BACKGROUND - Existing methods to estimate lifetime exposure to occupational carcinogenic agents could be improved. OBJECTIVE - We propose a new method to estimate the lifetime prevalence of exposure to occupational carcinogens using the example of painters and workers of the rubber industry in France. METHODS - From census, we calculated the proportion of painters and rubber industry workers using predefined occupational codes related to each occupation by sex and 10-year age group in 1982, 1990, 1999, 2007, and 2013. Using a beta-regression model, we obtained the yearly prevalence of exposure by 10-year age group over the period 1967–2007. We estimated the age- and sex-specific lifetime prevalence of exposure of the population in 2017 over 1967–2007, summing up the estimated prevalence of exposure for years 1967, 1977, 1987, 1997, and 2007 combined with a sex- and age-specific turnover factor. Corresponding population-attributable fractions were estimated for lung and bladder cancers in 2017. RESULTS - In 2017, we estimated that 5.6 and 0.2% of men in France had ever worked as a painter or in the rubber industry, respectively, during their working time. The lifetime prevalence of ever having worked as a painter or in the rubber industry was much lower in women: 1.8% and 0.1%, respectively. We estimated that 950 lung cancer and 40 bladder cancer cases were attributable to these occupations in 2017. SIGNIFICANCE - Based on accurate data and taking into account evolution of specific jobs over time, the proposed method provides good estimates of lifetime prevalence of exposure to occupational carcinogens. It could be applied in any other country with similar data.