Atrazine and Water Quality: An Evaluation of Restricting Atrazine Use on Corn and Sorghum to Postemergent Applications, CEEPES Atrazine Project Research Memo 6

Atrazine is the most widely used herbicide for corn and sorghum and the most commonly encountered in ground and surface water. In addition to water quality problems, atrazine poses hazards through atmospheric transport, food residues, and exposure of applications and wildlife. If atrazine use is restricted, substitute herbicides will come into wider use, increasing the likelihood of occurrence of their own sets of potentially undesirable side effects and imposing cost or efficacy penalties. This report updates the CEEPES evaluation of the economic and environmental costs of restricting atrazine to postemergent applications only. The policy results summarized in this paper highlight nominal impact on the economic welfare of domestic producers and consumers and a moderate decline in the at-risk-area. In the short term the brunt of the impact was on producers, while in the long term the burden was shifted from producers to consumers. Concentrations of herbicides in groundwater were well within EPA benchmarks. Atrazine exposure index in surface water decreased markedly; however, exposures for several substitute chemicals increased, particularly simazine.