Different studies have attributed varying risks to the non-smoker of developing lung cancer due to passive smoking, depending on how the researchers have classified levels of exposure. The National Research Council in the United States has reviewed and evaluated those studies which allow cross comparisons, and have put the 'best estimate' of relative risk for non-smokers developing lung cancer due to passive smoking at 1.42 (meaning that exposed non-smokers have a 42% higher risk of getting lung cancer than non-exposed non-smokers).(34)
From a 1986 review of the available epidemiological studies of lung cancer and passive smoking, researchers have concluded that about one third of lung cancer cases in non-smokers who live with smokers, and about a quarter of the cases in non-smokers in general, may be attributed to exposure to environmental tobacco smoke.(35)
Two studies have estimated that about 140 deaths from lung cancer annually may be attributed to passive smoking in Australia.(36,37) The first, using mortality data from the United States, calculated that in 1983, 136 Australian deaths from lung cancer could be attributed to passive smoking. Of these, approximately 60 deaths were among non-smokers and 76 among current or ex-smokers.(36)
The report concluded with the following comment:
This total of 136 deaths is quite small. The deaths are, however, preventable. In addition, they do not appear to be quite so few when compared with the 56 deaths attributed to the personal use of opiates in 1980 and the estimated total of 281 deaths from mesothelioma and lung cancer caused annually by all forms of exposure to asbestos in Australia. It seems appropriate that public health action should now be turned to passive smoking.
A more recent estimate has placed the number of deaths due to lung cancer arising from passive smoking at 146 deaths in 1986.(37)
The draft National Health and Medical Research Council report has come up with lower figures. However, these estimates only take into account exposure by never smokers to a partner smoking in the home. This exposure alone is estimated to cause around ten new cases of lung cancer and eight lung cancer deaths each year in never smokers. (14)
Environmental tobacco smoke is a major cause of cancer compared to other environmental health risks. It has been estimated that non-smokers have a 25% higher risk of developing cancer from exposure to ETS than from indoor radon, and that this risk is about 57 times greater than the combined estimated cancer risk from all the hazardous outdoor air pollutants currently regulated by the US Environmental Protection Agency: airborne radionuclides, asbestos, arsenic, benzene, coke oven emissions, and vinyl chloride.(38) British researchers Peto and Doll have expressed the risk of developing lung cancer from passive smoking as being about 90 times higher than the risk of developing an asbestos-related cancer due to asbestos in buildings.(39)
An American review of the epidemiological evidence linking passive smoking with cardiovascular disease has estimated that passive smoking causes around ten times as many deaths from heart disease as it does from lung cancer.(18) If exposures to passive smoking in the US are similar to Australia, up to 1,400 deaths due to heart disease could occur.
The draft National Health and Medical Research Council reports that passive smoke exposure by never smokers to a smoking partner in the home accounts for 100 deaths and 160 hospital admissions for a major coronary event in Australia each year.(14)