Mortality patterns among workers exposed to chloromethyl ethers--a preliminary report.

Chloromethyl methyl ether (CMME) has been used extensively as a crosslinking agent for ion-exchange resins. Commercial grades of CMME are contaminated to the extent of 2-8% with bischloromethyl ether, an alkylating agent which has been shown to be a very potent lung carcinogen in animals. Reports by other investigators in this and other countries have implicated CMME as a lung carcinogen in chemical workers. The purpose of the study reported here was to examine the lung cancer mortality experience with respect to intensity and duration of exposure in six of the seven chemical companies that account for virtually all of the CMME use in the United States. The study included about 1800 workers who were exposed in the period 1948 to 1972 and about 8000 workers not exposed to CMME from the same plants who served as controls. Exposed workers were characterized according to job description and duration of exposure. In several plants the intensity of exposure was numerically graded for each job category with adjustment for temporal changes in the plant processes. Social Security records were used to identify deaths among workers who had left the companies and death certificates have been obtained for virtually all known deaths. The age-adjusted death rate for respiratory cancer in the CMME exposed group as a whole was 2.5 times that in the control group, whereas death rates due to other causes were comparable. There was also a gradation of lung cancer risk according to intensity and duration of exposure and the time elapsed since the onset of exposure.