Evaluation of Toxicity Levels and Cytotoxicity Mechanisms of Corexit 9500

Abstract

The 2010 British Petroleum (BP) oil spill in the Gulf of Mexico has raised many ecological and health concerns. BP predominately used Corexit9500A to disperse crude oil in the Gulf of Mexico to prevent shoreline contamination. The use of Corexit is a concern since the impacts of Corexit on human health and environment are unclear. This study attempts to quantify the in-vitro toxicity of Corexit by using cell lines from different tissues, and also provides data regarding toxicity mechanisms. The study provides indirect evidence on the effects of Corexit on human health effects. A 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide ( MTT ) assay was used to study the cytotoxicity effects. Reactive oxygen species ( ROS ) and lipid peroxidase ( LPO ) were measured by fluorometric and colorometric methods. Also glutathione (GSH) content and superoxide dismutase (SOD) and catalase activity were measured to develop a better understanding of toxicological pathways. Results show that the LC50 of Corexit in B16/BL6 cells is 16 ppm, in 1321N1 cells is 33 ppm, in H19-7 cells were 70 ppm, in HK-2 cells is 95 ppm, and in HEK-293 cells is 120 ppm. When H19-7 cell were treated with 80 ppm Corexit for 24 hours, ROS increased considerable (n=6, p<0.005), SOD increased (n=6, p<0.001), and catalase decreased (n=6, p<0.005). The imbalance between ROS generation and excretion indicates that the cell underwent oxidative stress, which leads to the cell death; the increase in LPO (n=6, p<0.005) verifies this assumption.