Human health trade-offs in wellhead drinking water treatment: Comparing exposure reduction to embedded life cycle risks

Treatment of drinking water decreases human health risks by reducing pollutants, but the required materials, chemicals, and energy emit pollutants and increase health risks. This study explores human carcinogenic and non-carcinogenic disease trade-offs of water treatment by comparing pollutant dose-response curves against life cycle burden using USEtox methodology. An illustrative wellhead sorbent groundwater treatment system removing hexavalent chromium or pentavalent arsenic serving 3200 people was studied. Reducing pollutant concentrations in drinking water from 20 ?g L(-1) to 10 ?g L(-1) avoided 37 potential cancer cases and 64 potential non-cancer disease cases. Human carcinogenicity embedded in treatment was 0.2-5.3 cases, and non-carcinogenic toxicity was 0.2-14.3 cases, depending on technology and degree of treatment. Embedded toxicity impacts from treating Cr(VI) using strong-base anion exchange were <10% of those from using weak base anion exchange. Acidification and neutralisation contributed >90% of the toxicity impacts for treatment options requiring pH control. In scenarios where benefits exceeded burdens, trade-offs still existed. Benefits are experienced by a local population but burdens are born externally where the materials and energy are produced, thus exporting the health risks. Even when burdens clearly exceeded benefits, cost considerations may still drive selecting a detrimental treatment level or technology.

Authors: Gifford M, Chester M, Hristovski K, Westerhoff P. ; Full Source: Water Research. 2017 Oct 9; 128:246-254. doi: 10.1016/j.watres.2017.10.014. [Epub ahead of print]