Two cohort studies on cancer risk in firefighters were recently published in OEM.1 ,2 One was a cohort of firefighters based on employment records from three US cities which had been linked with State Cancer Registries and the National Death Registry, and the other was a cohort drawn from census data from five Nordic countries which had been linked with each country's National Cancer Registries. They were both well-conducted cancer incidence studies which included large numbers of firefighters and had long follow-up periods. There were small but statistically significant increases in standardised incidence ratios (SIRs) for all cancers in both studies (SIR=1.10 95% CI 1.07 to 1.13 in the US study and 1.06 95% CI 1.02 to 1.11 in the Nordic study).

A new finding that emerged from both studies was an increase in mesothelioma. In the US study, the SIR was 2.29 (95% CI 1.60 to 3.19) and in the Nordic study it was 1.55 (95% CI 0.90 to 2.48). This increase in risk is likely to be because of the asbestos exposure occurring when buildings burn, during clean up and also perhaps a result of the asbestos protective gear which used to be widely worn by firefighters.3 These are the first studies to show a statistically significant increased risk of mesothelioma for firefighters. Worldwide asbestos production and use rose rapidly from 573 728 metric tons in 1940 to 3 493 800 in 1970.4 Firefighter exposure will therefore have become more likely over this period, and because of the long latent period between asbestos exposure and mesothelioma development, which may take over 40 years,5 the probability of contracting mesothelioma would be more likely to be identifiable in recent cohorts. Although asbestos is no longer …