Mortality among Workers Exposed to Carbon Disulfide
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Mortality experience was investigated at a plant in Ontario that produced viscose rayon, with carbon disulfide as a main raw material. Work-history records for 279 deceased workers at the plant (plant A) were obtained and compared with those for 511 deceased workers at a pulp and paper plant in the same city (plant B). In a proportional mortality analysis, using as a reference the general population of Ontario, at both plants there were fewer deaths from ischemic heart disease than expected (the proportional mortality ratios [PMRs] were 83 at plant A and 95 at plant B) but more deaths than expected from cerebrovascular disease (PMRs were 115 at plant A and 149 at plant B). In a subgroup of plant A workers who had been employed in high-carbon-disulfide exposure areas, deaths from ischemic heart disease were less than expected (PMR = 82), particularly among those who worked in these areas for more than 5 y. Most deaths occurred among those aged 65 y or more. Mortality from strokes, however, was greater than expected (PMR = 207, p < .05); the excess was confined to workers who died at age 65 y or older (PMR = 229, p = .01). Proportional mortality from strokes was also increased in the pulp workers among those who died at age 65 y or older (PMR = 153). In a case-control analysis, the risk of ischemic heart disease at plant A was slightly less than at plant B (odds ratio (OR] = 0.92, 95% confidence interval [CI] = 0.60-1.42), with no association between risk and years worked in high-carbon-disulfide areas (OR/y = 0.99, 95% CI = 0.94-1.03). Among those who died at age 65 y or older, the risk of stroke in the high-exposure subgroup was (a) increased significantly, compared with other plant A workers (OR = 4.92, 95% CI = 1.66-14.65); and (b) increased slightly, compared with plant B workers (OR = 1.37, 95% CI = 0.83-2.26). These results suggested an unusually low risk of strokes among other plant A workers. The risk of stroke was associated with years in high-carbon-disulfide areas (OR/y = 1.03, 95% CI = 0.96-1.1 0). The observed increase in proportional mortality from strokes may represent a chance finding, but a causal role for exposure cannot be excluded.