The link between secondhand smoke and sudden infant death has been discredited in the last few years in scientific articles paid for and influenced by cigarette manufacturers, according to a new study of once-secret industry documents.
The key article, commissioned by Philip Morris and published in a respected pediatric epidemiology journal in 2001, discounts the significance of research showing a link between exposure to secondhand cigarette smoke and sudden infant death syndrome (SIDS). The article has been cited in at least 19 other scientific papers, misleading physicians, their patients and researchers about the risk of secondhand smoke exposure.
"Undermining people's understanding of the link between secondhand smoke and SIDS places infants everywhere at increased risk," according to Stanton Glantz, PhD, director of the Center for Tobacco Control Research and Education at UCSF and senior author of the new study analyzing the tobacco company documents.
Analysis of the Philip Morris documents shows that the company sought and paid an author to write an article for publication in a scientific journal, guided his writing and suggested changes in his conclusions in order to call into question the published studies showing links between secondhand cigarette smoke and SIDS.
The new report was prepared by researchers at UCSF and the U.S. Centers for Disease Control and Prevention (CDC) and appears in the March issue of the journal Pediatrics.
The article Philip Morris commissioned was part of the company's overall scientific strategic plan for addressing secondhand smoke (SHS) and childhood health issues, the documents show. One document summarized the "impact assessment" for this project as follows: "Should provide the necessary scientific background for a policy on the acceptability of smoking around children."
The key article acknowledges that smoking during pregnancy can endanger the fetus, but casts doubt on the published scientific finding that secondhand smoke increases the risk of sudden infant death -- a finding highlighted in 1992 by the U.S. Environmental Protection Agency and reinforced by the California Environmental Protection Agency in 1997.
The tobacco company carried out this disinformation campaign even after the landmark 1998 settlement between all of the major U.S. tobacco manufacturers and 46 states. In the settlement, the tobacco firms agreed to pay the states $206 billion over the first 25 years and continuing amounts after that, and agreed to stop creating controversy about the evidence linking smoking and disease.
The tobacco industry's disinformation campaign regarding secondhand smoke and maternal and child health can be counteracted, the UCSF and CDC researchers write in their analysis.
"Secondhand smoke must be recognized as an established, controllable risk factor for SIDS, like prone sleep positioning," they conclude. "Clinicians and public health officials should intensify their efforts to promote reducing infant exposure to secondhand smoke as an effective strategy for reducing SIDS."
The documents show that the tobacco industry hired scientists on at least two different occasions to prepare articles challenging the SHS/SIDS connection. The first one failed to attract an influential journal. But then Philip Morris retained a consultant to write a comprehensive review of all known risk factors for SIDS. Philip Morris was to provide the literature review, and the hired scientist was to write the paper. The company's documents show that Philip Morris budgeted $50,000 to $100,000 for this project.
The company's papers reveal a concerted effort by Philip Morris to influence the paper's content and conclusions. When the author completed his first draft, he sent it to the company for review. The original conclusion stated that secondhand smoke increased the risk of SIDS. But a Philip Morris scientific affairs executive questioned this conclusion. The author accommodated many of Philip Morris' suggested changes, and when he submitted his final draft to them, he had removed his original conclusion about the effect of secondhand smoke on infants. Instead, he wrote that "the majority of the effects of smoking can be explained by prenatal smoking by the mother," and that postnatal (infant) secondhand smoke effects were "less well established" than prenatal smoking.
As published, the article mentions the financial support of Philip Morris, but does not acknowledge that the article was initiated, reviewed and influenced by the tobacco company. Not only does the limited acknowledgement mask the extent of the tobacco company's influence on the conclusion, but totally hidden from view is the fact that the article was essentially conceived by the tobacco company in the first place, UCSF's Glantz points out.
"This study of Philip Morris activity since the tobacco industry signed the Master Settlement Agreement in 1998 shows that the industry continues to use its 50-year old strategies to sow confusion about the real dangers of secondhand smoke and to distort the entire scientific process," says Glantz.
The tobacco industry documents were made available as part of the Master Settlement Agreement, in which among other things, tobacco companies pledged to cease their efforts to discredit research on smoking and health. To this end, the current Philip Morris web site includes this statement:
"Public health officials have concluded that secondhand smoke from cigarettes causes disease, including lung cancer and heart disease, in non-smoking adults, as well as causes conditions in children such as asthma, respiratory infections, cough, wheeze, otitis media (middle ear infection) and sudden infant death syndrome. In addition, public health officials have concluded that secondhand smoke can exacerbate adult asthma and cause eye, throat and nasal irritation."
"The new study shows clearly that Philip Morris continues to orchestrate a behind-the scenes effort to undermine the credibility of the health warnings their web site acknowledges," Glantz says.
In their paper, he and his co-authors call into question the practice of accepting tobacco industry funds to support research.
"The tobacco industry's long and consistent history of manipulating the content and presentation of scientific results raises questions about publishing work funded by the tobacco industry," they write.
First author on the study is Elisa K. Tong, MD, a postdoctoral fellow in the UCSF Division of General Internal Medicine. Co-author is Lucinda England, MD, a medical epidemiologist in the Division of Reproductive Health at the CDC.