Human Health Water Quality Criteria: Research Challenges and Priorities

Human health water quality criteria (HHWQC) define safe contaminant levels in surface water to protect human health and are a crucial foundation for water environment management. However, many countries lack methods for deriving HHWQC. This Perspective reviews recent advancements and proposes a set of scientific methodologies. To enhance the scientificity and practicability of HHWQC, four key challenges and priorities are identified. (i) Region-based parameters are essential for reflecting local environmental conditions and exposure patterns, yet they are often lacking in many countries, necessitating comprehensive fundamental databases. (ii) The increasing environmental contaminants make it challenging to derive toxicological reference values (TRVs) using traditional animal experiments, which may be addressed by integrating in vitro high-throughput bioassays with PBPK models. (iii) Default uniform values for relative source contribution (RSC) may under- or overestimate HHWQC, which could be refined by incorporating external and internal exposure assessments. (iv) Deterministic methods commonly used for HHWQC derivation are considered inaccurate and rudimentary, whereas probabilistic approaches are more effective in accounting for uncertainty and variability in input variables. This paper is essential for advancing the scientific development of HHWQC and improving the global water environment protection and management system from a human health perspective.