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

As part of a large study examining the toxicity of the oil Corexit® family of oil spill dispersants on aquatic vertebrates, we examined effects on the liver using an in vitro study using a rainbow trout liver cell line. In this study, we exposed the dispersant Corexit 9500 and its major surfactant components to RTL-W1 cell lines and measured their cytotoxic effects as well as modulation of activity of one of the major enzymes responsible for organic contaminant metabolism, CYP1A. The anionic surfactant DOSS, was found to be most cytotoxic with a 24 hr 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 inducer, demonstrating the potential of these compounds to comprise the ability of exposed organisms to metabolize petroleum hydrocarbons or other CYP1A substrates.