Background. This study updates the mortality of a cohort of shoe workers exposed to organic solvents. The original study closely examined the possibility of excess leukemia mortality since toluene, a homologue of benzene, was used in the manufacturing process. That study did not find an excess for leukemia but did find a statistically significant excess of lung cancer mortality. Methods. Two shoe manufacturing plants, located in the state of Ohio (United States), were selected for this study. Both plants began operation in the 1930's, maintained adequate employment records, and conducted similar shoemaking processes. Workers that accumulated one month or more employment at either plant during the years 1940- 1979, the time period covered by work records collected by NIOSH, were included in the analysis. Vital status follow-up was ascertained through December 31, 1999 using the National Death Index and other sources. 7,828 workers, contributing 300,777 person-years-at-risk, were available for analysis. 67.5% of this cohort were female, 32.5% were male. Only five members of this cohort were non-white. Through 1999, 40% of this cohort were deceased. Analysis conducted included calculating standardized mortality ratios (SMR) for selected causes of death and tests for trend with duration of employment. Results. The original finding of excess lung cancer deaths in this cohort persisted with additional years of follow-up: SMR=1.36, confidence interval (CI)=1.19-1.54. This excess was found in both females (SMR=1.26, CI=1.04-1.52) and in males (SMR=1.45, CI=1.22-1.71). The risk was deviated in both plants but was only significant in Plant 2 workers (SMR=1.43, CI=1.22-1.66). A stratified analysis identified the highest mortality deviation among workers in Plant 2 who were employed less than two years (SMR=1.70, p<.01). Trend tests did not indicate statistically elevated positive trend between lung cancer risk and duration of employment. The use of county rates to control for the possible confounding effects of sm9king did not eliminate the lung cancer excess risk. No significant excess in leukemia deaths were found in any analysis conducted. Conclusion. This study indicates that there may be an association between lung cancer and exposure to chronic, low levels of organic solvents. Although the strength of this association is weakened by the lack of increasing lung cancer risk in relation to duration of employment, other studies have supported this association. Study limitations include the lack of detailed exposure records over time and the absence of individual smoking histories.
Work-areas; Worker-health; Workers; Chemical-hypersensitivity; Chemical-indicators; Chemical-properties; Exposure-assessment; Occupational-exposure; Occupational-health; Lung-disease; Lung-disorders; Lung-irritants; Respiratory-hypersensitivity; Respiratory-irritants; Respiratory-system-disorders; Pulmonary-disorders; Pulmonary-system-disorders; Epidemiology; Solvent-vapors; Solvents; Statistical-analysis; Risk-analysis; Risk-factors; Men; Women