Environmental Health Aspects of Carbon Black

Abstract

Abstract Commercial carbon black is a high purity material consisting of more than 99% colloidal carbon. It differs from environmental soots in that the latter are uncontrolled mixtures of various forms of particulate carbon and relatively large amounts of organic tars, resins, and inorganic salts and oxides. Carbon black is considered to be a suspect carcinogen by incorrect analogy with high-extract soot and because it contains polynuclear aromatic hydrocarbons (PAH's), some of which are carcinogens. It is well established, however, that commercial carbon black which has only trace amounts of adsorbed PAH is neither mutagenic nor carcinogenic. Furthermore, carbon black does not cause heart disease or other major illness in animals, except for symptoms associated with lung congestion at dust levels more than tenfold greater than the OSHA PEL of 3.5 mg/ra3. Epidemiologic studies of workers exposed to carbon black dust in North America and Western Europe show no excess in mortality or morbidity due to cancer, heart disease, or respiratory disease. This is generally supported by more limited studies in the USSR and Eastern Europe, except for evidence of respiratory illness in some cases. Due to the absence of adequate control groups and exposure measurements, it is not known whether this apparent health effect results from unusual conditions of occupational exposure—high levels of carbon black and/or other substances—or is due to environmental factors (e.g., cigarette smoking).