Comparison of drinking water quality in terms of relative concentrations and carcinogenic risks of trihalomethanes

An assessment of the drinking water quality according to the content of trihalomethanes on the surface and infiltration water intakes of the city of Ufa using threshold and non-threshold methods was carried out. The threshold method was estimated by calculating the summation coefficient. The non-threshold method was based on the calculation of the individual and total carcinogenic risks of the trihalomethanes components: trichloromethane, bromodichloromethane, dibromochloromethane. The summation coefficient, calculated on the content of trihalomethanes, for surface and infiltration water intakes was respectively 0.56 and 0.15. A greater contribution to the summation coefficient is made by trichloromethane. On the surface water intake, the values of carcinogenic risks are within 1.110−6 – 6.310−6, on the infiltration water intake risks are within 9.110−7 - 2.810−6, which does not exceed the maximum permissible values. A large proportion of the carcinogenic risk for the two types of water intake accounts for bromodichloromethane. The calculations show the need for measures in order to reduce the total content of trihalomethanes, primarily bromine-containing ones.