An epidemiologic study of employees at seven pulp and paper mills

Abstract

The cohort consisted of 11,178 Mead Corporation employees (9,358 males and 1,820 females) who had worked for at least one year between January 1, 1975 and December 31, 1992 at seven pulp and/or paper mills in the United States. The vital status of the cohort was determined through a variety of sources over an observation period of 17 years (1976-1992). Mortality data were analyzed in terms of cause-specific standardized mortality ratios (SMRs), with expected deaths based on U.S. national mortality rates. Job categories with similar exposures were created based on an historical exposure assessment. Mortality analyses were performed separately for total female and male employees. Among female employees, overall mortality was less than expected, and no significant cause-specific mortality excesses were observed. The small number of deaths among female employees did not permit further detailed analyses. Among male employees, statistically significant deficits from overall mortality (SMR = 69.0) and from all cancers (SMR = 71.3) were reported. In addition, low mortality risks for many specific causes were also observed, including many specific cancer sites, various types of cardiovascular diseases, and different forms of nonmalignant respiratory diseases. In particular, there was no mortality excess from lung cancer (SMR = 77.5), digestive cancer (SMR = 69.4), stomach cancer (SMR = 46.7), laryngeal cancer (no observed death), rectal cancer (SMR = 82.8). Hodgkin's lymphoma (no observed death), non-Hodgkin's lymphoma (SMR = 103.6), leukemia (SMR = 72.2), diabetes mellitus (SMR = 110.4), ischemic heart disease (SMR = 80.0), and nonmalignant respiratory diseases (SMR = 36.7). Furthermore, detailed analyses by length of employment, interval since hire (latency), and job category demonstrated no occupationally related mortality increases from any of the diseases examined. Specifically, based on internal comparisons, no upward trends in cause-specific mortality risk were observed by duration of employment. In conclusion, the results of this epidemiologic investigation demonstrated a favorable mortality experience for employees at the seven pulp and/or paper mills.