Row over passive smoking effect

A study suggesting the damaging effect of passive smoking on health may have been overstated has sparked a furious row.

The study, funded in part by the tobacco industry and published in the British Medical Journal, concludes that the link between environmental tobacco smoke and coronary heart disease and lung cancer may be considerably weaker than generally believed.

However, the American Cancer Society, whose data was used, has expressed serious misgivings about the conclusions.

And anti-smoking campaigners have condemned the the research as "biased" and "unreliable".

The researchers, James Enstrom of the University of California and Geoffrey Kabat of New Rochelle in New York, analysed data on 118,000 people who took part in a 40-year cancer prevention study in California.

In particular, they focused on 35,500 people who had never smoked, but who had a spouse who did.

The researchers found exposure to environmental tobacco smoke was not significantly associated with death from coronary heart disease or lung cancer.

A spokesman for the American Cancer Society told the BBC the research was "inaccurate and unreliable".

But, as expected, active cigarette smoking was confirmed as a strong risk factor for coronary heart disease, lung cancer, and chronic obstructive pulmonary disease.

The researchers say their findings suggest estimates that passive smoking may increase the risk of coronary heart disease by as much as 30% are probably inaccurate.

However, they do accept that a small effect cannot be ruled out.

"This could be very damaging as it will be used by industry lobbyists to argue against laws to ban smoking in public places and workplaces "

Amanda Sandford, Action for Smoking and Health

He said the last time the society checked to see whether the people who took part in the study were still smoking was 1972.

So, it was possible that many people had kicked the habit at any time during the last 26 years of the study, which finished in 1998.

And those who did continue to smoke may well puff on a cigarette outside their house away from their spouse.

Biased research

The UK anti-smoking charity Action on Smoking and Health condemned the BMJ for publishing a "biased" piece of research.

Research manager Amanda Sandford said the authors of the study appeared to be deliberately downplaying the findings to suit the tobacco industry.

She said: "Questions will inevitably be asked about the decision to publish research conducted by scientists in the pay of the tobacco industry.