Chloromethyl ethers, cigarettes, cough and cancer

Beginning in 1963 a 10-year prospective study of 125 chemical workers was carried out by periodic screening for five years and follow-up for an additional five years. Eighty-eight men were exposed to chloromethyl ethers in varying cumulative doses estimates by retrospective rating. They were divided into three groups by degree of exposure. Age distribution was similar in all groups but the proportion of current heavy cigarette smokers at the start of observation decreased with increasing chemical exposure. The prevalence of chronic cough showed a dose-response relationship to both smoking and chemical exposure. The end-expiratory flow rate was below 60% of predicted in about one-third of the exposed men compared to only 6% of unexposed men and the frequency of such low rates was dose-related to cigarette smoking. During the five-year periodic screening study the prevalence of chronic cough decreased and the prevalence of dyspnea increased while chemical exposure was falling. The 10-year incidence of lung cancer was dose-related to chemical exposure but inversely related to smoking habits. All cancers were small-cell carcinomas, occurred in men younger than 55, and had an induction-latent period of 10 to 24 years. The 10-year mortality rate in this group of workers was 2.7 times expected and lung cancer accounted for the excess number of deaths.