The threshold of toxicological concern for insufficiently explored chemicals occurring in drinking water during transportation

Finding solutions to issues of drinking water safety is a significant component in activities aimed at public health protection. In accordance with sanitary-epidemiological requirements, drinking water, in particular, should be harmless as regards its chemical composition and have favorable organoleptic properties. It is especially vital to identify risk factors for public health associated with drinking water quality. Supplying high-quality drinking water to population is a relevant problem associated, among other things, with use of new materials and reagents. The major challenge posed by their hygienic assessment is a potential growth in human health risks caused by consuming tap drinking water contaminated with migrating organic compounds. Although each of them has been detected in low concentrations, they can cause adverse chronic health outcomes. The Threshold of Toxicological Concern (TTC) is a powerful tool of risk assessment. It is based on identifying a threshold value of effects produced on human health by chemicals for which no hygienic standards have been developed so far. Below such a threshold, there is very low (95 %) likelihood of a health risk being higher than its acceptable levels. An idea of some exposure levels unable to cause adverse health outcomes is embedded in establishing maximum permissible levels (MPLs) for chemicals with known toxicological profiles. The TTC enlarges this concept by assuming that the minimum value can be identified for many chemicals based on their composition even if there is no comprehensive database on their toxicity. The TTC can be used for evaluating up-to-date materials applied in drinking water supply in order to detect risks for human health caused by consumption of drinking water that had contacts with them. Such risk assessment relies on the results of examining water extracts and involves identifying priority chemicals for their further investigation and control.