10.2190/9P3M-MLL1-NVR1-F65T 9P3MMLL1NVR1F65T 125 A QUANTITATIVE RISK ASSESSMENT WITH ATTENDANT UNCERTAINTY ESTIMATIONS FOR IRRIGATED FARMLANDS IN OKLAHOMA 125 150 20030625 20030625 20030625 20030625 9P3MMLL1NVR1F65T.pdf http://baywood.metapress.com/link.asp?target=contribution&id=9P3MMLL1NVR1F65T 2 JON S. HANSON WILLIAM F. MCTERNAN Oklahoma State University, Stillwater Agricultural chemical use has increased dramatically in the post World War II era. Benefits to society include greater crop production and lower manpower requirements. Detriments include environmental and public health impacts. The subject research presents the results of a risk assessment which examined potential impacts of agricultural pesticide use. The two phase assessment focused in Phase 1 upon the projected risks associated with using six pesticides on four crop types within three hydrological soil groupings. Irrigation was compared with the dry land farming base case. The hypothetical target receptors were a "typical" farm family in Caddo County, Oklahoma; an area undergoing significant change from dry land farming to irrigated agriculture. Phase 2 addressed some of the uncertainties associated with the Phase 1 risk assessment. Both Phases utilized available transport and exposure codes to determine the probability of exceeding the U.S. Environmental Protection Agency's supported Reference Dose (RfD). Of the six pesticides evaluated only 2,4-D when used on peanuts presented potentially significant risk. Selection among the other variables such as other crops, the hydrologic soil groupings or the use of irrigation did not contribute consistently to this elevated risk. There was much uncertainty in these estimates. Phase 2 efforts showed that the exposure variables of receptor body weight and drinking water ingestion rate, together with the estimated pesticide concentration had the greatest impact on this uncertainty determination. Office of Technology Assessment, Protecting the Nation's Groundwater from Contamination, OTA-0-233, U.S. Congress, Washington, D.C., 1984. U.S. Department of Commerce, Oklahoma State and County Data, 1987 Census of Agriculture, AC87-A-36, Washington, D.C., 1989. A. Mills, Personal communication, Oklahoma State University, Stillwater, Oklahoma, 1994. J. A. Mullins, R. F. Carsel, J. E. Scarbrough, and A. M. Ivery, PRZM-2 User's Manual: Version 1.0, U.S. Environmental Protection Agency, Athens, Georgia, 1987. R. F. Carsel and R. S. Parrish, Developing Joint Probability Distributions of Soil-Water Retention Characteristics, Water Resources Research, 24:5, pp. 755-769, 1988. G. T. Yeh, AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste Transport in the Aquifer System, Publication No. 1439, Oak Ridge National Laboratory Environmental Sciences Division, Oak Ridge, Tennessee, 1981. Oklahoma Water Resources Board, Basic Data Report on Ground Water Levels in the Rush Springs Sandstone Area of Southwestern Oklahoma: Publication No. 74, Oklahoma Water Resources Board, Transcript Press, Norman, Oklahoma, 1976. J. B. Robertson, Digital Modeling of Radioactive and Chemical Waste Transport in the Snake River Plain Aquifer at the National Reactor Testing Station, Idaho, Open-file Report IDO-22054, U.S.G.S., 1974. W. J. Farmer, M. S. Yang, J. Letey, and W. F. Spencer, Hexachlorobenzene: Its Vapor Pressure and Vapor Phase Diffusion in Soil, Soil Science Society American Journal, 44, pp. 676-680, 1980. U.S. Department of Commerce, Oklahoma State and County Data, 1992 Census of Agriculture, AC92-A-36, Washington, D.C., 1994. W. F. McTernan and E. D. Mize, Simulated Effects of Irrigation Management in Groundwater Contamination, Agricultural Water Management, 20, p. 281, 1992. W. A. Pettyjohn, H. White, and S. Dunn, Water Atlas of Oklahoma, University Center for Water Research, Oklahoma State University, Stillwater, 1983. J. T. Criswell, Use of Pesticides on Major Crops in Oklahoma: Research Report P-833, Division of Agriculture, Oklahoma State University, Stillwater, 1982. R. F. Carsel, R. S. Parrish, R. L. Jones, J. L. Hansen, and R. L. Lamb, Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils, Journal of Contaminant Hydrology, 25, pp. 111-124, 1988. D. W. Connell and G. J. Miller, Chemistry and Ecotoxicology of Pollution, Wiley, New York, 1984. B. T. Daniels and W. F. McTernan, A Screening Method to Identify the Probabilities of Pesticide Leaching, Agricultural Water Management, 25, p. 23, 1994. D. Pimentel and H. Acquay, Environmental and Economic Costs of Pesticide Use, Bioscience, 42:10, p. 750, 1992. W. R. Furtick, Uncontrolled Pests or Adequate Food, in Pesticides and Human Welfare, D. L. Gunn and J. G. R. Stevens (eds.), Oxford University Press, Oxford, England, 1976. E. A. Ryan, E. T. Hawkins, B. Magee, and S. L. Santos, Assessing Risk from Dermal Exposure at Hazardous Waste Sites Superfund '87, Proceedings of the 8th National Conference, Hazardous Materials Control Research Institute, Silver Spring, Maryland, 1986. American Petroleum Institute, Decision Support System for Exposure and Risk Assessment Version 1.0, prepared by DuPont Environmental Remediation Services and Woodward-Clyde Consultants for API Health and Environmental Sciences Department, 1994. U.S. Environmental Protection Agency, Rapid Assessment of Exposure to Particulate Emissions from Surface Contaminated Sites, Report No. EPA/600/8-85/002, Office of Health and Environmental Assessment, Washington, D.C., 1985. S. A. Foster and P. C. Chrostowski, Integrated Household Exposure Model for Use of Tap Water Contaminated with Volatile Organic Chemicals, Proceedings of the 79th Annual Meeting, Air Pollution Control Association, Minneapolis, Minnesota, 1986. L. A. Gephart, J. G. Tell, and L. R. Triemer, Exposure Factors Manual, Journal of Soil Contamination, 3, p. 47, 1994. B. Yaron, General Principals of Pesticide Movement to Groundwater, Agriculture, Ecosystems and Environment, 26, p. 275, 1989. U.S. Environmental Protection Agency, Risk Assessment Guidance for Superfund, Volume 1, Human Health Evaluation Manual (Part A). Report No. EPA/540/1-89/002, Office of Emergency and Remedial Response, 1989. U.S. Environmental Protection Agency, Compilation of Ground-Water Models, Report No. EPA/600/R-93/118, Office of Research and Development, 1993.