Cancer incidence and mortality in the Du Pont Company: an update.

In a previous publication, Pell et al described the cancer epidemiologic surveillance program that was begun in the Du Pont Company in 1956 and presented standardized cancer incidence and mortality data through 1974 for Du Pont employees compared with such data for the US general population. This report provides the analysis of an additional 10 years of cancer incidence and mortality data, and examines time trends for specific cancer sites. Conoco, Inc, acquired in 1981, is not included in the analysis.

Cancer incidence and mortality among workers exposed to acrylonitrile.

A cohort of 1,083 male employees who had potential for exposure to acrylonitrile between 1944 and 1970 at a Du Pont textile fibers plant were followed through 1981 for mortality and through 1983 for cancer incidence. In total, the 21 cancer deaths were fewer than expected based on either Du Pont or U.S. rates. No significant excesses were seen by primary site. In all, 37 cancer cases occurred as compared with 36.5 expected based on company rates. Five lung cancer cases were observed and 6.9 expected. There were 5 prostate cancer cases as compared with 1.9 expected. Of these, 4 occurred among wage employees during the 1975-1983 period, compared to 0.9 expected. This excess was statistically significant.

Mortality among industrial workers exposed to formaldehyde.

A historical cohort study evaluated the mortality experience of 26,561 workers employed in 10 formaldehyde-producing or -using facilities. Approximately 600,000 person-years of follow-up accrued as workers were followed to January 1, 1980. Estimates of historical exposure to formaldehyde by job were developed by project industrial hygienists using monitoring data available from participating plants, comments from long-term workers, and comprehensive monitoring data specifically collected for this study. Mortality from all causes combined was about as expected [standardized mortality ratio (SMR) = 96] based on mortality rates of the general U.S. population. Significantly fewer deaths occurred from infective and parasitic diseases (SMR = 51) and from accidents (SMR = 72) than expected. Cancer overall was not related to formaldehyde exposure. Workers exposed to formaldehyde had slight excesses for Hodgkin's disease and cancers of the lung and prostate gland, but these excesses were not consistently related to duration of or average, cumulative, or peak formaldehyde exposure levels. Recent animal studies found nasal cancer among rats exposed to formaldehyde, but no excess of this tumor occurred in this study. Mortality from brain cancer and leukemia among these industrial workers was not excessive in contrast to reported excesses among professional groups (e.g., anatomists, embalmers, and pathologists) with exposure to formaldehyde. Although there was a deficit for cancer of the buccal cavity and pharynx, mortality from certain subsites, i.e., the nasopharynx and oropharynx, was elevated. These subsites did not, however, show a consistently rising risk with level of exposure. These data provide little evidence that mortality from cancer is associated with formaldehyde exposure at levels experienced by workers in this study.

Epidemiologic study of workers exposed to acrylonitrile: an update.

A previous report presented the cancer morbidity and mortality experience through 1976 of a cohort of 1,345 male employees with potential for exposure to acrylonitrile at a fibers-producing plant. This study has now been updated through 1983 for cancer incidence and through 1981 for mortality. Overall, 43 cancer cases have occurred, with 37.1 expected based on company rates. A previously reported excess number of cases of lung cancer remains, but is not as marked (10 observed, 7.2 expected). Prostate cancer cases were significantly in excess, with six cases observed and 1.8 expected. Mortality analyses revealed 36 cancer deaths, with 31.6 expected. Of these, 14 were from lung cancer, with 11.6 expected based on company rates. Only one death from prostate cancer occurred, with 1.0 expected. To our knowledge, prostate cancer excesses have not been reported in any other acrylonitrile studies, and hence their significance is currently difficult to assess.

Epidemiologic study of workers exposed to acrylonitrile.

This retrospective cohort study of 1,345 male employees with potential for exposure to acrylonitrile analyzes cancer incidence and mortality from 1956 to 1976. Expected numbers based on company and national rates have been computed on person-years. The analyses consider calendar time, payroll classification, occupation, duration of exposure, severity of exposure, and latency. Overall, 25 cases of cancer occurred, with 20.5 expected based on company rates. Of these, eight were respiratory cancer cases, with 4.4 expected. Excesses were found primarily during the 1970-76 time period among wage roll employees who had worked during plant start-up. A trend toward increased risks was seen with increased duration and severity of exposure. Twenty cancer deaths were found, with 17.4 expected according to company rates. Since many cancer cases were recently diagnosed and are living, it may be premature to evaluate mortality statistics. These findings, coupled with results from tests in laboratory animals, raise the serious suspicion that acrylonitrile may be a human carcinogen.