Tuesday, September 05, 2006

Newest Fallacious Claim: Passive Smokers Breathe in More Nicotine than Smokers

According to a press release issued by the Massachusetts Department of Public Health (MDPH) last week: "Non-smokers, especially children, who are exposed to secondhand smoke can inhale up to seven times the amount of nicotine inhaled by a smoker."

This press release accompanied a new report showing that nicotine yields of cigarettes increased by approximately 10% from 1998-2004.

Presumably, the reason why this claim was made was to attempt to demonstrate that the report's findings have implications not just for smokers but for nonsmokers as well. By suggesting that nonsmokers inhale much higher amounts of nicotine than smokers, the press release is implying that the increase in nicotine yields is likely to be harming the health of nonsmokers in addition to smokers.

The press release highlights a number of adverse health effects of nicotine among smokers, including the following:
  • "Increased levels of nicotine may make it more difficult for the average smoker to quit.
  • Increased levels of nicotine consumed by pregnant women can lead to developmental delays in childhood as well as low birth weight infants.
  • Nicotine changes the way that insulin works in the body. Smoking raises blood sugar levels, placing smokers at higher risk for developing diabetes and making it harder for those who already have diabetes to control blood sugar levels.
  • Medications that treat depression and other mental illnesses can lose their effectiveness when combined with nicotine."
It is following these adverse health effects of nicotine among smokers that the press release informs the public that nonsmokers may inhale seven times the amount of nicotine as smokers. Thus, it appears this claim was made in order to make the public think that the increased nicotine yields of cigarettes over the past 7 years are resulting in an adverse health impact on nonsmokers as well as smokers.

The Rest of the Story

Assume that a nonsmoker spends 12 hours a day in the most heavily polluted smoke-filled room imaginable: an enclosed smoking lounge. Based on research I published, the level of nicotine in such a lounge is about 70 ug/m3 (micrograms per cubic meter). These are about the most extreme assumptions one could make about the concentration and duration of a nonsmoker's exposure to secondhand smoke.

Assuming a respiration rate of 1.2 m3/hr (cubic meters per hour), the nonsmoker will inhale 70 x 1.2 x 12, or 1008 ug (micrograms) of nicotine during that day.

Based on the MDPH report, a smoker inhales 1.9 mg, or 1900 ug (micrograms) of nicotine per cigarette.

Thus, the most heavily exposed nonsmoker, under the most extreme conditions, will inhale the same amount of nicotine as a smoker who smokes 1008/1900, or 0.53 cigarettes a day.

In order for the above health claim to be true, the smoker would have to smoke 0.53/7, or 0.076 cigarettes per day.

In other words, in order for it to be true that nonsmokers inhale 7 times the nicotine as smokers, even under the most extreme secondhand smoke exposure conditions, a smoker would have to only smoke one-tenth of a cigarette per day.

In still other words, the claim is mathematically impossible. If a nonsmoker inhales 7 times the nicotine as a smoker during a day, then that smoker is lying about his or her smoking behavior.

Under reasonably high exposure conditions (let's say a nonsmoking bar worker who is exposed for 8 hours to a nicotine concentration of 30 ug/m3), the nicotine intake of that nonsmoker will be 288 ug of nicotine, or 0.15 cigarette equivalents. In other words, in a relatively high exposure situation, the nicotine exposure of a nonsmoker is about 130 times less than that of a 1 pack per day cigarette smoker.

It is important to recognize that the relevant health claim is not merely an exaggeration or an overstatement. It is simply false.

What troubles me the most is not that the claim is false. Anyone can make a mistake and report inaccurate information. What troubles me is that the claim was apparently being made with a specific purpose: to try to convince people that the increasing nicotine yields of cigarettes has implications for the health not only of smokers, but of nonsmokers as well.

As I've already argued, it is not even clear to me that increasing nicotine yields have produced adverse health effects among smokers, because there is no documentation that overall nicotine intake has increased. It may be that just as smokers compensate for reduced nicotine delivery by increasing their consumption and smoking/puffing intensity, they may also compensate for increased nicotine delivery by reducing their consumption and smoking/puffing intensity.

But to argue that the increased nicotine yields of cigarettes has an implication for the health of nonsmokers is really pushing it too far. And as it turns out, it requires a fallacious health claim to support such an assertion.

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