Passive smoking boosts leukaemia risk

Long-term exposure to environmental tobacco smoke may raise the risk of chronic lymphocytic leukaemia. Researchers from the Institut National de Sante Publique du Quebec, Canada, found an excess risk of leukaemia in those who were the most exposed to environmental tobacco smoke. However, when the team looked at specific subtypes of leukaemia, they did not find a clear increase of acute myeloid leukaemia, which has been linked to active smoking but a statistically significant increase of chronic lymphoid leukaemia. The researching team analysed data on 266 people with confirmed adult leukaemia, and on 1326 matched but unaffected controls for comparison. None had been smokers. There was no association between passive smoking and most leukaemia subtypes. But the chances of developing chronic lymphocytic leukaemia doubled in those with the longest exposure to residential smoking. However, it is premature to make clinical recommendations based on the results of this study because it is unknown whether these findings are real or due to chance or bias. On the other hand, there is a sufficient well-proved link between lung cancer and environmental tobacco smoke to support the recommendation to abstain from smoking in public areas.