A simple method of establishing tolerances for pesticide residues in different countries

Abstract

At the early stage of using pesticides, some countries that do not have sufficient knowledge of the safety of pesticides may feel inadequate to establish tolerances for pesticide residues. Some published tolerances indicate that levels set for the same pesticides in different countries may vary from a few times to as high as 50 times for lindane. Furthermore, some of the tolerances are so low that they are not practical for agricultural uses. To solve these problems, the following equation was devised and accepted in Taiwan for establishing tolerances for nine pesticides applied to several vegetables. Tolerance=I_d×W_b/W_f×F_t×√P_t Where I_d is ADI (acceptable daily intake) expressed in milligrams of residues per kilogram of body weight, and obtained from the correlation of U.S. tolerances and ADI values published by FAO/WHO; W_b (in kg) is the body weight; W_f (in kg) is the daily food consumption; F_t is the percent of food treated; and P_t is the percent of a pesticide used on each group of crops. With the consideration of toxicological data, properties of pesticides, safety factors, and dissipation of residues on treated crops, temporary tolerances were established in Taiwan for parathion (0.75 ppm), methyl parathion (0.75 ppm), diazinon (0.5 ppm), lindane (5 ppm), dicofol (5 ppm), malathion (5 ppm), dichlorvos (0.5 ppm), naled (1 ppm) and mevinphos (0.75 ppm), and time intervals between the last application and harvest time were set at 14, 7, 4, 3, 2, 2, 1, 1, and 1 day, respectively. Final tolerances may be established after further studies on residues in commercial fields, in food markets, and in prepared food. Using this method of establishing tolerances, the only experimental data needed are local residue dissipation rates for each pesticide on treated crops. Other data can be obtained either from basic manufacturers or from published or unpublished statistics.