There are many good reasons to avoid secondhand smoke. It stinks. It lingers. It irritates. But contrary to popular wisdom and anti-tobacco propaganda, there is little solid evidence that it kills. Last week, a federal judge threw out a widely touted study by the Environmental Protection Agency that declared secondhand tobacco smoke a Class A carcinogen in 1993. The EPA report used dubious statistical methods to conclude that passive smoke causes 3,000 lung-cancer deaths per year. The ruling affirms what respected epidemiologists and biostatisticians have said for five years: EPA used political science, not sound science, to arrive at its ominous numbers.
U.S. District Judge William Osteen's harsh rebuke of the federal agency noted that EPA "publicly committed to a conclusion before research had begun" and "adjusted established procedure and scientific norms to validate the agency's public conclusions."
Very simply, the agency's procedure was verdict first, trial later.
Informed decision-making about risk is critical. Explaining how the agency clouded its findings helps enhance that understanding. The discredited EPA report was essentially a survey - or "meta-analysis" - of 11 American studies of spouses of smokers. By themselves, none of the 11 studies reported "statistically significant" associations between secondhand smoke and lung cancer. (Statistical significance is the scientific standard that separates negative health outcomes that can be expected by chance from more-convincing evidence that is likely to signal a true association.)
Extraordinary rejiggering was necessary to produce statistically significant results: When EPA couldn't meet the standard using traditional allowances for error, it simply lowered the accepted threshold to reach its desired conclusion.
This fudging drew criticism not just from the tobacco industry, but from independent analysts at the Congressional Research Service, Energy Department, UCLA, Yale and the University of Chicago.
Anti-tobacco activists are concerned the federal judge's ruling will lead to wholesale repeal of smoking bans nationwide. It won't and it shouldn't. Secondhand smoke is a proven nuisance, if not a health threat; the cultural tide has shifted irreversibly against it. And to be clear, the evidence of a causal link between direct smoking and lung cancer is solid and irrefutable.
Nevertheless, the unmasking of the EPA's statistical deception on the health effects of passive smoke should give anti-smoking activists pause. EPA Administrator Carol Browner was no doubt well-intentioned when she stated last week, "We believe the health threats to children and adults from breathing secondhand smoke are very real." But in a world where truth in science matters, believing is not enough.
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