Fear factor

We are being inundated with news about a killer virus that may be about to overwhelm humanity. Today, the World Health Organization raised the threat level to 5, one below pandemic level, so it was refreshing to see the St. Louis Post-Dispatch editorial “Fear factor” cautioning the public not to panic, noting the total laboratory-confirmed swine flu deaths to date as being only 8.

(As an aside: The U.S. government has proposed changing the name of the disease so that people don’t stop eating pork. Meanwhile, in Egypt the government is planning to slaughter the entire pig population based on dubious fears of contagion.)

The editorial went on to list total annual U.S. deaths from a variety of other common causes, including:

annual seasonal flu deaths: 36,000;
heart disease deaths for 2004: 652,486;
tobacco-related deaths: 438,000.

This reminds me just how easily the public and media can become obsessed with risks which may actually be small while ignoring major causes of premature death which are real but more familiar.

I think back to a story entitled “Killer Asteroids” by Harry Levins, former senior writer at the St. Louis Post-Dispatch, published on October 8, 1997. He posed the following question in the opening paragraph of his article:

Artist's impression of asteroid strike of the earth

Artist's impression of asteroid strike of the earth

“The odds of dying violently are greatest when the agent of violence is (choose one):

1. A tornado.
2. A flood.
3. An asteroid.

Answer: An asteroid.”

He went on to explain that two Air Force officers say that “we’re more likely to perish from an asteroid strike (1 chance in 25,000) than we are from a flood (1 in 30,000) or a tornado (1 in 60,000).” The officers suggest that we spend $122 million-a-year, averaged over 20 years, to combat this peril: a total of $2.44 billion.

Some other causes of premature death listed for comparison in the sidebar to the article:
Food poisoning: 1 in 3 million.
Fireworks Accident: 1 in 1 million.
Venomous Bite or Sting: 1 in 100,000
Airplane Accident: 1 in 20,000
Electrocution: 1 in 5,000
Firearms Accident: 1 in 2,500.
Fire: 1 in 800.
Murder: 1 in 300.
Car wreck: 1 in 100.

I posted the above on the web together with this discussion:

Harry Levins, who admits to enjoying a stogie now and again, failed to consider the dangers due to smoking, generally recognized as the number 1 avoidable cause of death in the U.S., so let’s correct that omission by figuring the risks from both active and involuntary smoking.

Using the same method of calculation as the Air Force officers, the lifetime chance of dying prematurely from each of these causes is respectively:

Smoking: 1 in 2.

Involuntary Smoking [“Secondhand smoke”]: 1 in 55.

In other words, smoking is like taking a double-barrelled shotgun with one barrel loaded, holding it to your head, and pulling the trigger during your smoking lifetime, and paying upwards of $30,000 or more for the privilege.

Premature death from involuntary smoking is about twice as likely as dying in a car wreck and six times as likely as being murdered. TV is full of mayhem caused by motor vehicles or handguns. When was the last time death from someone else’s tobacco smoke was portrayed or reported on TV?

HOW THE RISKS ARE CALCULATED:

Killer Asteroid. The two Air Force officers arrived at their 1 in 25,000 chance of a person being killed by an asteroid during their lifetime as follows:

The earth gets hit by an asteroid big enough to cause a global catastrophy once every 500,000 years, so the odds of that happening in any given year are 1 in 500,000. Assuming such an impact kills 25% of the Earth’s population, that makes the risk from an impact 1 in 4. The odds of any individual dying from an asteroid strike in any given year are 1 in 500,000 multiplied by 4, or 1 in 2 million.

But since we live on average 75 years, these odds must be multiplied by 75 to obtain the risk of premature death in any given year. Hence the lifetime odds of dying from an asteroid strike is 75 in 2 million, or 1 in 25,000.

Active Cigarette Smoking. For smokers, who number about 50 million adults, the number of deaths is estimated at over 400,000 each year, so the annual risk is about 400,000/50 million = 1 in 125. Since most smokers don’t start until they’re about 14 we should calculate the 75 year lifetime risk over 75-14 = 61 years.

So the lifetime risk is 61 x 400,000/50 million = 61/125 = 1 in 2.

Secondhand smoke. The total U.S. population was estimated as 266,499,365 on January 1, 1997, so the total number of nonsmokers is 266.5 million less 50 million = 216.5 million. The estimated number of deaths among nonsmokers each year due to involuntary smoking is 53,000 (1), so the lifetime risk of premature death = 75 x 53,000/216.5 million = 75/4,085 = 1 in 55.

(1) The figure of 53,000 was the best estimate available when the above calculation was made. The latest U.S. Surgeon General’s report on secondhand smoke (SHS), released in 2006, noted that in 2005 it was estimated that SHS kills more than 3,000 adult nonsmokers from lung cancer, and approximately 46,000 from coronary heart disease.

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