The body of research on passive smoking continues to grow. In addition to the health effects described in the conclusions of the major reviews cited above, research evidence has linked passive smoking with the following effects on health:
A recent study estimated that non-smokers are at a 26% greater risk of lung cancer if they are married to a smoker. The risk of lung cancer in the non-smoker who lives with a smoker increases with the number of cigarettes smoked by the smoker and with the number of years they have lived together.(22b)
An Australian review of the medical evidence has confirmed that exposure to environmental tobacco smoke contributes to the incidence of childhood asthma. It may do this in the following three ways: by inducing asthma in a genetically predisposed child, by maintaining a state of increased hyper-responsiveness following exposure to an allergen, virus or irritant, and by provoking acute attacks of asthma.(23)
Measures of airways responsiveness (that is, the ability of the airways to constrict in response to certain stimuli), provide a useful indicator of the presence of asthma. Australian research has shown that the level of airway responsiveness in early life is increased with a family history of asthma, parental smoking, or both.(24)
A number of studies have pointed to an elevated risk of cancer in children of smokers, particularly leukaemia.(6) Recent research has suggested that smoking by either parent during pregnancy is associated with a higher incidence of all childhood cancers combined, but especially acute lymphocytic leukaemia and lymphoma. There may be an association between paternal smoking and brain cancer.(25) At this stage, these findings should be considered tentative.(26)
Individuals with cystic fibrosis, an inherited condition present from birth, have abnormal secretions, particularly in the lungs and intestine. For this reason, sufferers are prone to recurrent lung infections and malabsorption of food. They are frequently relatively malnourished and, typically, are shorter and lighter than unaffected individuals. They usually have increased food requirements to offset the poor absorption of food. Research has shown that children with cystic fibrosis who are exposed to tobacco smoke in the home are smaller and lighter than those not exposed, suggesting a possible link between passive smoking and growth and appetite.(27)
There is evidence that passive exposure to tobacco smoke, as well as active smoking, is a risk factor for the development of cancer of the cervix.(28) American research has shown that nicotine is present in the cervical fluid of non-smokers following exposure to passive smoking, although active smokers, who draw smoke directly into their lungs, have higher levels still.(29) The authors conclude that even low level exposure to environmental tobacco smoke may result in systemic effects.
Children exposed to tobacco smoke are more likely to be snorers and cough during the night, probably due to a chronic effect of smoke on the upper airways.(30,31)
See Chapter 3, Section 8 for discussion.