A cohort mortality study of 2,283 white male workers employed at four Pacific Northwest softwood plywood mills (SIC-2436) from 1945 to 1955 was performed. Five year, age adjusted mortality rates and latency periods were determined and standardized mortality ratios (SMRs) calculated. United States mortality rates were used to determine deaths expected. The 570 observed deaths were only 74 percent of those expected. Mortality due to circulatory system disease, SMR-74, and all malignant neoplasms, SMR-70 was also below expected. Mortality for lymphatic and hematopoietic cancer, excluding leukemia, was slightly elevated, SMR-156. Two other site specific malignancies had statistically nonsignificant elevated SMRs: pancreas, SMR-138, and kidney, SMR-114. No deaths due to nasal cancer were observed, but only 0.4 deaths were expected. For the four major subgroups of lymphatic and hematopoietic cancers excluding leukemia SMRs were: multiple myeloma, 333; lymphosarcoma and reticulosarcoma, 103; Hodgkin's disease, 111; and other lymphatic cancers, 212. Mortality for lymphatic and hematopoietic cancer excluding leukemia showed excess risk most elevated after 20 years employment and latency. For the small number of workers possibly exposed to formaldehyde (50000) or pentachlorophenol (87865), an elevated risk for Hodgkin's disease was observed. The authors conclude that surveillance of this cohort should be continued and the mortality excess due to lymphoproliferative neoplasms be reevaluated.
NIOSH, Cincinnati, Ohio, 30 pages, 18 references