Exposure to titanium dioxide and risk of lung cancer in a population-basedstudy from Montreal

Objectives This study assessed the lung cancer risk from exposure to titani um dioxide, an important pigment with limited evidence of carcinogenicity i n experimental animals but sparse data for humans. Methods The risk of lung cancer among residents in Montreal, Canada, was an alyzed, including 857 histologically confirmed cases of lung cancer diagnos ed during 1979-1985 among men aged 35-70 years and a group of referents com prising 533 randomly selected, healthy residents and 533 persons with cance r in organs other than the lung. Exposure to titanium dioxide and other tit anium compounds was assessed by a team of industrial hygienists on the basi s of a detailed occupational questionnaire. Results Thirty-three cases and 43 referents were classified as exposed to t itanium dioxide. The odds ratio was 0.9 [95% confidence interval (95% CI) 0 .5-1.5]. No trend was apparent according to the estimated frequency, level, or duration of exposure. The odds ratio was 1.0 (95% CI 0.3-2.7) for mediu m or high exposure for at least 5 years. Few subjects were classified as ex posed to titanium dioxide fumes or to other titanium compounds, but the ris k of lung cancer was nonsignificantly increased for exposure to these agent s. Conclusions Although misclassification of exposure and low exposure prevale nce might have resulted in false negative results, this study does not sugg est that occupational exposure to titanium dioxide increases the risk of lu ng cancer.