'No Safe Level of Secondhand Smoke'?


Here is my USA Today "Opposing View" on the surgeon general's secondhand smoke report. They have titled it "The Science Is Not In," which is odd because my main points were:

1) The science probably will never be "in," if that means conclusive proof that long-term exposure to secondhand smoke causes lung cancer and heart disease, because low-level risks are very hard to confirm in epidemiological studies.

2) The science is irrelevant to the policy question of whether the government should dictate smoking rules on private property.

The USA Today editorial asserts that "only smoke-free environments prevent risk." Today's New York Times likewise claims the surgeon general's report concluded "there is no safe level of secondhand smoke," a position that contradicts the basic toxicological principle that the dose makes the poison. Since it is difficult even to measure the health consequences of long-term, relatively intense exposure to secondhand smoke among people living with smokers for decades, how could one possibly demonstrate an effect from, say, a few molecules? It's clear that the vast majority of people exposed to secondhand smoke suffer no noticeable injury, so in what sense is their exposure unsafe? "No safe level" is an article of faith, not a scientific statement.

In any case, contrary to what he Times and various other news outlets are saying, this assertion does not seem to appear in the surgeon general's report. The closest thing I could find was this discussion of respiratory hazards from Chapter 2:

The evidence for underlying mechanisms of respiratory injury from exposure to secondhand smoke suggests that a safe level of exposure may not exist, thus implying that any exposure carries some risk. For infants, children, and adults with asthma or with more sensitive respiratory systems, even very brief exposures to secondhand smoke can trigger intense bronchopulmonary responses that could be life threatening in the most susceptible individuals.

As far as I can tell, there is no blanket statement that any amount of tobacco smoke is inevitably harmful. In any case, as Mark Wernimont notes at Clearing the Air, the Occupational Safety and Health Administration does set acceptable levels for the chemicals in tobacco smoke. Wernimont cites several studies of real-world concentrations in environments where smoking is permitted, including one by the American Cancer Society, that found levels well below the OSHA limits. As I noted in my book For Your Own Good: The Anti-Smoking Crusade and the Tyranny of Public Health, two studies using personal air monitors conducted in the 1990s found that nonsmokers with the heaviest exposure to secondhand smoke were absorbing between 0.8 and 1.5 milligrams of "tar" a day. By comparison, a single regular Marlboro has an official (machine-measured) tar yield of 12 milligrams.