The Pesticide Contamination Prevention Act: Setting Specific Numerical Values

Department of Food and Agriculture (CDFA) to establish specific numerical values (SNVs) for water solubility, soil adsorption coefficient (Koc), hydrolysis half-life, aerobic and anaerobic soil metabolism and field dissipation of pesticides by December 1, 1986*. Pesticides whose environmental fate properties exceed the SNVs must be reported to the State Legislature by December 1, 1987 and may be subject to further regulation if their agricultural use practices increase the probability that these pesticides will contaminate ground water. SNVs were calculated using a method that is quantitative, reproducible and verifiable by historical detection data while adhering to PCPA requirements. The procedure for calculating SNVs was accomplished in two phases. In the initial phase, pesticide monitoring studies were performed to determinewhichpesticides had been detected in ground water as a result. of agricultural use, and which pesticides have not yet been detected in ground water. Next, values for the environmental fate variables required by the PCPA were collected from published literature for over 200 active ingredients. The collected data were then entered into a data base management system for future statistical analysis. The final phase involved evaluation and selectlon of mathematical and statistical methods that could be used to determine the most appropriate criteria for identifying potential ground water pollutants. The primary concern in setting values was that the final values should correctly classi.fy pesticides according to their actual presence or absence in ground water. Therefore, a method of calculating SNVs was chosen based on a comparison of environmental fate values of common contaminants with those of non-contaminants. Comparison of environmental fate values of contaminant and non-contaminant pesticides revealed that while there are significant differences in the Koc and water solubility between the two*While collecting values on environmental fate properties, it became apparent that sufficient data for independent values of aerobic and anaerobic metabolism or field dissipation did not exist. Consequently, these categories have been grouoed together and represented by an SNV for soildegradationhalf-life. pesticide groups, there are no significant differences between the hydrolysis and soil degradation half-lives of the two groups. Based on available data, CDFA has determined that pesticides with the following average values may be classified as potential ground water contaminants : A. Soil adsorption coefficient (Koc) less than 512 cm3/ gm or water s,olubility gre,ater than 7 parts per million, and B. Hydrolysis half-life greater than 13 days or soil greater than 11 days. degradation half-life These values and the …