Cancer incidence among Finnish workers exposed to aromatic hydrocarbons

Objectives: To assess whether occupational exposure to aromatic hydrocarbons increases carcinogenic risk. Methods: We followed cancer incidence among 3,922 male and 1,379 female workers monitored for exposure to styrene, toluene, or xylene. The follow-up after the first personal measurement comprised 66,500 person-years at risk over the period 1973–1992. We computed the indirectly standardized incidence ratios (SIR) with 95% confidence interval (CI) with regard to age-, gender-, and period-specific incidence rates of cancer in the Finnish general population. Results: The overall rate of cancer incidence for the total cohort was fairly similar to that of the general population. The risk for nervous system tumors was increased at 10 years after the first personal measurement (SIR 2.80, CI 1.03–6.08). For styrene there was an excess risk for rectal cancer (SIR 3.11, CI 1.14–6.77), and risks for pancreatic and nervous system tumors were increased nonsignificantly. For toluene and xylene, no clear increase in cancer risk was found. Conclusions: The data are not supportive of an overall increase in the cancer risk for these solvents, even though we cannot rule out site-specific associations with the rectum, pancreas, and nervous system. There is supporting evidence in the epidemiology literature for pancreatic cancer risk and heavy exposure to styrene. More studies are warranted on solvents, with detailed information on lifetime exposures and habits being collected whenever possible.