Pipes could release toxic chromium into tap water

Abstract

A new study shows that the carcinogen hexavalent chromium can slip into drinking water when commonly used chlorine disinfectants corrode cast-iron water distribution pipes ( Environ. Sci. Technol. 2020, DOI: 10.1021/acs.est.0c03922 ). Until now, most scientists thought that chromium found in drinking water originated from natural sources or industrial pollution. Haizhou Liu and his team at the University of California, Riverside, found another possible source by scraping some of the crusty scale out of two sections of cast-iron pipes from US drinking water systems. Cast iron is widely used in these pipes and contains significant amounts of Cr(0) in the alloy to help prevent corrosion. The scientists incubated the scale samples in a solution of hypochlorous acid, the oxidizing sanitizer commonly used to treat drinking water. The disinfectant-treated scales rapidly cranked out Cr(VI), whereas scales in water with no disinfectant produced none of the toxic metal species. Also, when exposed