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Which is more of a threat to your health: Al Qaeda or the Department of Homeland Security?

An intriguing new study suggests the answer is not so clear-cut. Although it’s impossible to calculate the pain that terrorist attacks inflict on victims and society, when statisticians look at cold numbers, they have variously estimated the chances of the average person dying in America at the hands of international terrorists to be comparable to the risk of dying from eating peanuts, being struck by an asteroid or drowning in a toilet.

But worrying about terrorism could be taking a toll on the hearts of millions of Americans. The evidence, published last week in the Archives of General Psychiatry, comes from researchers who began tracking the health of a representative sample of more than 2,700 Americans before September 2001. After the attacks of Sept. 11, the scientists monitored people’s fears of terrorism over the next several years and found that the most fearful people were three to five times more likely than the rest to receive diagnoses of new cardiovascular ailments.

Almost all the people in the study lived outside New York or Washington and didn’t know any victims of the Sept. 11 attacks. But more than a 10th of them reported acute stress symptoms (like insomnia or nightmares) right after the attacks, and over the next three years more than 40 percent said they kept worrying about a terrorist attack affecting themselves or a family member.

Their worries were understandable, given the continual warnings from Washington. Officials repeatedly raised the color-coded level of the National Threat Advisory and sometimes explicitly warned of imminent attacks from terrorist cells supposedly operating in America. The alert level has never dropped below yellow (the third of the five levels). About a third to a half of Americans have continued to tell pollsters that they’re personally worried about being victims of a terrorist attack, and that an attack is somewhat or very likely within several months.

“It’s amazing how enduring these feelings of fear are, but look at what’s been going on,” said Alison Holman, a professor of nursing science at the University of California, Irvine, the lead author of the study. “I’d be surprised if those terrorist alerts didn’t contribute in some way to the ongoing worry about terrorism in our sample.”

Another of the authors, Roxane Cohen Silver, also at U.C. Irvine, is a psychologist who is on an advisory council to the Homeland Security Department.

“I’ve regularly pointed out to the department that there are psychological consequences to the raising of the alert,” Dr. Silver said. “Now we’re demonstrating that it may have physical consequences.”

The researchers caution that they’re not sure how serious the physical consequences are, because they’re relying on people reporting that their doctors have diagnosed new cardiovascular ailments. Also, studies like this show correlations, rather than an identifiable cause and effect. But since the researchers have taken into account reports of people’s health problems and anxiety that were collected before Sept. 11, and the levels of lifetime and continuing stress, they’re confident they’ve identified a worrisome increase in heart disease.

After controlling for various factors (age, obesity, smoking, other ailments and stressful life events), the researchers found that the people who were acutely stressed after the 9/11 attacks and continued to worry about terrorism — about 6 percent of the sample — were at least three times more likely than the others in the study to be given diagnoses of new heart problems.

If you extrapolate that percentage to the adult population of America, it works out to more than 10 million people. No one knows what fraction of them might consequently die of a stroke or heart attack — plenty of other factors affect heart disease — but if it were merely 0.0003 percent, that would be higher than the 9/11 death toll.

Of course, statistics of any sort, even when the numbers are rock solid, don’t mean much to people when they’re assessing threats. Risk researchers have found that even when people know the numbers, they’re less worried about death tolls than about how the deaths occur. They have good reasons — called “rival rationalities” — for fearing catastrophes that kill large numbers at once because these events affect the whole community and damage the social fabric.

But continual fear of terrorism is a strain on the social fabric, too. People become reluctant to even get together when public spaces are turned into fortified zones. Civil liberties erode and mistrust increases when the authorities keep warning of lurking terrorists and urging people to report “suspicious” activity, as in the ubiquitous advertisements in the New York subways exhorting people to call in tips to a counterterrorism hot line.

The sponsors of the New York campaign were so pleased with the results that they papered the subways with congratulations to the riders: “Last year, 1,944 New Yorkers saw something and said something.” But as William Neuman reported in The Times, the ads neglected to mention the number of terrorists arrested as a result of the tips: zero.

Meanwhile, how many subway riders were given diagnoses of new heart problems after riding to work every morning looking at ads reminding them that they might be blown to bits any second? Not zero, if you believe the new study.

Even before this study, some doctors were arguing that terrorism wasn’t nearly as dangerous as the related “epidemic of fear,” as Marc Siegel called it in a 2005 book, “False Alarm.” Dr. Siegel, of the New York University School of Medicine, pointed to studies linking fear of terrorism with increased risk of heart arrhythmias and elevated levels of an enzyme that correlates with heart disease.

“The fear response causes the heart to pump harder and faster, the nerves to fire more quickly,” Dr. Siegel said. “Excess triggering of this system of response causes the organs to wear down. For a person who is always on the alert, the result is a burned out body.”

It’s not fair to blame public officials alone for this fear epidemic. We in the news media have done our part to scare people. (More on how the “terrorism industry” distorts risks can be found at tierneylab.blogs.nytimes.com.) But since there hasn’t been an attack in America for six years, for domestic drama we’ve had to rely on dire predictions of politicians and security officials.

What if the alerts stopped? What if the security officials looked at this new medical evidence — or at their own perfect record of false alarms — and decided that the nation did not need to be in a perpetual state of yellow alert? What if they even decided that Americans could survive without any color at all?

I guess that’s a hopeless fantasy. No politician wants to be blamed for failing to anticipate a terrorist attack. No bureaucrats willingly abandon a system that keeps them employed.

But maybe these officials could be induced to take one more precaution. The next time they raise the threat level to orange or red, they could add, “Warning: Heeding this alert may be hazardous to your health.”

// posted by Alice @ Tuesday, January 15, 2008