Introduction. Information on the MPC (TAC) value and the limiting hazard sign is important for the analysis of the hazard of chemicals in the water of water bodies for the health of the population, serves as the basis for the development of preventive measures to ensure safe conditions for water use by the population. For the purpose of specifying the possible adverse effects of the influence of chemicals on the hygienic conditions of water use of the population, information is needed on the entire spectrum of the effects of chemicals on water quality indicators. Materials and methods. The object of the study was indicators characterizing the effect of chemicals on the organoleptic properties of water and the general sanitary regime of water bodies, algorithms for analyzing primary data to determine threshold concentrations for the effect on odor, color, turbidity, foaming, pH, general sanitary regime of water bodies - biochemical oxygen consumption, concentration of nitrogenous connections. To organize the databases, the standard apparatus of the Excel subBD electronic tables was used. The mathematical apparatus of data analysis, grouping and selection of critical indicators of limiting signs is presented. Conclusion. It is concluded that the use of databases allows to study the relationship “concentration - effect”, increases the reliability and accuracy of substantiating the threshold concentration of pollutants in water by the influence of limiting signs of harmfulness.

Introduction. The rapid growth in the production and use of pesticides poses a real risk of the possible contamination of water bodies, which determines the urgency of the improving the methods of hygienic rating of pesticide preparations in water bodies, as well as the search for screening methods for establishing threshold concentrations.The issues of the need to improve the methodological approaches to the hygienic regulation of pesticide products in water of water bodies are considered, the need for further scientific study of this issue is shown. Material and methods. There are presented results of ourselves laboratory studies on the effect of herbicides of the sulfonylurea class on the processes of self-purification of reservoirs according to the Biological Oxygen Demand (BOD) index. In the work there were used substances of the sulfonylureas derivatives with a multi-directional mechanism of action that exerts both a stimulating and inhibitory effect on the course of processes of the biochemical oxygen consumption. With the use of the formula (Gotovtsev A.V., 2016), the total biochemical oxygen consumption for sulfonylurea derivatives was calculated from the two experimentally measured BOD values. Results. The data of biochemical oxygen consumption for two substances, obtained as a result of experimental studies, are presented. Selected substances have a multi-directional effect on the course of biochemical processes: stimulation - deviation of BOD from the control (%); inhibition - deviation of BOD from the control (%). There was made an estimation of the possible use of the formula for calculating the total biochemical oxygen consumption obtained in the solution of the modified Streeter-Phelps equation system for pesticides of the sulfonylurea class. The formula was applied as a mathematical model for the predictive assessment of the establishment of threshold concentrations of pesticides on the effect on the sanitary regime of water bodies (accordingly to BOD index). Discussion. In the paper, experimental and calculated values of biochemical oxygen consumption were compared, which shows the possibility of using this mathematical method for predicting the effect of pesticidal preparations of this class on the processes of self-purification of water reservoirs. Conclusion. There was shown the possibility of using mathematical modeling methods, in particular, the modified Streeter-Phelps system of equations in the practice of sanitary and hygienic investigations.

The article highlights the methodical features of hygienic regulation of pesticide preparation in water bodies, concretizes and supplements (specified) number of positions of the acting current methodical document on hygienic evaluation of new pesticides. From the position of the comprehensive hygienic standardization there are marked principles of the study of MPC for pesticides in water bodies, there is substantiated the expediency of expanding the arsenal of methods for determination of threshold concentrations of pesticides on the impact on organoleptic properties of water and sanitary regime of reservoirs, shows the role and importance of hydrolysis processes of active ingredients ofpesticides in water, which should be considered in the assessment of the impact of drugs on the processes of self-purification of water bodies.