Exposure to chemical carcinogens and risk of cancer among Finnish laboratory workers.

BACKGROUND

Laboratory workers have long been suspected of having increased risks of cancer due to their occupation. We evaluated occupational exposure and cancer incidence among Finnish laboratory workers.

MATERIALS AND METHODS

The cohort was comprised of 4,722 laboratory workers reported to the Finnish Register of Workers Exposed to Carcinogens in 1979-1988. The standardized incidence ratios (SIR) for cancers and their 95% confidence intervals (CI) were calculated based on data of the Finnish Cancer Registry.

RESULTS

The most common carcinogens, to which these workers were potentially exposed, were chromium (VI), carbon tetrachloride, cadmium, benzene, and chloroform. From this cohort, 174 persons were recorded with primary tumors in 1980-1999. The SIR for cancer of all sites combined was 0.99 (CI 0.85-1.14). None of the cancer-specific SIRs were significantly elevated. Slight excesses were found, e.g., for non-Hodgkin's lymphoma (seven observed, 4.8 expected) and leukemia (four observed, three expected).

CONCLUSIONS

This study did not suggest any major cancer risks among Finnish laboratory workers but the follow-up time of the cohort was too short (on an average 15.7 years) to reveal possible cancer risks requiring a longer induction period.