In eight out of ten occupations associated with exposure to coal gas, tar, pitch or soot the incidence of cancer of the bladder is greater than that found in the general male population, and in five of the ten it is from one and a half to four times as great. Three of these occupations show the highest figures for incidence of cancer of the bladder observed among the forty-six occupations investigated. Various possible sources of error in these figures are discussed, of which the most serious is the smallness of the numbers of deaths involved. The corresponding data for cancer of the prostate give less consistent indications of an occupational liability. The subject needs much further enquiry, but it has seemed best to publish now, without further delay, such material as is available, rather than wait for another long term of years while more data accumulate.

A large, and quite essential, part of this investigation, namely the computing of the population for each occupation recorded on the death certificates, and the calculation of the ratios, has been carried out by members of the staff of the Registrar General, to whom we wish to express our great indebtedness. We have to thank the British Empire Cancer Campaign for a grant which enabled the special enquiry into individual cases to be made, and to record our gratitude to those who assisted so willingly in carrying out this enquiry.