Secondhand Smoke Study Raises Ire
Study Shows No Association Between Passive Smoke and Health Risks; Others Criticize Research
"ACS scientists and in particular, myself, had repeatedly asked him not to use the data to study the effects of secondhand smoke because it would lead to unreliable results," Michael Thun, MD, head of epidemiological research for the ACS, tells WebMD. "And it did."
Thun says the study, co-authored by Geoffrey Kabat, PhD, of the State University of New York at Stony Brook, is flawed for several reasons:
- There's no information on smoking habits after 1972, even though the observation period went another 26 years. "We don't know if the nonsmokers continued to be exposed to secondhand smoke, or if their spouses continued to smoke," Thun tells WebMD.
- Since the participants were an average of age 52 when the study began in 1959, many smoking spouses could have died, quit smoking, or ended the marriage before 1972, when Enstrom started his observation phase. This would have affected the secondhand smoke exposure of the nonsmokers. In addition, environmental factors such as secondhand smoke are less apparent in older ages.
- Participants were first enrolled in 1959, when secondhand smoke was pervasive. "Most people were exposed to it, pretty much everywhere, whether or not they were married to smokers."
- The finding is based on only 10% of the original study participants.
- The tobacco industry funded the study as part of an ongoing campaign to publish studies that question the dangers of secondhand smoke. "It views secondhand smoke as one of the most dangerous components against it, since it's what causes cities and states to restrict public smoking," says Thun. "And it actively seeks out this kind of research to confuse the public."
In fact, researchers reported in the Journal of the American Medical Association in 1998 that 75% of studies done between 1980 and 1995 that found no link between secondhand smoke and health problems were funded by tobacco companies. In that review, researchers examined 106 studies conducted in those 15 years; two in three indicated secondhand smoke does contribute to lung and heart disease.
"While this study is flawed, there are at least 50 very reputable studies that find a link between secondhand smoke and lung cancer and at least 50 others that find an increased risk of heart disease," says Thun.