A summary of a few relevant epidemiologic studies shows that the truck drivers and the railroad workers are apparently at most risk of lung cancer. Underground workers are also at higher risk but are exposed not only to diesel exhaust but usually to a lot of other nuisances (dust and gases).

It should be stressed that the epidemiologic studies related to diesel exhaust are challenged by a few authors who believe that the higher odd ratio for lung cancer may be due to other causes than diesel exhaust particulates.