Wednesday, December 14, 2005

Stretching the Science to Promote Policy: Are We Perhaps Going Too Far?

In reviewing the fact sheets put out by SmokeFreeOhio to support campaigns to promote smoke-free workplaces (including bars and restaurants) in Ohio, I came across a number of examples where I think the science of secondhand smoke was presented in an inaccurate, unsubstantiated, or undocumented way - in other words, in which the science was, in myopinion, being stretched to try to support smoke-free laws.

This post outlines these examples and considers the issue of whether this type of stretching of the science is appropriate and justified in order to promote smoke-free laws.

Here are the prime examples:

1. "Five minutes of exposure [to secondhand smoke] stiffens the aorta as much as smoking a cigarette, making the heart work harder to pump blood. Only 30 minutes of secondhand smoke exposure can cause narrowing of blood vessels, restricting the flow of blood and contributing to hardening of the arteries. In that same 30 minutes, changes to your blood boost your risk of building up fat deposits that could lead to heart attacks and strokes. After 120 minutes of exposure, your heart rate variability is reduced, increasing the chance of an irregular heart beat that can itself be fatal or trigger a heart attack."

2. "After twenty minutes of exposure to secondhand smoke, a nonsmoker'’s blood platelets become as sticky as a smoker'’s, reducing the ability of the heart to pump and putting a nonsmoker at an elevated risk of heart attack."

3. "Very small amounts of exposure can trigger a fatal heart attack."

4. "Secondhand smoke can cause the debilitating disease pulmonary emphysema, causing severe damage to the walls of the air sacs, with the lungs eventually losing their capacity to expand and contract."

5. "Secondhand smoke exposure increases the risk of stroke. The more secondhand smoke an individual is exposed to, the greater the risk of stroke."

6. "Working in a smoker-friendly office" for 8 hours is "comparable to smoking" 6 cigarettes.

7. "A study of emergency room patients in Helena, Montana, found that their 100% Clean Indoor Air Law reduced the city'’s rate of heart attacks by 40%."

8. "Adolescents exposed to secondhand smoke are more likely to have metabolic syndrome--—a group of conditions such as high blood pressure, high cholesterol and high blood sugar, increasing the risk of heart disease, stroke and diabetes."

9. "Bartenders are up to 6 times more likely to die from lung cancer than people who work in smoke-free businesses."

The Rest of the Story

1. Five minutes of exposure: I think it is quite misleading to suggest that just 5 minutes of exposure to secondhand smoke causes any clinically meaningful "stiffening" of the aorta. It is misleading, as well, to suggest that 30 minutes of secondhand smoke exposure can cause any clinically meaningful narrowing of blood vessels, and that it could boost your risk of having a heart attack or stroke. And it is equally misleading, I think, to suggest that 2 hours of exposure to secondhand smoke represents any meaningful risk of triggering a fatal cardiac arrhythmia or heart attack, under all but the most extreme of circumstances.

The thing that the public needs to understand about acute exposure is that it causes cardiovascular changes that, if repeated over a long period of time, can lead to heart disease. But the idea that a 5 minute, 30 minute, or 2 hour exposure to secondhand smoke increases one's risk of heart disease substantially is, I think, misleading.

The scientific evidence linking secondhand smoke to heart disease relates to the effects of chronic exposure. There is no evidence I am aware of (and I have reviewed the studies cited in the SmokeFreeOhio fact sheets) that acute exposure to secondhand smoke causes any meaningful increase in the risk of heart attack, arrhythmia or death (again, in all but the most extreme circumstances). To suggest otherwise is, I think, scientifically disingenuous, but more importantly, I think it may cause unnecessary anxiety among those who are exposed to secondhand smoke.

This fact sheet is basically telling people (who are not epidemiologists or physicians so they have limited ability to critically evaluate the claims) that if they are exposed to secondhand smoke for a short period of time, they may suffer stiffening of the aorta, hardening of the arteries, cardiac arrhythmias, and sudden and fatal heart attacks. This is simply not true. And there is no reason for people to have such a concern about a short-term exposure. Chronic exposure is, in my opinion, a legitimate concern, but to suggest that you may drop dead because of an acute exposure to secondhand smoke is, I think, ridiculous and irresponsible.

2. Twenty minutes of exposure: While there may be some increased risk to persons with existing severe heart disease who are exposed acutely to secondhand smoke, I do not think it is reasonable to suggest that 20 minutes of exposure to secondhand smoke generally increases a nonsmoker's risk of having a heart attack. I don't think that the bulk of the population needs to worry about walking into an environment where smoking is taking place and suffering a heart attack 20 minutes later. But this is precisely what this fact sheet seems to me to be suggesting.

3. Fatal heart attack: The suggestion that in general, very small exposures to secondhand smoke can trigger a fatal heart attack is, I think, blatantly misleading. I am not aware of any evidence that this is true, and even among people with existing heart disease, while there is some suggestion that there can be some coronary compromise with acute exposure (and therefore patients are advised to avoid any exposure), I still am not aware that the risk of a fatal heart attack from "very small exposures" is substantial. But clearly, it is wrong to suggest that in general, very small exposures can trigger a fatal heart attack. And I think this is an irresponsible claim, because I don't think people who have very small exposure to secondhand smoke should be concerned that they may suddenly drop dead of a heart attack.

