1) cell lines exposed to dispersant Corexit 9500 and its major surfactant components

- DOSS is the most cytotoxic surfactant in Corexit 9500 in RTL-W1 cells.
- Tween 80 and 85 also inhibit benzo[a]pyrene induced CYP1A activity.
- These surfactants in Corexit 9500 could compromise health of larval fishes.

As part of a large study examining the toxicity of the Corexit® family of oil spill dispersants on aquatic vertebrates, we examined effects on the liver in an in vitro study using the rainbow trout liver cell line (RTL-W1). We exposed RTL-W1 cells to the dispersant Corexit 9500 and its major surfactant components and measured their cytotoxic effects as well as modulation of activity of CYP1A, one of the major enzymes responsible for organic contaminant metabolism. The anionic surfactant DOSS was found to be the most cytotoxic with a 24 h EC50 of 10 mg/L, as compared to 45 to 91 mg/L for the non-ionic surfactants, Tween 80 and 85 and Span 80. The EC50 for Corexit was intermediate between these compounds at 29 mg/L. Corexit 9500 and the non-ionic surfactants Tween 80 and 85, but not DOSS or Span 80 knocked down CYP1A activity induced by benzo[a]pyrene, a model agonist, demonstrating the potential of these compounds to compromise the ability of exposed organisms to metabolize petroleum hydrocarbons or other CYP1A substrates.