Total chromium and hexavalent chromium occurrence analysis

Abstract

Total and hexavalent chromium occurrence in the United States was investigated using three datasets-the National Chromium and Boron Survey (NCBOS), the US Environmental Protection Agency (USEPA) database of chromium from the second six-year review (6YR2), and California Department of Public Health (CDPH) water quality analysis database (WQAD). Chromium was found to occur widely. The high number of nondetect (ND) samples and subsequent ND handling affected the determination of representative chromium concentrations. Total and hexavalent samples were paired, and they indicated that surface water speciation is dominated by trivalent chromium [Cr(III)], whereas groundwater speciation is dominated by hexavalent chromium [Cr(VI)]. The potential impact of further chromium regulation ranges more than two orders of magnitude with as few as 1,000 entry points (EPs) being affected nationwide at 20 μg/L and as many as 100,000 at 1 μg/L.