Hexavalent chromium in house dust — A comparison between an area with historic contamination from chromate production and background locations

In contrast to Cr+ 3, Cr+ 6 is carcinogenic and allergenic. Although Cr+ 6 can occur naturally, it is thought that most soil Cr+ 6 is anthropogenic, however, the extent of Cr+ 6 in the background environment is unknown. Cr+ 6-containing chromite ore processing residue (COPR) from chromate manufacture was deposited in numerous locations in Jersey City (JC), New Jersey. In the 1990's, significantly elevated concentrations of total Cr (Cr+ 6 + Cr+ 3) were found in house dust near COPR sites. We undertook a follow-up study to determine ongoing COPR exposure. We compared Cr+ 6 in house dust in JC to selected background communities with no known sources of Cr+ 6. Samples were collected from living areas, basements and window wells. Cr+ 6 was detected in dust from all JC and background houses. In the JC homes, the mean (± SD) Cr+ 6 concentration for all samples was 3.9 ± 7.0 μg/g (range: non-detect–90.4 μg/g), and the mean Cr+ 6 loading was 5.8 ± 15.7 μg/m2 (range: non-detect–196.4 μg/m2). In background homes, the mean Cr+ 6 concentrations of all samples was 4.6 ± 7.8 μg/g, (range, 0.05–56.6 μg/g). The mean loading was 10.0 ± 27.9 μg/m2 (range, 0.22–169.3 μg/m2). There was no significant difference between Cr+ 6 dust concentrations in Jersey City and background locations. Stratification by sample location within houses and sampling method gave similar results. Samples exceeding 20 μg/g were obtained only from single wood surfaces in different homes. Lower concentrations in window well samples suggests transport from outside is not the major source of indoor Cr+ 6. Landscaping and groundcover may influence indoor Cr+ 6. There appears to be a widespread low level background of Cr+ 6 that is not elevated in Jersey City homes despite its historic COPR contamination. It is possible that house dust, in general, is a source of Cr+ 6 exposure with potential implications for persistence of chromium allergic contact dermatitis.