PPARA and neoplasm: Together, these results support the hypothesis that GenX induces liver toxicity via a mechanism that involves activation of PPARα, which has important implications in integrating and extrapolating data from experimental rodent studies to human risk assessment due to the species specificity of PPARα activators and tumor induction; PPARα-mediated effects on cell cycle are specific to rodents.38,39,50,51 As such, it appears that GenX operates through a PPARα mechanism indicating species specificity, an important consideration in risk evaluations or hazard assessments of the compound.