Deterministic Chemical Risk Assessment of Emerging Contaminants in Drinking Water: Global Guidelines

Emerging contaminant classes in drinking water, including pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), and endocrine disruptors, are of global public health concern because emerging contaminants can be extremely stable and toxic even at very low concentrations. This chapter examined deterministic chemical risk assessment, a point-estimate approach for establishing health-based guidance values for emerging contaminants. There are four steps in this framework: hazard identification, dose-response assessment, exposure assessment, and risk characterization (which provides a single protective value such as a hazard quotient). The analysis assessed international regulatory standards from groups such as WHO (World Health Organization), USEPA (United States Environmental Protection Agency), and the European Union and highlighted concordance in scientific principles and differences in regulatory application and enforcement. While deterministic risk assessment is valued because it is simple and conservative, it also overestimates risk and does not characterize uncertainty. The chapter goes on to conclude that improved detection techniques and harmonization to develop global standards and approaches to emerging contaminants are needed and that currently available advanced methods should be used to improve risk assessment approaches in the future and ensure safe drinking water for all.