Minnesota highway maintenance worker cohort mortality study: methods and noncancer mortality.

In 1984, the Minnesota Department of Health (MDH) began a cohort mortality study of 4,849 workers to follow up concerns with the health and safety of highway maintenance workers (HMWs). A total of 1,530 deaths had occurred, resulting in a standardized mortality ratio (SMR) of 91 (p less than .01) and an all cancer SMR of 84 (p less than .01). There was a significant elevation in the SMR for chronic renal failure among long-term rural workers (SMR = 676, p less than .05). The SMR was also elevated for transportation injuries. The latter SMR was highest among short-term urban workers (SMR = 280, p less than .01). In addition, the SMR for transportation-related injury deaths tended to increase the later the decade of starting work. The SMRs were 137, 259, 502, and 2,145 for urban workers starting work in the decades 1945-1954, 1955-1964, 1965-1974, and 1975-1984, respectively. This study demonstrates the possible adverse health effects of highway maintenance work and the need to comprehensively evaluate injury mortality among selected occupational cohorts.

Minnesota Highway Maintenance Worker Study: cancer mortality.

Highway maintenance workers (HMWs) have been exposed to a broad range of potentially toxic substances, including diesel fuels and exhaust, asphalts and tars, herbicides, gasoline, polynuclear aromatic hydrocarbons, benzene, and lead. The number of current and former state, county, and municipal HMWs in the United States exceeds 500,000, yet the health risks of this occupation had never been studied. To fill this void and to respond to the public perception that Minnesota HMWs were at high risk of developing leukemia, an occupational cohort mortality study was conducted of Minnesota HMWs employed between 1945 and 1984. Leukemia mortality in HMWs with 30-39 years of work (standardized mortality ratio [SMR] = 425; 95% confidence interval [CI] = 171-876) and urologic cancer mortality in HMWs with 40-49 year latency (SMR = 292; CI = 117-602) were significantly elevated. The extent to which these and other findings were directly related to work exposures is unknown. Further investigations to resolve the significance of the risks associated with the HMW occupation are currently underway.