DEATHS AND TUMORS AMONG WORKERS GRINDING STAINLESS-STEEL - A FOLLOW-UP

Objective-To study cause specific mortality and cancer morbidity in wo rkers exposed to the dust of grinding materials, grinding agents, and stainless steel, especially with regard to a possibly increased risk o f respiratory, stomach, and colorectal cancer. Methods-Retrospective c ohort study using reference cohorts of blue collar workers and populat ion rates for comparison. The exposed cohort comprises workers with at least 12 months employment time at two plants, producing stainless st eel sinks and saucepans (n=727). Also, reference cohorts of other indu strial workers (n=3965) and fishermen (n=8092) were analysed. The obse rvation period began 15 years after the start of employment. Standardi sed mortality or incidence ratios (SMRs, SIRs; county reference rates) were calculated for cause-specific mortality between 1952 and 1993, a nd for cancer morbidity between 1958 and 1992. Results-In the exposed cohort, overall mortality, cardiovascular mortality, and all malignant mortality and morbidity were slightly lower than expected. Also, the risk estimates for cancer in the upper and lower respiratory tracts an d for stomach cancer were lower than expected. There was an increase o f morbidity from colon cancer, which was explained by an excess of tum ours in the sigmoid part only. Here, the risk estimates were higher in workers with long employment time (1-14 years: four observed cases, S IR 1.7, 95% confidence interval (95% CI) 0.4 to 4.5; greater than or e qual to 15 years: three observed cases, SHR 4.3, 95% CI 0.9 to 13) and the increased risk was especially pronounced among those first employ ed before 1942. A slight nominal excess of rectal cancers (nine observ ed cases, SIR 1.4, 95% CI 0.6 to 2.6), and a significant excess of pro state cancer morbidity (36 observed Eases, SIR 1.7, 95% CI 1.2 to 2.4) were found. These risk estimates did not, However, increase with empl oyment time. Conclusions-The finding of an increased risk of cancer in the sigmoid part of the colon, which was not found in the reference c ohorts, and with indication of a relation between duration of employme nt and response, is consistent with a causal relation. The limited siz e of the exposed cohort makes a detailed exposure-response analysis un stable, and the confidence limits are wide. Albeit slightly raised, th e risk estimate for rectal cancer in the exposed cohort was not differ ent from the estimate among the other industrial workers.