Lung cancer associated with chloromethyl methyl ether manufacture: an investigation at two factories in the United Kingdom.

The prevalence of deaths from lung cancer, other cancer, and all other causes was studied in workers and former workers at two factories (A and B) in the United Kingdom at which chloromethyl methyl ether has been manufactured, at one since about 1948 and at the other since 1956. At factory A in South Wales 571 men were traced and at factory B in the north east of England 1196. A statistically significant excess of observed deaths from lung cancer but not other cancer compared with the number expected was found in factory A when the death rates for the population of Glamorgan were applied. The deaths from lung cancer at factory A were related to risk in terms of total exposure time, and average exposure rate and dosage. The degree of exposure was more important than the duration of exposure. There has so far been no demonstrable excess of deaths from lung cancer in employees working at factory A since the process was changed in 1972. In factory B the risk was low over the whole period, and there was no excess of lung or other cancers compared with the rates for the Tyneside conurbation. Despite improvements in the process in both factories continued surveillance of the workers is needed for some years yet.