International Agency for Research on Cancer (IARC) recently evaluated the carcinogenicity of three poorly soluble low-toxic substances: carbon black, cosmetic talc or titanium dioxide. Though there is sufficient evidence of carcinogenity in experimental animals for these substances, the evidence in humans is sparse and equivocal. In the context of two large population based case-control studies of lung cancer carried out in Montreal, we are able to study the possible relationships between the exposure to each of carbon black, cosmetic talc or titanium dioxide and subsequent risk of lung cancer. Interviews for Study I were conducted in 1979-86 (857 cases, 533 population controls, 1349 cancer controls) and interviews for Study II were conducted in 1996-2001 (1236 cases and 1512 controls). Detailed lifetime job histories were elicited, and a team of hygienists and chemists evaluated the evidence of exposure to a host of occupational substances, including carbon black, cosmetic talc, and titanium dioxide. Lung cancer risk was analyzed in relation to each exposure, adjusting for several potential confounders, including smoking in a three-variable parameterization. For all three substances, in both sexes, the estimated odds ratios were close to the null value, with none significantly elevated. Our results support the hypothesis that exposure to carbon black, cosmetic talc, or titanium dioxide are not risk factors for lung cancer in humans. The results corroborate the recent evaluations of the IARC Monographs.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA