PON1 and central nervous system cancer: A few previous reports addressed the possible role of PON1 polymorphisms in the risk for brain tumors: Searles-Nielsen et al. observed no main effects or interactions with insecticides for the Q192R and/or L55M SNPs, but suggested that the functional C-108T polymorphism and insecticide exposures may be important [52,53] Kafadar et al. [54] studied PON1-Q192R polymorphism and serum PON1 activity in 42 patients with high grade gliomas, 42 patients with meningioma, and 50 controls.