Finally, although we had a larger sample size than most previous studies of PON1-mediated OP sensitivity (Lee et al. 2003; Perez-Herrera et al. 2008; Sozmen et al. 2002), this study had limited power to detect associations in the logistic regression analyses of BuChE depression and when evaluating interaction between OP/CB exposure score and PON1 status in relation to BuChE inhibition. The gene discussed is PON1; the disease is major depressive disorder.