Application of superfund risk assessment techniques to production agriculture

Pesticides and nutrients applied during agricultural operations and transported from the crop field by wind and water may be result in risks to human health. Surface water and ground water pollution by pesticides and nutrients is well documented however, the magnitude of the human health effects resulting from the pollutants is usually not qualified and almost never quantified.A procedure is proposed to quantify the human health risks resulting from application of pesticides and nutrients by agriculture. The procedure is based on the methodology developed for conducting human health risk assessments on the national priorities list of sites designated under the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (42 U.S.C. §9605), also known as superfund sites.Tobacco production is chosen to demonstrate the risk assessment procedure. Human health affects resulting from application of the herbicide prowl, the fungicide ridomil and three levels of nitrogen fertilizer are characterizedIn this risk assessment, the tobacco operation is modeled with the OPUS computer model. A research scheme was designed to collect data for comparison with the OPUS parameters to assess the capabilities of the OPUS model for predicting the movement of water and contaminants. Plot studies were designed to replicate fertilizer management scenarios for tobacco production. Sampling devices were installed to collect runoff, seepage, and sediment from the plots during simulated rainfall events. The results were compared to the output of the OPUS model. It was concluded that the model is adequate for making relative risk comparisons. To quantify the uncertainty associated with the model predictions, Monte Carlo techniques are used to generate cumulative frequency distributions of the risks.The reasonable maximum exposure hazard index for an adult exposed to the pesticides is 0.08. There is a possibility of adverse health effects associated with the nitrogen fertilizer however, based on central tendency calculations the expected hazard index is less than 1. Conservative assumptions are used throughout the risk assessment, and are chosen such that estimates of risk approach the upper bound but remain within the range of possible exposures.