[Classification of hazards of water pollutants].

The paper considers materials on the substantiation of criteria, indices, and their gradation for a new variant of the hygienic classification of hazards of water-contaminating substances. Emphasis is placed on the significance of a ratio of the maximally inactive concentrations (MIC) in terms of the toxicological sign of harmfulness to the threshold concentrations (TC) in terms of their effects on the organoleptic properties of water and on the general sanitary regime of water reservoirs. Only two types of late effects of substances, which are of individual significance for classification, such as carcinogenicity and reproductive effects, are identified. It is stated that a class of hazard may be toughened for high-stable substances, but neither the stability nor any other indices of the potential hazard of substances is the ground for reducing their hygienic standards in water.