Derivation of an Ingestion-Based Soil Remediation Criterion for CR6 Based on the NTP Chronic Bioassay Data for Sodium Dichromate Dihydrate
نویسنده
چکیده
Although the carcinogenicity of hexavalent chromium (Cr+6, Cr(VI)) by inhalation has been known for a long time, there has been little evidence regarding the potential for the carcinogenicity and no ability to estimate cancer potency of Cr+6 by ingestion until recently. The release in 2008 of the National Toxicology Program’s (NTP) chronic bioassay of rats and mice exposed to Cr+6 in drinking water provided clear evidence of cancer risk by ingestion and permits the estimation of the cancer potency and the associated soil remediation criterion. Dose-related increases in oral cavity tumors were observed in both sexes of rats and small intestine tumors were observed in both sexes of mice. Following USEPA guidance, NJDEP calculated a value for the human-equivalent cancer potency of 0.5 (mg Cr+6/kg body weight/day)-1 based on the most sensitive species and sex (male mice). For a one-in-a-million (1x10-6) lifetime cancer risk, this is equivalent to a daily dose of 1x10-6 mg Cr+6/kg body weight/day. Based on NJDEP soil remediation standards guidance, this corresponds to a soil concentration of 1 ppm (part per million). The NTP study was scientifically sound in its design and execution. Taking into account the ability of the stomach to metabolize Cr+6 to the less toxic Cr+3 form, the NTP animal data are judged to be relevant to human exposure. As per the USEPA scheme for characterization of carcinogenic potential, it is concluded that Cr+6 is “likely to be carcinogenic to humans” by ingestion. Derivation of an Ingestion-Based Soil Remediation Criterion for Cr+6 Based on the NTP Chronic Bioassay Data for Sodium Dichromate Dihydrate
منابع مشابه
Health Risk Assessment of Heavy Metals in Soil from the Iron Mines of Itakpe and Agbaja, Kogi State, Nigeria
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متن کاملHealth Risk Assessment of Heavy Metals in Soil from the Iron Mines of Itakpe and Agbaja, Kogi State, Nigeria
The study evaluates associated health risks of heavy metals in the soil to inhabitants of two mining areas of Nigeria. For so doing, it collects and analyses nine homogenous soil samples for their lead, copper, cadmium, zinc, and chromium levels, using AAS. The samples are then used to calculate health risks to adults and children. For adult population in Agbaja community, the calculated hazard...
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