Objectives Research laboratory personnel is exposed to a wide variety of carcinogenic agents. The link between biological research work and a possible increased cancer risk has been studied in several European countries. We examined the incidence of cancer among persons employed in Dutch biology research laboratories, particularly cancer of the pancreas, brain, breast, and lung and non-Hodgkin’s lymphoma.

Methods In a historical cohort study, 7307 laboratory workers employed in four Dutch institutions between 1960 and 1992 were followed for incidence of cancer and mortality from 1989 to 2009 based on linkage with the Netherlands Cancer Registry. Informationon the agents used in the research laboratories was obtained by a questionnaire sent to 2536 participants (64% response) and by another questionnaire completed by 98 laboratory heads. Cancer incidence was compared with the general population via standardised incidence ratios (SIR). Internal comparisons of laboratory workers with a control group of 2404 unexposed employees of the same institutions were based on Cox regression.

Results During follow-up (mean duration, 16.6 years), 809 cancers were observed among exposed and unexposed cohort members, which affords 80% power to detect a SIR of 1.1 for all cancers among the laboratory workers and a hazard ratio of roughly 1.3 for laboratory workers compared with the unexposed group. Analyses by duration of employment, type of research lab, and job title are ongoing. Results on cancer mortality until 1995 have been previously published (Cancer Causes Control 2004;15(1):55–66). No increased cancer mortality risks were observed compared to the general population. However, based on internal comparisons, risks were elevated for several sites, particularly lung cancer.

Conclusions Strength of this cohort are the long follow-up and large size, including a sizeable control group. This allows external comparisons of cancer incidence with the general Dutch population as well as internal comparisons with similar, however unexposed, workers.