Mortality and cancer incidence among laboratory technicians in medical research and routine laboratories (Sweden)

To investigate cancer incidence and mortality among laboratory employees.

Mortality and cancer incidence were investigated among 2553 female and male laboratory workers employed at the Karolinska Institute and Karolinska Hospital in Stockholm between 1950 and 1989. Mortality was followed from 1952-1993 and cancer incidence from 1958-1992. Expected numbers were based on the general population in Stockholm, standardizing for age, gender, and calendar period.

The overall mortality and cancer incidence in the cohort was lower than expected. There were in all 10 cases of hemato-lymphatic malignancies (three acute myeloid leukemias, four non-Hodgkin lymphomas, two Hodgkin's lymphomas, and one multiple myeloma) in the cohort. The standardized incidence ratio (SIR) for hematolymphatic tumors was increased among workers who had ever been employed in laboratories with a high probability for chemical exposure, SIR 224 (95% CI 108-412). The risk of breast cancer among women was increased after more than 10 years of work in high-exposure laboratories, SIR 225 (128-365). The number of malignant melanomas exceeded those expected.

The findings support earlier observations of an increased risk of hematolymphatic cancer among laboratory workers. The routine for handling chemicals and functionality of ventilatory equipment must be under continuous supervision.