Screening and prioritization of chemical hazards for deriving human health ambient water quality criteria in China.

A two-step screening and prioritization approach of the chemical hazard to derive water quality criteria for the protection of human health in China was developed. Seventy-five potential candidate chemicals were identified in Step 1, and then were screened and scored in Step 2, based on three characteristics: detection frequency, toxicity, and human exposure. Substances with a score above 900 were considered the proposed candidates. Using this approach, 18 chemicals were successfully identified, and ranked in the following order: zinc, di(2-ethylhexyl) phthalate, dibutyl phthalate, trichloromethane, arsenic, cadmium, gamma-hexachlorocyclohexane (HCH), copper, benzo[a]pyrene, lead, benzene, fluoranthene, mercury, beta-HCH, anthracene, p,p'-DDT, and alpha-HCH. Additional chemical contaminants, including thallium, antimony, chromium (VI), and nitrobenzene, suggested by the Ministry of Environmental Protection for consideration during the development of the water quality criteria, brought the final number of proposed candidates to 22. These candidates belong to different groups: nine metals, four polycyclic aromatic hydrocarbons (PAHs), four pesticides, two phthalic acid esters, one halogenated hydrocarbon, and two monocyclic aromatic hydrocarbons. This list of pollutants will provide guidance when selecting the substances to be considered during the development of water quality criteria for the protection of human health in China.