Tuesday, January 16, 2007

CDC Defends Surgeon General's Statement that Brief Exposure to Secondhand Smoke Causes Lung Cancer

Rather than correcting the misrepresentation of science by the Surgeon General in his press release announcing the publication of the 2006 report on secondhand smoke, the Centers for Disease Control and Prevention (CDC) is apparently defending the Surgeon General's statement.

Here's the story:

In June 2006, the U.S. Surgeon General released a comprehensive report on the health effects of secondhand smoke which concluded that chronic exposure to tobacco smoke causes heart disease and lung cancer in nonsmokers.

However, in the press release accompanying the report, the Surgeon General claimed that: "Even brief exposure to secondhand smoke has immediate adverse effects on the cardiovascular system and increases risk for heart disease and lung cancer, the report says."

On June 28, I wrote on this blog that the Surgeon General had misrepresented the findings of the report, since the report mentioned nothing about brief secondhand smoke exposure causing heart disease and lung cancer. Further, I noted that the statement in the press release flies in the face of common medical sense, since we know that heart disease takes many years of exposure to develop, even in an active smoker. So how could a brief exposure to secondhand smoke cause heart disease in a nonsmoker?

Moreover, there is absolutely no scientific evidence that a brief exposure to secondhand smoke causes lung cancer in nonsmokers.

Sunday's feature article run by InsideBayArea.com highlighted my concerns: "Siegel's greatest concern with the tobacco control movement today is what he views as exaggerated assertions advanced by major public health organizations, including the U.S. Surgeon General's office, that fleeting exposure to secondhand smoke poses a serious public health threat. In June, the Surgeon General released an updated report on the dangers of secondhand smoke. A news release accompanying the report warned that "even brief exposure to secondhand smoke has immediate adverse effects" by increasing the odds of developing heart disease and lung cancer."

When confronted with my criticism of the Surgeon General's statement, the CDC apparently defended the statement: "The CDC's Pechacek also 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.'"

The CDC also apparently refused to explain what it meant by "brief" exposure: "The word "brief" is also left up to interpretation. 'We can't quantify what is 'brief,'' said Pechacek, who declined to state how long an interval qualifies as 'brief.'"

The Rest of the Story

This is a very important story, because to me, it is the first evidence that the Surgeon General's statement that brief secondhand smoke exposure causes heart disease and lung cancer was not merely a mistake, but was a conscious and intentional misrepresentation of the findings of the Surgeon General's report.

It truly appears that CDC is indeed defending the statement that brief secondhand smoke exposure causes lung cancer in nonsmokers.

And they are doing it based on the possibility that a small amount of exposure could potentially damage a single cell.

By this reasoning, any exposure to any carcinogen could be said to increase the risk of cancer. 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.

Using the CDC's reasoning here, all of its statements about the causation of cancer would become meaningless. 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. In fact, it really undermines your statements about carcinogenic exposures that truly are significant.

Moreover, CDC was apparently unwilling to define what it meant by "brief." Well if you can't define what you meant, then you shouldn't be making such a claim.

But most importantly, there is simply no evidence to support the Surgeon General's claim. There is no evidence that a brief exposure to secondhand smoke can cause lung cancer in a nonsmoker.

If you're going to make such a statement to the public, you have to be able to back it up with some evidence. And here, there simply is no evidence to support the claim.

In some ways, the claim could be a dangerous one, undermining the Surgeon General's warning about exposure to secondhand smoke. If people truly believe that even a brief exposure to secondhand smoke causes lung cancer, then why should they try to avoid or minimize their exposure to secondhand smoke? All of us have already been exposed to some secondhand smoke. If the cancer process has already been set in motion, then what point is there to minimize our exposure?

And the message to smokers is potentially more damaging. What incentive is there to quit smoking if a person could successfully quit, only to breathe in secondhand smoke for a few minutes and wind up with cancer anyway?

I would have felt much better if the CDC had simply acknowledged that the statement made by the Surgeon General was a mistake and that the truth is that it takes some degree of chronic exposure to secondhand smoke to develop heart disease or lung cancer. That would have been the responsible thing to do.

And it would have made it clear that the statement was simply a mistake.

But instead, we are left with the impression that the statement was not a mistake, but was an intentional expression of what the CDC believes is an adequately-supported scientific fact: that brief exposure to secondhand smoke does indeed cause heart disease and lung cancer. But since we know that it takes at least 20 years for even active smokers to develop heart disease, it is pretty clear that this statement is false.

Thus, it now becomes hard to avoid the conclusion that the Surgeon General is intentionally misrepresenting the findings of his own report to suggest to the public that brief exposure causes heart disease and lung cancer, when the report itself concludes, quite unmistakably, that chronic exposure to secondhand smoke causes heart disease and lung cancer.

The implications of this misrepresentation of science and the failure to correct a statement that is not only false, but absurd, on its face, is that not only is the credibility of the anti-smoking movement in question, but now the credibility of the Office of the Surgeon General, and even the CDC itself, comes into question.

Look - I've worked directly in the Office on Smoking and Health at CDC. I worked there for two years, and was partly responsible for many of the scientific statements that our office made. So I am the first to acknowledge that it is difficult work and that sometimes, you just make a mistake.

That's fine - I'm willing to give the Surgeon General's office and the CDC the complete benefit of the doubt and simply accept that the statement that brief secondhand smoke exposure can cause heart disease and lung cancer was merely an oversight.

The problem is that now - when confronted with the statement and given the opportunity to correct it - the CDC has apparently chosen instead to defend it. That is a problem, because now it becomes, at least in my view, a conscious and deliberate act not to correct the statement when you have the perfect opportunity to do so, but instead, are reported to be defending the statement.

I have certainly made my share of blunders. One of them was right here on this blog, when I made the false assumption that the failure of a journal article to report a conflict of interest of the authors was a fault of the authors. It turns out that the journal made a mistake in not printing the conflict of interest disclosure that was made. I immediately acknowledged this, corrected it, and apologized. And if anyone points out anything I've written that is in error, I'm committed to correcting it.

The reason is not only that I want to be accurate, but because my reputation as a credible source of information, analysis, and commentary on tobacco control issues is at stake. If, in one situation, I report errant information and don't correct it, then my readers will never really know whether what I'm reporting is accurate or not.

Well the same thing holds with our public health agencies. It may not seem like much to make one inaccurate statement in a press release, but if the agency loses its credibility as an accurate and responsible purveyor of scientific and health-related information, then its effectiveness in communicating important information and warnings to the public may be shot.

At some point, the crisis of credibility that I've been writing about in the tobacco control movement is going to cross the line over into public health itself. This is the first example we've seen of this, because although the office that handles much of the Surgeon General's communications is specifically devoted to tobacco control issues, it is also a part of the larger CDC, and thus is part of the public health establishment in general.

Isn't our credibility worth anything? Is it really worth risking everything just to avoid having to acknowledge that we made a mistake? Why do we in tobacco control seem physically unable to simply admit that we made a mistake? Why do we insist on defending claims that, on their face, are absurd?

I wish I understood the answers to these questions. Any help will be greatly appreciated.

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