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|Second-hand Smoke Study Sparks Controversy
By Mike Wendling
CNSNews.com London Bureau Chief
May 16, 2003
London (CNSNews.com) - A study about to be published in this week's British Medical Journal indicates that second-hand smoke doesn't increase the risk of heart disease or lung cancer, but the publication and the study's authors have come under attack by anti-smoking groups.
Two American researchers analyzed data from an American Cancer Society survey that followed more than 118,000 Californians from 1960 until 1998.
James E. Enstrom, of the University of California at Los Angeles and Geoffrey C. Kabat of the State University of New York at Stony Brook concluded that "the results do not support a causal relation between environmental tobacco smoke (second-hand smoke) and tobacco related mortality, although they do not rule out a small effect."
"The association between exposure to environmental tobacco smoke and coronary heart disease and lung cancer may be considerably weaker than generally believed," the researchers wrote.
The study was roundly condemned by anti-smoking groups including the American Cancer Society and even by the British Medical Journal's parent organization, the British Medical Association. They said the researchers received money from the tobacco industry, a statement that was confirmed by the journal Friday.
The American Cancer Society (ACS) pointed out what it called several flaws in the research. The researchers based their study on a small subset of the original data, the ACS said, and because of the greater prevalence of smokers in the 60s and 70s, "virtually everyone was exposed to environmental tobacco smoke."
Smoking opponents also pointed out in the original study, although the health of the subjects were monitored until 1998, no information on smoking habits was collected after 1972.
"We are appalled that the tobacco industry has succeeded in giving visibility to a study with so many problems," Michael J. Thun, ACS national vice president of epidemiology and surveillance research, said in a statement.
"The American Cancer Society welcomes thoughtful, independent peer review of our data. But this study is neither reliable nor independent," Thun said.
Other studies have indicated that inhaling second-hand smoke on a regular basis increases the risk of heart disease by about 30 percent. But as the researchers pointed out in their BMJ article, exposure to second-hand smoke is difficult to measure and such studies necessarily rely on self-reported data that may or may not be accurate.
Figures are skewed, researchers said, by former smokers who are wrongly classified.
"The relation between tobacco-related diseases and environmental tobacco smoke may be influenced by misclassification of some smokers as never smokers," the researchers wrote.
However, several British groups agreed with the ACS assessment of the study. The British Medical Association said that 1,000 people die every year in the U.K. as a result of passive smoking.
"There is overwhelming evidence, built up over decades, that passive smoking causes lung cancer and heart disease, as well as triggering asthma attacks," said Vivienne Nathanson, BMA's head of science and ethics. "In children, passive smoking increases the risk of pneumonia, bronchitis, and reduces lung growth, as well as both causing and worsening asthma."
A spokesman for Action on Smoking and Health said: "We are utterly surprised as to why the BMJ has published this. It's nothing but a lobbying tool."
"This is just one study," the spokesman said. "It will do nothing to change the massive body of evidence that has built up over the years."
The journal stood by its decision to publish research but editors turned down interview requests Friday. A spokeswoman said decisions on publication were made only after "careful consideration and peer review."
The study, which was available online and will be published in the BMJ on Saturday, was partially funded by money from the tobacco industry, the spokeswoman said, but could not provide further details.
Groups campaigning against further tobacco regulations in Britain welcomed the research. Smokers' lobby group FOREST said the "jury is still out" on the effects of second-hand smoke.
"This is typical of the anti-smoking lobby's bullying tactics," said FOREST director Simon Clark. "They attack not just the authors but the messenger ... the BMJ is one of the most respected journals in the world."
Attacks on the study in the U.K. have been led by proponents of a total ban on smoking in public places like pubs, clubs and restaurants, a position that Clark said was undermined by the study.
"People who want to ban smoking in public places use passive smoking as their number one argument," he said. "That's why this study is so significant."