Mortality among Swedish chimney sweeps (1952-2006): an extended cohort study

We extended a cohort study of Swedish chimney sweeps and prolonged follow-up in order to increase power and study those first employed after 1950 when oil began to replace wood as a main fuel for heating in Sweden.

Male Swedish chimney sweeps who were members of the national trade union in 1981-2006 were identified (n=1087) and included to a previous cohort of those employed in 1918-1980 (n=5287). All employment histories were updated, and the total extended cohort (n=6374) was linked to the registers of Causes of Death and Total Population and followed for mortality from 1952 through 2006. Standardised mortality ratios (SMRs) were estimated using the Swedish male population as reference.

1841 observed deaths resulted in an SMR for all causes of deaths of 1.29 (95% CI 1.24 to 1.36). Mortality was significantly increased for all malignant tumours, oesophageal cancer, bowel cancer, liver cancer, lung cancer, alcoholism, ischaemic heart disease, non-malignant respiratory diseases, liver cirrhosis, external causes and suicides. The lung cancer SMR remained increased, although attenuated, after adjustment for group-level smoking data, SMR of 1.52 (95% CI 1.26 to 1.89). Duration of employment showed no consistent evidence of dose-response associations. Alcohol-related deaths (liver cirrhosis and alcoholism) were not increased among those employed >30 years. Mortality among those employed after 1950 was similar to that of the entire cohort.

Chimney sweeps are exposed to high levels of toxic substances in the occupation, but excess alcohol and smoking habits were also observed, and the results must be interpreted cautiously. However, group-level data on tobacco smoking indicated that the lung cancer excess only to some extent could be explained by smoking habits, and the increased mortality from oesophageal cancer and ischaemic heart disease among chimney sweeps employed >30 years is less likely to be caused by excess alcohol habits.