On the issue of the use of health risk assessment techniques for hygienic characteristics of water supply systems

The study was aimed to assess the dynamics of risk indices for population health at main stages of surface source water treatment for centralized domestic water supply of the Leningrad region communities. Practical application issues of calculation procedure for the integrated assessment of drinking water from centralized water supply by chemical safety indices, as exemplified by Vsevolozhsk communities (Leningrad region) water supply from the Lake Ladoga and the Neva River as water sources, are discussed. Results of quality monitoring of water from centralized domestic supply system at the stage of water intake, at the output of water treatment, and in the distributing system, accomplished by Russian Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing administration and Center of hygiene and epidemiology in the Leningrad region were used as study materials. The following study techniques were used: descriptive statistics, comparative analysis, risk assessment, generalization. Microsoft Excel program was used for analysis and statistical treatment. Integral water quality index appears to be quite an informative integrated index of the efficacy of the water treatment, however, the same index value can be derived by various combinations of risk values of reflex-olfactory, non-carcinogenic and carcinogenic effects. Therefore, during the calculations, a “risk index of the effects of chronic exposure” was introduced with a view to distinguishing them from effects caused by the adverse organoleptic properties of water (reflex-olfactory effects). For the population these properties are the main reason for refusal from the use drinking water, and at the same time they are physiological, lying outside the pathology. The risk of effects of chronic exposure, carcinogenic and non-carcinogenic, expresses the probability of the development of pathology in time, but not the likelihood of an immediate refusal to use drinking water due to its unsatisfactory organoleptic qualities.