The most important epidemiologic study to date on coke oven workers has been conducted since the 1960s in the US and Canada. A recent update of this cohort shows a twofold increased risk of lung cancer , that decreased during the follow-up. An analysis of lung cancer risk according to cumulative exposure to coal-tar pitch volatiles, based on measurements taken in the plants of the study in the late 1960s, showed a monotonic, significant dose-response. In another large cohort study, from China, the risk of lung cancer was increased between two-and fourfold, according to the department in which the subject worked. Similar results were obtained in two smaller studies from Italy and France, while the risk of lung cancer was increased only moderately (30 percent) in other studies from Netherlands and Japan.