michael l. dourson is an american toxicologist and director of science at the nonprofit organization, toxicology excellence for risk assessment. he was formerly a senior advisor to the administrator of epa, and prior to that, a professor at the risk science center at the university of cincinnati college of medicine. prior to joining the university of cincinnati, he was founder and president of the nonprofit toxicology excellence for risk assessment. earlier in his career, he was employed by the environmental protection agency environmental criteria and assessment office, among other assignments.