UCLA smoking study criticized

By Edie Lau -- Bee Science Writer
Published 2:15 a.m. PDT Friday, May 16, 2003

A new UCLA study downplaying the effects of secondhand smoke on the health of smokers' spouses is being condemned even before it has appeared in print.

The research by epidemiologist James Enstrom examined the causes of death in nonsmokers with smoking spouses and concludes that exposure to secondhand smoke does not raise the risk of dying from coronary heart disease or lung cancer.

Funded in part by the tobacco industry and appearing in Saturday's edition of the peer-reviewed British Medical Journal, the study is directly contrary to the conclusions of many other scientists and research on the issue.

"As a piece of science, it's pretty crappy," said Stanton Glantz, a professor of medicine and director of the Center for Tobacco Control Research and Education at UC San Francisco.

The American Cancer Society, which built the database Enstrom used to do the analysis, issued a similarly sharp statement, saying Enstrom used the data inappropriately.

Critics said the chief flaw is that Enstrom's analysis assumes that nonsmokers with nonsmoking spouses were not significantly exposed to secondhand smoke. The problem, they say, is that when the study began in 1959, tobacco smoke was everywhere.

"He completely ignores the fact that in 1959, a little under half the population smoked," said Glantz, an authority on statistics and an outspoken anti-smoking activist. "So ... just walking around in your daily life, it was basically impossible to not breathe large quantities of secondhand smoke."

Enstrom, who collaborated on the research with Geoffrey Kabat, formerly of the State University of New York, Stony Brook, acknowledged that he couldn't rule out exposure to environmental smoke from other sources. However, he said that by surveying some of the subjects, he found that in general, nonsmokers who were not exposed to a spouse's smoke also tended not to be exposed much to other sources -- at least, according to their own perceptions.

The data upon which the analysis is based is somewhat convoluted. The original study, called Cancer Prevention Study I, was initiated nationwide by the American Cancer Society in 1959. More than 1 million subjects were followed until 1972. The findings contributed firm evidence that smoking tobacco is carcinogenic.

Enstrom said he picked up the database in the 1990s with the aim of following up on the causes of death in 118,094 Californians enrolled in the original study. He focused on 35,561 people who had never smoked and who had a spouse with known smoking habits.

To the subjects who were still alive and for whom he had an address, Enstrom in 1999 sent a new questionnaire that asked, among other things, whether they were regularly exposed to cigarette smoke from others in work or daily life. Their choices were "none," "light," or "moderate or heavy."

About 7,100 people responded. It was in their responses that Enstrom said he found an association between the subjects' exposure to secondhand smoke at home and outside the home.

For example, 61.7 percent of the women whose spouses never smoked reported having no regular exposure to cigarette smoke from others in work or daily life, whereas of those women married to current smokers, only 16.2 percent reported having no regular exposure to cigarette smoke from outside sources.

Enstrom could not explain why smoke exposure outside the home would match exposure inside the home, and he acknowledged that it might be difficult to summarize with one term -- none, light or moderate/heavy -- a lifetime's experience.

"I'm not saying I'm 100 percent right here," Enstrom said, "but there's enough (evidence to say that) this issue needs to be clarified, especially with coronary heart disease."

Enstrom's analysis found no greater incidence of death by coronary heart disease for the subjects with smoking spouses than among subjects with nonsmoking spouses. Current medical thinking says exposure to secondhand smoke increases the risk of heart disease by 30 percent.

The study looked only at causes of death and did not attempt to analyze in living subjects the prevalence of severe or chronic illnesses -- research which can be difficult and labor-intensive. It also did not attempt to address the effects of secondhand smoke on children. All subjects were adults when they enrolled in the study in 1959.

Dr. Clark W. Heath Jr., a former vice president for epidemiology and statistics at the American Cancer Society and now retired, was more circumspect than the society in his reaction to the study. He noted that many previous studies have had ambiguous results regarding secondhand smoke's dangers to adults.

"It's clearly a hazard to youngsters in terms of respiratory illnesses," said Heath, who spent the bulk of his career at the national Centers for Disease Control and Prevention.

"I think the overall conclusion at the present time is that environmental tobacco smoke is likely to contribute to increased cancer risk and probably coronary heart disease risk to people exposed. ... But there are a lot of studies on the books on that topic, so it's not an easy (question) to draw clear conclusions on."

Heath applauded Enstrom and Kabat's attempt to rejuvenate the long-term cancer study but cautioned against drawing firm conclusions.

William McCarthy, an epidemiologist and psychologist at UCLA, said Enstrom, whom he has known as a colleague for a decade, should have better underscored the study's limitations.

"I think the inferences drawn from it are not warranted," McCarthy said. "I thought he was a bona fide scientist as concerned with overstating any conclusions as I am, so this paper surprised me."

In addition to what they called scientific flaws, critics said Enstrom's use of tobacco-industry money further eroded the credibility of his research.

According to Enstrom, the research was funded in part by a $350,000 grant from the Center for Indoor Air Research, a now-defunct research organization that was funded by American tobacco companies.

Enstrom said he originally began doing smoking-related research with about $300,000 from the Tobacco-Related Disease Research Program, a UC organization funded by the state's Proposition 99 cigarette surtax.

He said he was denied further funding from the UC program and so decided to accept money from the tobacco industry's research organization.

"It was the only way (the work) could be done," he said, adding, "They've had no influence on the writing of this. They don't even know that it's coming out (in a journal), to my knowledge."

He added: "I'm staking my entire reputation on this, and I'm ready for the fallout."

Thomas Glynn, director of science and trends for the American Cancer Society, said he hoped the paper would not influence public perceptions about the safety of environmental cigarette smoke.

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