Recommendation from the Scientific Committee on Occupational Exposure Limits
The critical effect of the occupational inhalation of hexavalent chromium (CrVI) -containing compounds is lung cancer. In addition, occupational exposure can lead to nephrotoxicity, hypersensitivity (sensitization), corrosion of the skin, irritation of the respiratory tract and gastrointestinal tract. Cr VI compounds have been classified as a carcinogen, in Category 1 based on both humans and animal data by IARC. Most Cr VI compounds are classified by the European Union in Category 1B (substance presumed to be carcinogenic to humans). The exceptions are chromium trioxide, zinc chromate and... zinc potassium chromate which are classified in Category 1A (substance known to be carcinogenic to humans). Reevaluation of the information on the mode of action underlying carcinogenicity has resulted in the conclusion that in case of CrVI the formation of ternary DNA adducts are relevant. These DNA lesions are not easily repaired and eventually may lead to the outgrowth of repair-deficient cell clones exerting genomic instability. Thus, Cr VI acts as a directly genotoxic carcinogen for which no threshold can be assumed and for which, linear extrapolation is commonly applied by SCOEL in this situation if the available data permits.