title: Exposure to chromium (VI) in the drinking water increases susceptibility to UV-induced skin tumors in hairless mice.
abstract: Hexavalent chromium (Cr (VI)) is a well known-human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for occupational exposure via inhalation, the carcinogenic hazard of drinking water exposure to Cr (VI) has yet to be established. We used a hairless mouse model to study the effects of K(2)CrO(4) in the drinking water on ultraviolet radiation (UVR)-induced skin tumors. Hairless mice were unexposed or exposed to UVR alone (1.2 kJ/m(2)), K(2)CrO(4) alone at 2.5 and 5.0 ppm, or the combination of UVR and K(2)CrO(4) at 0.5, 2.5, and 5.0 ppm. Mice were observed on a weekly basis for the appearance of skin tumors larger than 2 mm. All the mice were euthanized on day 182. The skin tumors were excised and subsequently analyzed microscopically for malignancy by histopathology. There was a total absence of observable skin tumors in untreated mice and in mice exposed to chromate alone. However, there was a dose-dependent increase in the number of skin tumors greater than 2 mm in mice exposed to K(2)CrO(4) and UV compared with mice exposed to UV alone. The increase in tumors larger than 2 mm was statistically significant (P < 0.05) for UV and K(2)CrO(4) at the two highest K(2)CrO(4) doses (2.5 and 5.0 ppm), and there was a statistically significant increase in the numbers of malignant tumors per mouse in the UVR plus K(2)CrO(4) (5 ppm) group compared with UV alone. The data presented here indicate that K(2)CrO(4) increases the number of UV-induced skin tumors in a dose-dependent manner, and these results support the concern that regulatory agencies have relative to the carcinogenic health hazards of widespread human exposure to Cr (VI) in drinking water.
authors.affiliation: Nelson Institute of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10016, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Davidson
authors.forename: Thomas
authors.initials: T
authors.lastname: Kluz
authors.forename: Fredric
authors.initials: F
authors.lastname: Burns
authors.forename: Toby
authors.initials: T
authors.lastname: Rossman
authors.forename: Qunwei
authors.initials: Q
authors.lastname: Zhang
authors.forename: Ahmed
authors.initials: A
authors.lastname: Uddin
authors.forename: Arthur
authors.initials: A
authors.lastname: Nadas
authors.forename: Max
authors.initials: M
authors.lastname: Costa
mesh_terms: D000818:Animals; D002840:Chromates / Q000633:toxicity*; D004198:Disease Susceptibility / Q000139:chemically induced*; D005260:Female; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000473:pathology; D017680:Potassium Compounds / Q000633:toxicity*; D012878:Skin Neoplasms / Q000209:etiology* / Q000473:pathology; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D002840:Chromates; D017680:Potassium Compounds; D014874:Water Pollutants, Chemical; C027373:potassium chromate(VI)