Abstract
Scientific and regulatory interest in ground water contamination by pesticides increased significantly in 1979. This was prompted by findings of the nematicide 1,2-dibromo-3-chloropropane (DBCP) and the nematicide/insecticide aldicarb (Temik) in ground water in several states. Since that time, at least 130 pesticides and pesticide metabolites have been detected in ground water in over 150 studies, but detection frequencies are 4-10% nationally. Detection frequencies of pesticides over Health Advisory Levels are generally lower. Screening-level models and detailed computer simulation models are useful for risk assessments and regulatory decisions. Attenuation Factor, CMLS, PRZM2, GLEAMS, and LEACHM are all useful models.