Their report, which contradicts previous findings, was immediately attacked by anti-smoking campaigners and cancer charities who described it as "appalling" and noted it had been funded by three big tobacco companies.
Passive smoking has been a fiercely contested issue in recent years. In 1992 the US Environment Protection Agency classed Environmental Tobacco Smoke as a class-A carcinogen, estimating it caused 3,000 deaths a year. Many public areas, such as restaurants, aeroplanes and railways, have banned smoking.
Although no case linking passive smoking and lung cancer has been won in Britain, last year Beryl Roe and Veronica Bland, employed by Stockport Council, won pounds 25,000 and pounds 15,000 for bronchial illnesses caused by passive smoking.
The European Working Group on Environmental Tobacco Smoke and Lung Cancer, analysed all 48 epidemiological studies on ETS and cancer published to date and measured exposure to ETS. They did not look at links to diseases such as bronchitis and emphysema.
They concluded that the relative risk of those who lived with a smoker contracting the disease was "statistically insignificant".
Professor Jeffrey Idle, chairman of the European Working Group, said when the group evaluated the spousal studies [mostly among non-smoking women living with men who smoke] the group concluded there was a relative risk of 1.01, where 1.0 means a zero increase in risk. In studies on workplace smoking, the group put the relative risk at 1.04.
"Relative risks of 1.01 and 1.04 are virtually meaningless in scientific terms," Professor Idle said.
Dr Richard Springall, an independent consultant in statistics, said past studies failed to account for biases in the data.
The group was commissioned by three tobacco companies, Philip Morris Europe SA, British-American Tobacco Limited and Rothmans International. Professor Idle said the scientists had conducted the study on condition their work remained free of interference.
"It is the judgement of the Working Group that environmental tobacco smoke is not a primary lung carcinogen," said Professor Idle, who is a smoker.
But Richard Peto, Imperial Cancer Research Fund professor of medical statistics said: "Cigarette smoke is such a potent cause of human cancer that it cannot be argued that passive smoking is harmless."
A spokeswoman for ASH (Action on Smoking and Health) said the report was "appalling". "This study is funded by the tobacco industry and therefore we're not surprised by these findings."Reuse content