Thomas Rice was a bit nonplused by all the fuss generated by a paper he published last year in the Emergency Medical Journal on the increased risk of car crash fatality due to obesity.
“We had quite a little media frenzy,” says Rice, a research epidemiologist with UC Berkeley’s Safe Transportation and Research Center. “I was surprised.”
But weight, after all, is right up there with sex and money as topic of obsessive interest, guilt and shame—and touchiness. The study, co-authored with Motao Zhu of the Injury Control Research Center at the University of West Virginia, determined that obese drivers are almost 80 percent more likely to die in a car crash than people with more moderate Body Mass Indices (BMIs).
Still, all news has a cycle, and the study soon dropped from the public ken. But now it’s back, because of the dummies. Humanetics Innovative Solutions, a Michigan-based firm that manufactures the safety test devices, has announced its development of an “obese” crash test dummy.
Humanetics CEO and President Christopher O’Connor says his company had been considering the development of a heavyweight dummy for some time, but that the study by Rice and Zhu made the project a priority.
“When you have data confirming that you’re 78 percent more likely to die in an accident if you’re obese, that’s a major problem,” says O’Connor. “The last strongly regulated [crash test dummies] came out in the 1980s, when 15 percent of the U.S. population was obese. Now it’s more than a third, and 40 percent of middle-aged people are obese. The size of the average adult driver has changed dramatically, and we have to address that change in our products.”
Until now, continues O’Connor, adult crash tests involved a “rather slender” dummy weighing 169 pounds. “It represented a BMI of a little less than 25, which means it’s no longer relevant. We took the data [from Rice and Zhu] that showed people with a BMI of 35 are 51 percent more likely to die in a crash, and used that as our baseline.”
The new dummy is truly magisterial in its dimensions, with a 35 BMI and a weight of 273 pounds. But Humanetics didn’t just slap on lipid analogue material to an existing design and call it big-boned.
“People don’t gain weight uniformly from head-to-toe,” O’Connor says. “We had to mimic the way extra weight is distributed on a human body. As it turns out, most of the gain is in the midsection.”
And that seems to be the primary reason for the increased fatality rates among the obese, says Rice. In basic terms, a big belly makes it difficult if not impossible to adjust seat belts properly.
“For maximum safety, a seat belt should be anchored as close and tight to the pelvis as possible,” Rice says. “But obese people tend to position the belt around their bellies. That means the belt is perhaps six inches further from the pelvis than it would be with a person of normal weight. So in a crash, an obese person will travel an extra six inches before the belt stops him. That extra six inches can result in contact with a dashboard, windshield or steering wheel at high momentum.”
Rice observes that ailments that commonly affect the obese such as diabetes and heart disease may also play a role in the higher fatality rates, but that the study doesn’t address such “co-morbidity” factors. That, he says, will require additional research.
The new dummies could help regulators and auto companies refine safety systems to better address the needs of the overweight. But is that the right track? Should the infrastructure change to accommodate a trend that has negative implications for public health, or should more money and effort go into reducing obesity rates?
“It is extremely difficult to get people to take weight off and keep it off,” responds Rice. “In the U.S., obesity rates have plateaued at about 30 percent of the population. It’s an issue that’s not going away anytime soon. So the best approach may be reconsidering the design of restraint systems.”
In any event, obese crash test dummies seem a rational response to existing realities. And the dummies will change in other ways, says O’Connor. They’re not going to just get heavier; they’re going to get “older.”
“We’re working on an ‘elderly’ dummy,” he says, adding that he hopes to offer it later this year. “After 60 or 70, injury rates go up dramatically. Plus, the injuries are different than those for younger people. For example, the elderly can suffer organ damage at higher rates. So we’re addressing those physiological changes.”
Indeed, crash test dummy tech is evolving rapidly. O’Connor cites his company’s newly released advanced model: Thor. “It has many more sensors than earlier models, produces many more channels of data, and provides truly biofidelic responses. It allows you to hone in on the precise degree of injury. Not just that a certain kind of crash in a specific vehicle injures your ribs, for example, but whether it’s the second or third rib, and whether it’s a bruise or a fracture.”
Still it all gets down to the fact that the country is getting older and fatter. And more vulnerable to injury. That hardly warrants a happy face emoticon, and O’Connor doesn’t attempt to put a cheery spin on it. Still, “at the end of the day, we just want to make sure everyone is as safe as possible,” he says. “We shouldn’t think these problems are restricted to the U.S. Obesity rates in China and India are growing faster than in this country. These are safety issues that are global in scope, and we have to deal with them.”
