Scientific substitution of the maximum permissible concentration in soil of the modern isoxazole insecticide isocycloseram

Annotation. Isocycloseram is one of the two active ingredients of the combined insecticide Verdavis 250 ZC and belongs to highly stable compounds that can cause secondary contamination of adjacent environments of the soil. The aim of the work was to determine the threshold concentrations of isocycloseram in the soil according to translocation and general sanitary harmful index and to scientifically substantiate its medical and sanitary standard the maximum permissible concentration in the soil (MPCs). Laboratory experiments studied the behavior of isocycloseram in the soil-plant system and its effect on the nitrifying activity of leached chernozem. Vegetative experiments were conducted on test plants: wheat, oats, peas, radishes, lettuce, which were cultivated in a phytoclimatic chamber. The effect on ammonification and nitrification was studied by the dynamics of the content of ammonium ions, nitrite ions and nitrate ions in the soil. The threshold concentration of isocycloseram in soil for the translocation harmful index has been established at the level of 0.25 mg/kg. It has been proven that, subject to the established threshold concentrations in soil for water-migration (0.05 mg/kg), air-migration (more than 1.0 mg/kg) and translocation (0.25 mg/kg) harmful index, the daily intake of isocycloseram into the human body, who does not have professional contact with insecticides based on it, will not exceed: with water – 10% of the acceptable daily intake (ADI), with air – 15.0% of ADI, with food products of plant origin – 2.17% of ADI. It has been determined that isocycloseram at an initial concentration in soil of 1.0 mg/kg inhibits the processes of ammonification and nitrification; a concentration of 0.05 mg/kg is ineffective; the threshold concentration of the compound in soil for general sanitary harmful index is 0.25 mg/kg. The result of the study is a scientific justification of the MPCs of isocycloseram in soil at the level of 0.05 mg/kg according to the water-migration limiting harmful index. Compliance with the specified medical and sanitary standard in agricultural practice will prevent soil contamination and avoid secondary contamination of adjacent environments, which is dangerous for public health in the agro-climatic conditions of Ukraine.