4. Debilitating disease pulmonary emphysema: The scientific evidence simply does not support a conclusion that secondhand smoke exposure causes emphysema. This claim is in direct conflict with the conclusions of the California EPA report on secondhand smoke, which concluded that: "ETS exposure may play a role in the genesis of chronic respiratory symptoms and produce small, but measurable, decrements in pulmonary function." In other words, while secondhand smoke exposure may produce some chronic respiratory symptoms, at most it results in a mild decrement in pulmonary function; it most certainly does not cause the debilitating disease pulmonary emphysema, and people exposed to secondhand smoke should not be worried that they are going to come down with emphysema and debilitating lung disease, as this fact sheet suggests.

5. Risk of stroke: The claim that secondhand smoke causes stroke is, I think, premature. And so does the California EPA, which concluded that: "Further investigation is warranted to clearly elucidate the role of ETS exposure in stroke."

6. Comparable to smoking 6 cigarettes: The problem here is that the comparison to the amount of active smoking that is equivalent to passive smoking in a particular setting is specific to a certain smoke constituent. In other words, the cigarette equivalents of passive smoking are different for nicotine, benzene, NDMA, benzo(a)pyrene, etc. If you don't specify what constituent you are talking about, then the comparison is essentially meaningless. The fact sheet does not mention what specific constituent it is talking about; thus, the statistic presented has little meaning.

7. Helena: I have already beaten this issue to death. I won't say anything further here, except that I think it is premature to claim that smoking bans will result in a 40% decline in heart attacks.

8. Metabolic syndrome: I have already pointed out why I think that this one particular study cited in the fact sheet does not, in fact, provide any meaningful evidence that secondhand smoke exposure causes metabolic syndrome. I think it is far too premature to suggest such a conclusion.

9. Six times more likely to die: I don't think the claim that bartenders are up to 6 times more likely to die from lung cancer is substantiated. This is an area I know a lot about, since it is an area in which I have conducted a fair amount of research. My own published estimate was that bar and restaurant workers are 1.5 to 2 times more likely to die from lung cancer due to their secondhand smoke exposure. The California Occupational Mortality Study revealed that bartenders have 2.4 times the risk of lung cancer compared to all other occupations, but the risk dropped to 1.5 after controlling for active smoking. I think a reasonable estimate would be that bartenders are 1.5 times, or at most, 2 times more likely to die from lung cancer. Six times more likely? I don't believe that's a reasonable estimate.


First, to understand where I'm coming from, I support smoke-free bar and restaurant laws and I have generated much of the science that supports these policies. Much of my research has been devoted to the health effects of secondhand smoke exposure, especially for bar and restaurant workers, and I have actively worked to support smoke-free bar and restaurant laws in a number of towns, cities, and states. I have worked closely with a large number of smoke-free coalitions to produce fact sheets on this issue in support of such laws. So I support the overall goals of SmokeFreeOhio.

Nevertheless, my conclusion that there are so many inaccuracies and misleading representations of the science in the fact sheets put out by SmokeFreeOhio in support of their smoke-free campaigns is concerning to me.

My impression is that these fact sheets are stretching the science in order to try to provide added support for smoke-free laws. And while I support such laws, I don't condone the inaccurate representation of science in order to promote these laws.

I think stretching the science is wrong for two major reasons.

First, I believe that scientific accuracy and integrity are values in and of themselves.

Second, I believe that if we start to stretch the science too far, and the public catches wind of it, we are going to risk losing our credibility. Because the public cannot discern what we are stretching and what we are reporting accurately. If the public begins to realize that we are stretching the science in some areas, what is to prevent them from thinking we are stretching it in areas where we are really reporting quite accurately?

In other words, while advocates may think that stretching the science serves to enhance their mission of promoting smoke-free workplaces, in the long run, I think it may impair our ability to get these laws passed, because it is going to hurt our credibility. And our credibility may be our most prized possession. There aren't many more important strengths that I can think of for a public health organization or movement.

Honestly - I'm really not trying to nitpick here and overly critique these fact sheets. I realize that they are written by advocates, and not necessarily by scientists. Nevertheless, there does come a point where I think it begins to do a disservice to the public to convey so many misleading ideas, especially ones which may cause undue anxiety among people who, for whatever reason, are exposed acutely to secondhand smoke.

And my impression is (and it's just my impression - I can't prove or document this) that this tactic of stretching the science is something that is relatively new. I simply don't remember this kind of "scientific stretching" when I was involved more actively with promoting smoke-free laws in the 1990s. I do remember spending hours with many advocacy groups going over their fact sheets with a fine tooth comb to make sure that we weren't making any claims that could not be substantiated.

My impression is that something has changed - and the movement now supports an environment in which stretching the science seems acceptable and advocacy groups no longer take the kind of care that they did in the past to ensure the accuracy and substantiation of their public claims.

So to answer my own question: YES - I do think that perhaps we are going too far in stretching the science. And it's for no good reason. It doesn't matter whether breathing secondhand smoke for a few minutes is going to cause people to keel over and die from a heart attack. In my mind, you don't have to make such a claim to provide support for protecting workers from a health hazard.

YES - when we start suggesting to the public that very small exposures to secondhand smoke are going to cause them to drop dead of heart attacks, that secondhand smoke is going to cause the debilitating lung disease emphysema, and that a half hour of exposure to secondhand smoke is going to contribute to hardening of the arteries, then I think we are going too far in stretching the science to support our agenda.

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