The CDC seems to be simultaneously defending and backing away from its warnings that a few errant molecules of secondhand smoke just might give you heart disease or lung cancer. Last summer, in a statement that accompanied his report on secondhand smoke, then-Surgeon General Richard Carmona claimed "even brief exposure…increases risk for heart disease and lung cancer." Responding to criticism that such statements are scientifically unfounded and biologically absurd, since these diseases take decades to develop even in smokers, Terry Pechacek, associate director for science at the CDC's Office on Smoking and Health, recently told Inside Bay Area "we can't quantify what is 'brief.'" Could it be, say, 40 years? Pechacek won't say. At the same, Pechacek "explained the reason for the Surgeon General's warning that even brief exposure could trigger cancer. 'There is some risk that even a very small amount can damage a cell,' he said, setting off a chain reaction that causes cancer.'"
This position renders irrelevant any attempt to determine what level of exposure to a possibly dangerous chemical is associated with a measurable increase in cancer risk. It implies that any substance that causes cancer in some doses under some circumstances should not be tolerated in any dose under any circumstances. Michael Siegel sums it up well on his tobacco policy blog:
By this reasoning, the CDC should also be warning the public that:
• A single chest X-ray causes cancer.
• Being in the sun for thirty seconds causes cancer.
• Breathing in diesel fumes for ten seconds causes cancer.
• Eating peanut butter causes cancer.
• Eating a single char-broiled burger causes cancer.
• Drinking a sip of chlorinated water causes cancer.
In fact, just the process of living every day could be said to cause cancer, since there is always damage being done to our cells that could potentially trigger cancer. The body has defense mechanisms that repair this damage constantly. This is the reason why it takes more than a single exposure to cause cancer. The exposure has to overwhelm the body's ability to repair the damage….Once you are willing to state that a single exposure to a carcinogen that could potentially damage one cell is enough to warrant a public statement that the exposure causes cancer, then all of your statements about carcinogenic exposures become meaningless.