The latest Surgeon General’s Report on the health consequences of environmental tobacco smoke (ETS) — and a publication from the Centers for Disease Control (CDC) that accompanies it — need their own warning label: “Contains mix of facts, speculation, and downright hyperbole.”
–The publications correctly note that secondhand smoke can be a public health hazard: children are particularly vulnerable. Parental smoking increases the risk of sudden infant death syndrome and middle-ear diseases including acute and recurrent otitis media and chronic middle-ear effusion. ETS can trigger asthma, coughing, and breathlessness in exposed kids and can retard lung growth and pulmonary function. There is evidence in adults that it can cause nasal irritation (not to mention be intensely annoying).
–The SG report is on target in that it systematically dismisses (or says there is insufficient evidence) for many of the oft-claimed hazards of ETS (although that part of the report received no media coverage): for example, there is, according to the SG, no established causal relationship between ETS and breast or cervical cancer, congenital malformations, behavioral development, or childhood cancers.
–The most significant and questionable conclusion of both reports is that ETS causes lung cancer and cardiovascular disease in nonsmokers. The SG argues that ETS increases a nonsmoker’s risk of heart disease by 30%, causing 46,000 premature deaths annually. Similarly, ETS allegedly increases the risk of lung cancer 20-30%, causing 3,000 premature deaths from this cause.
But unlike the link between ETS and acute effects such as childhood ear infections, the link to chronic disease is far more tenuous. Most studies of the effects of ETS are based on observation of disease frequency in spouses of cigarette smokers. Where elevated risks of lung cancer are observed, the elevations are relatively small — and are the result of high-dose, long-term exposures. The estimated degree of increased risk needs to be put in perspective. While one might think that a 30% increased risk translates into a person having a one in three chance of developing the disease, this is not the case at all. A 30% increase in lung cancer in a nonsmoker refers to increasing a risk that is very low to start with to a risk slightly higher. Using the 30% risk estimate to predict number of deaths due to ETS is supposition on top of speculation.
By contrast, a regular cigarette smoker increases his or her risk of lung cancer by over l,000% — and estimates that over 400,000 Americans die of “first-hand” smoking are derived from sound, epidemiological comparisons of disease occurrence in smokers as compared to nonsmokers. Now, having said that, the existing data do strongly suggest that living for years with a smoker and breathing in the inhaled smoke is not good for you — and may indeed increase your risk of both lung cancer and heart disease.
That brings us to the most important concepts of all: dose and length of exposure. Both the Surgeon General’s and the CDC report completely omit any reference to these critical variables. The CDC motto here is “It hurts you; it doesn’t take much; it doesn’t take long,” and they note that “even a little (ETS) can be dangerous.” The SG goes even further, with this totally outrageous statement: “the scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke.” This leaves us with the clear impression that if we merely walk through a smoke-filled room, we have put our health in irreversible jeopardy.
These statements violate the basic tenet of toxicology: “only the dose makes the poison.” What is most alarming here is that the top doctor in the land is communicating a message that anything that is harmful at high dose can be lethal at low dose — when that is simply not true.
Just in case they have not hyped the threat of ETS enough, the CDC in its report grimly warns us that ETS is “toxic.” In a shameful ploy to cash in on prevailing consumer chemophobia, the agency informs us that cigarette smoke contains ammonia, toluene, cadmium, arsenic, and formaldehyde, which they “helpfully” tell us are used, respectively, in household cleaners, paint thinners, batteries, pesticides, and embalming fluid — as if this exotic list alone were evidence that the chemicals are dangerous.
All of us interested in public health should be striving to reduce the toll of cigarette smoking. With so many valid reasons not to smoke and not to be exposed to ETS, why overstate the case and thereby lose credibility? Scare tactics, exaggeration, and political correctness do not make good public policy. When the CDC and the Surgeon General were preparing their report, it appears that smoke got in their eyes.