JANUARY 24, 2005
Home, Sweet Home?
Last year researchers at San Diego State University and the University of Colorado, targeting a forgotten front in homeland security, decided to study soap scum. “Over time, vinyl shower curtains accumulate . . . lush microbial biofilms,” they reported. The films contain Sphingomonas spp. and Methylobacterium spp., opportunistic pathogens that can lead to serious blood and urinary-tract infections. Although the scum is thought to threaten only people with weakened immune systems, biologist Scott Kelley nonetheless advises caution. “I clean my shower curtain more frequently now and change it much more regularly,” he told the San Diego Union-Tribune.
Finishing my shower, I step carefully around the dripping vinyl. In my journal, I ranked being at home as the safest part of my life, but David Ropeik, the director of risk communication at the Center for Risk Analysis, disagrees. “Home isn’t as sweet as we think,” he tells me.
Consider my morning routine by the numbers. An estimated 280,190 toilet, shower and bathtub accidents sent victims to the emergency room in 2002, according to Injury Facts, a gripping statistical compendium published annually by the National Safety Council. (This article cites the latest available U.S. data unless otherwise indicated.) I shave with a razor (an implement linked to 33,532 injuries) with hot water (involved in 42,077 injuries) at the sink (23,283 injuries). For breakfast, I slice a grapefruit with a knife (441,250 injuries) and pour juice into a glass (86,909 injuries). Before sitting down to eat, I jog down two flights of stairs to fetch the newspaper. Easy, champ. Falls are a significant danger, causing about 28 percent of the 30,000 accidental home deaths6 each year (poisoning and fires are the other top killers).
Depressing stuff. “If you were a fanatical risk analyst and started to work through all of the risks you’re facing, you’d be immobilized,” says Paul Slovic, a professor of psychology at the University of Oregon. “You’d probably end up staying in bed all day.” That, sadly, wouldn’t be a good idea either. Every year, around 400 people unintentionally suffocate or strangle themselves in bed.
As a risk-pro-in-training, though, I’m learning to pause for consideration before becoming alarmed about anything. The U.S. population numbers nearly 300 million, so the chance of any one of these accidents happening to me is remote. What’s more, home hazards aren’t equal-opportunity. Fatal falls, for instance, are 70 times as likely when you’re 75 or older as when you’re 44 or younger. Still, domestic risk isn’t insignificant. In 2003, one in 37 people was disabled for a day or more by an injury at home; according to Injury Facts, disabling injuries are more numerous in the home than in the workplace and in car crashes combined.
The headlines in the paper are grim, and I take a deep breath and sigh. Oops, bad idea. In later risk research, I learn that exposure to air pollution is estimated to be 10 to 50 times as high indoors as it is outdoors7; most of us spend the majority of our time inside, where poor ventilation allows pollutants to accumulate. A partial list of the toxins that might be in my lungs this morning: carbon monoxide, nitrogen dioxide and gases from household products; mold, mites, mildew and dander; traces of lead, asbestos, pesticides, arsenic, flame retardant and product packaging. Yuck.
The danger posed by some pollutants is well understood. For example, radon gas—invisible, odorless and radioactive, seeping up naturally from the ground into homes—has been identified as the number-two cause of lung cancer in the U.S.8 For many other pollutants, though, scientists simply aren’t sure of the health effects. More than 75,000 chemicals are employed in U.S. industry and agriculture. So far, the Centers for Disease Control and Prevention’s National Biomonitoring Program has tested peoples’ bodies for the presence of just 157 of them.
An emerging area of concern is synthetically produced nanoparticles, which some scientists theorize might be dangerous because of their ability to accumulate in the body and penetrate cell membranes. Last year, Eva Oberdrster, a researcher at Southern Methodist University, placed buckyballs—a type of carbon nanoparticle being studied for use in drugs, computers and fuel cells—in a fish tank at a concentration of 0.5 part per million. (One of the first consumer products to use buckyballs is, of all things, a crack- and chip-resistant bowling ball.) Though preliminary, Oberdâ€rster’s results were troubling: Within two days, the nine largemouth bass in the tank had all developed brain damage. It’s far too early to draw any conclusions about a human health hazard, however, so what to make of nanoparticles? My risk-educated attitude is to place uncertain dangers like this one on a mental watch list. I’m not going to lose any sleep over buckyballs—not yet—but I will stay alert for more hard science.
JANUARY 25, 2005
Where the Streets Are Insane
It’s midday, and, feeling sluggish in my home office, I step out to pick up a soda. The nearest deli is just down the street, across the X-shaped intersection of Lafayette and Fulton. This is a loathsome spot, crowded with some of the world’s worst drivers. Speeding minivans run red lights. Lincoln Town Cars make unsignaled rights, oblivious to pedestrians. Buses blaze past, inches from the curb. Ever since our first week in the neighborhood, Anne and I have called this the Intersection of Death.
In 2003, an estimated 80,000 pedestrians were injured and 5,600 were killed by cars. For men in my 25-to-34-year-old age bracket (I’m 34), the annual death rate is 5.5 per 100,000 people, which doesn’t seem too high. (By comparison, car accidents, the leading cause of death for men my age, kill at a rate of 26 per 100,000.) The risk experts later advise me, however, that statistical averages only hint at my personal danger level. Consider that New York streets are far busier than average and that New Yorkers spend more time walking than typical Americans do. Also, I’m an incorrigible jaywalker. You can get your soda faster if you beeline across the Intersection of Death.9
In the diary, I rate jaywalking as I did snow-biking—as a significant but manageable danger. Again I’m guilty of making a common perceptual error: Studies show that people significantly underrate everyday risks and overrate new ones. When the first cases of mad cow disease appeared in Germany, 85 percent of people polled thought the disease was a serious threat. Mad cow was a much bigger problem in the U.K., but it had been around awhile; in polls conducted there at the same time, only 40 percent of the public indicated serious concern.
Anne never jaywalks across the Intersection of Death.10 Studies have consistently concluded that women, on average, are considerably more apprehensive about risk than men are. The theories as to why this is so run along predictable sociobiological lines: Women bear and nurture children and are therefore instinctively protective of life, etc.
It turns out, though, that risk-assessment differences aren’t just a man-woman thing. In a 1994 study, James Flynn of Decision Research in Eugene, Oregon, found that the gender difference in risk ranking was attributable to roughly 30 percent of his subject pool’s white males, who ranked all risks as being very low. Members of this subgroup tended to be better-educated, wealthier and more politically conservative than the rest of the pool. Inoculated by success in life, they were less pervious to worry and expressed optimism about their own—and society’s—ability to deal with danger.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.