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Passive smoking causes cancer
Written by Bupa's medical team - 20 June 2002
The World Health Organisation have revealed the results of the largest ever review of research on the effects of smoking, offering conclusive evidence that non-smokers are at risk of cancer by passive smoking.
In this review, 29 experts from 12 countries analysed more than 3,000 research papers relating to smoking and cancer. They concluded that not only were direct smokers at a higher risk than previously thought from a range of cancers, but passive smoking also increased non-smokers' risk of developing cancer by 20-30 per cent.
Commenting on the findings Professor Jonathan Samet, the chairman of the working committee and an epidemiologist at Johns Hopkins University in Baltimore said, "Typical levels of passive exposure have been shown to cause lung cancer among people who have never smoked. Secondhand smoke is carcinogenic to humans. This is the first time that an organisation with such a global sweep has reached this conclusion."
The researchers found that in addition to illnesses known to be directly caused by smoking such as lung cancer, heart disease and strokes, strong evidence also pointed towards other cancers. They added to the list myeloid leukaemia, liver cancer, stomach cancer, cervical cancer and renal cell carcinoma, a form of kidney disease.
However, the research also found clear evidence that smoking causes little or no risk of breast cancer, endometrial or prostate cancer due to their link with hormones. Sir Richard Doll, the scientist who first linked smoking to lung cancer 50 years ago said: "It does look as if the cancers that are principally caused by hormones such as breast and prostate cancer are not affected by smoking. But most of the rest are caused by exposure to chemicals."
Marsha Williams from anti-tobacco campaigning group ASH welcomed the research and raised concerns about passive smoking in the workplace, "There is no way that people should be working bathed in toxins and pollutants that scientists have today shown beyond all doubt cause cancer. Passive smoking is a carcinogen and the question to the authorities is what are they going to do about it?"
Half of all persistent cigarette smokers are eventually killed by a tobacco-related disease, this accounts for 120,000 deaths in the UK alone. Half of these deaths occur in middle age (35-69 years), when those killed by tobacco lose on average 20-25 years of life expectancy when compared with a non-smoker. The most harmful effects of smoking are avoided if smoking is stopped in the early 30's but a reduction in the health risks can be obtained even if smoking is stopped later in life.
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