Occupational exposure to carbon black and risk of bladder cancer

Exposure to carbon black has been linked to risk of lung and bladder cancer. We therefore investigated the frequency of these cancers in a group of 2286 longshoremen who were exposed occupationally to carbon-black dust. We identified 208 cancers (standardised incidence ratio 96, 95% CI 83–109), 53 lung cancers (108, 81–141), and 32 bladder cancers (130, 89–184). Longshoremen exposed to high concentrations of carbon black (n=14) had a significantly increased frequency of bladder cancer (204, 112–343). We conclude that the increase in bladder cancer in longshoremen is probably related to high exposure to carbon black.