An epidemic of lung cancer due to chloromethyl ethers. 30 years of observation

A cohort of 125 chemical workers was established in 1963 to investigate an epidemic of lung cancer caused by industrial exposure to chloromethyl ethers (CME). Ninety-three of the men were exposed to CME, and approximate estimates of exposure were made. Standardized mortality ratios (SMRs) were calculated for lung cancer, based on Philadelphia city rates. Over 30 years of observation, 25 of 67 deaths were due to lung cancer, with a dose-response relationship. SMRs were elevated only among 59 moderately and heavily exposed workers, peaked at 23.1 in the first decade, and then declined to 7.4 and 7.9 in later decades. The mean latency period from onset of exposure to death was 21 to 25 years and was inversely related to cumulative exposure. Three of 12 heavily exposed cases occurred in nonsmokers. Small cell carcinoma accounted for 80% of the moderately and heavily exposed cases.