Health study 'discredited by secret tobacco plot'

The tobacco industry set out to discredit a landmark study linking passive smoking to cancer by commissioning rival research and then seeking to hide its involvement, a leading medical journal claims.

Documents found over years of legal action against cigarette manufacturers show that a coalition of companies agreed to fund or support a study downplaying the dangers of passive smoking. The project was designed to contradict a Japanese study in 1981 which concluded that the wives of heavy smokers faced double the risk of developing lung cancer as the spouses of non-smokers.

An investigation published today in the British Medical Journal claims that tobacco manufacturers were anxious that the research should have no obvious links to them.

Internal memos obtained by US researchers are alleged to show that the study, ostensibly to be carried out by Japanese scientists, was paid for by the world's biggest cigarette company, Philip Morris. The documents allegedly show how Philip Morris considered using an outside organisation funded by tobacco producers – the Centre of Indoor Air Research (CIAR) – as the official sponsor.

One memo from a senior Philip Morris executive in 1991 said CIAR could not directly fund the research but added: "There may be a reason to say it was sponsored by CIAR so as to 'hide' industry involvement. One may wish to use a CIAR cover for this project. I believe it is very important that this be done with all due haste."

There is no suggestion of impropriety by CIAR. According to the researchers, the records show that the project had the support of other cigarette giants, including British American Tobacco. One memo says that BAT's chief scientist, Chris Proctor, was to be the "behind-the-scenes" director of the study, which Philip Morris said would overturn the findings of the earlier Japanese research by Takeshi Hirayama.

The finished report concluded that there was no direct proof that second-hand cigarette smoke increased the risk of lung cancer and that the Hirayama study had "little scientific basis". Philip Morris also said Dr Proctor's role should remain unacknowledged in medical journals.

The BMJ article, written by two researchers at the University of California, concedes that the report, published in 1993 under the name of a UK-based consultant for the tobacco industry, acknowledged backing from tobacco firms. The consultant, who received $5,000 in fees, was suggested as the author by Dr Proctor only after the initial draft named the Japanese scientists as authors.

Philip Morris said the documents used in the BMJ article were genuine but said it had been engaged in a legitimate scientific exercise to test the Hirayama study. A spokesman said: "This was a valid exercise at the time." A BAT spokesperson said it had made public its role in the study. "The published report stated unequivocally that there had been financial support from tobacco companies."