A twofold increased risk of lung and bladder cancer was reported among workers employed in coal carbonization,while no such excess was reported among other groups of workers. The same tumors were increased among gas workers from Hamburg,Germany,although the interpretation of this study is complicated by the poor reporting.In addition to a small Doanish study suggesting an increased mortality from lung cancer,a small cohort from Sweden confimed increased risk of bladder cancer, but not that of lung cancer. Increased risk of cancer from other sites has been reported occasionally in these studies; the evidence regarding skin cancer is weak mainly because most of the studies analyzed cancer mortality rather than incidence.