Laws Based on Lies?
Enough with the "she's not wearing a helmet" blather, already.
“65% of statistics are just made up.” — unknown
It’s been repeated so many times as to be considered a “fact.” But this “fact,” which has been used to justify mandatory helmet laws across the nation and around the world, is based on a misleading report about a poorly designed study. I’m speaking of course about the “fact” that bicycle helmets reduce head injury risk by 88%. This paper does a great job of explaining the errors in the infamous Thompson, Rivara & Thompson study, published in New England Journal of Medicine in 1989. The key shortcomings:
- The “cases” (bicycle head injury hospital admissions) were significantly different in character from the “control group” population.
- None of the cases involved bicyclist crashes involving motor vehicles.
- The report is claimed to apply to all ages, but the case and control groups were all children.
- Helmet use was “self selected.” Non-head injuries were less severe among helmet-wearers than non-helmet-wearers, implying that helmet-wearers are less likely to get involved in more serious collisions.
According to the Florida Department of Health, there were 622 traumatic brain injuries (TBI) among bicyclists in Florida in 2005. By comparison, during the same period, 14,696 automobile and truck passengers, 1,643 motorcyclists, and 1,189 pedestrians suffered traumatic brain injuries. Cyclists were only 3% of all traffic-related TBIs. The TBI rates per 100,000 population* (2005 thru 2007) are: motor vehicle occupant 82.5, motorcycle 10.7, pedestrian 7.1, bicyclist 3.7. (That’s total population, not “cycling population” or “motorcyclist population,” etc.)
[The above paragraph has been updated with better data. The previous numbers were from a report that evidently only included injuries recorded in the state's "Central Registry."]
Since helmet use is such an important element of the “dangerization” of cycling, we owe it to ourselves to do what we can to smack down those ubiquitous “88%” claims whenever we can.
Obligatory Disclaimer: I am not anti-helmet. I wear one most times I ride. I am anti-helmet law because there is some evidence that such laws reduce cycling (especially among kids) and because there is no evidence of a compelling state interest.
Posted in Bicycles & Equipment, Safety
29. December 2009 at 10:46 am :
Mighk: if you don’t think that helmets give you some kind of protection, why wear one at all? Since you wear one most of the time, you must think it does some good — don’t you? Aren’t you sending out the message of “dangerization” any time you wear one?
Also — you didn’t mention children and helmets. Are your feelings about anti-helmet laws applicable to children as well?
AndrewP (being the devil’s advocate) …..
29. December 2009 at 12:17 pm :
They clearly do offer some protection — IF they are worn correctly (a big problem I see with kids) — but does that justify a state law?
I don’t think the state’s purpose (in respect to helmets) should be to “make bicycling safer,” it should be to reduce traumatic brain injuries, since they have such a large impact on individuals, their families, and the state as a whole. If your goal is to reduce transportation-based TMI, you go after the largest cause, which is automobile use.
Just as I wrote for the vest question at CommuteOrlando, I don’t believe wearing safety equipment per se is “dangerization.” Dangerization comes when we insist that others do as we do (or as we want them to do).
But there are some instances when a mandate of some sort makes sense. I think, for example, that bike clubs are wise to insist that members wear helmets while on club rides. Why? Because club riders quite often get tangled up with one another and sometimes go down hard. (I’ve seen more cracked helmets during club rides than any other situation.) Making your fellow club members deal with a TMI along the side of the road is really unfair.
As for children, I have seen the focus shift over the years to helmets instead of good cycling skills and practices. Instead of “here’s how to ride and here’s where you’re permitted to ride” (limiting the child to streets appropriate to his/her skills and judgment), all today’s parents (and teachers) know to do is say “wear your helmet and stay in the cul de sac.” And we wonder why kids don’t bike anymore.
There has been an 85% drop in child cycling injuries involving motor vehicles since 1990 in metro Orlando. While one might say that’s a good thing, it’s not due to better cycling behavior, better motorist behavior, or helmets (head injuries are about 5% of cycling injuries); it’s because kids are not riding any more. The steepest section of the decline in those injuries was when the Florida legislature was debating and passing the helmet law and the first couple years after passage. Correlation does not prove cause, of course. Perhaps there were other factors as well.
29. December 2009 at 2:08 pm :
What Thompson, Rivara & Thompson asked, essentially, was “how many brain injuries might be mitigated through the use of bicycle helmets?” A better question is “what are the best strategies for mitigating cycling brain injuries?” The first question is more likely to be asked by someone who already assumes helmets are the best answer.
That better, second question leads you to ask, “which cycling behaviors and situations are most likely to contribute to brain injuries?” And then, “how do you mitigate for those behaviors and situations?”
29. December 2009 at 2:10 pm :
OK. And I agree with almost all you wrote. I wear a helmet as an optional piece of equipment like I might wear, say, knee pads if I was skateboarding. I do not want this mandated by State law …..
I think it would be interesting to discuss further what the role of the State should be in matters like this (not just this particular issue). What is their desire goal? Should it be accomplised via laws, education, or other means? Should the State not get involved in matters that almost exclusively effect the individual and not others or society at large?
Good questions to ponder …….
29. December 2009 at 2:21 pm :
Of course, that’s one of the most contentious arguments in politics: which behaviors should be mandated by law (wearing seat belts? wearing motorcycle helmets? pedestrian helmets anyone?) and which should only be encouraged?
If government is going to get fully into the risk management business, then the first thing to do, traffic safety-wise, is probably to ban motorcycles, since that form of travel is so much riskier that all the others. No, what we and our elected officials prefer to ask is, “How do we make _____ safer?”
Like the Seattle helmet researchers, our legislators have started with the assumption that helmets are one of the best strategies for safer cycling, then asked whether or not the state has a legitimate interest in mandating their use.
7. January 2010 at 12:52 am :
The big issue here is not the political argument about helmet wearing, but whether the Rivera et al. study claiming such a high degree of effectiveness in helmet wearing is valid. In my cycling classes, I no longer cite it.
One should never base public policy on single study, especially one with potential major flaws. Sure, if there is a magic bullet and it actually serves the public interest (TMI costs up to hundreds of thousands of dollars, often public dollars, per incident), we should implement it. Assuming, of course, there are not competing losses exceeding the benefits (dangerization).
Further, the implication that the authors have such a vested interest in the truth of their study and in implementing helmet wearing casts some doubt on their objectivity. The point of science is to be skeptical, not to be a true believer.
I wear one because I figure it may protect me against a lot of potential low speed crashes without significant downside costs. But if I crash heavily on a fast descent in the mountains above Los Alamos a la Fabio Casartelli, a helmet will probably be irrelevant. That’s life. And death, I suppose.
7. January 2010 at 12:56 am :
“TBI”, i.e. Traumatic Brain Injury, not TMI. Sorry. Thinking too much about nuke stuff these days…
8. January 2010 at 11:10 am :
TMI … TBI …
You were just repeating MY mistake Khal; I had TMI everywhere!
I’ve corrected it.
Too Much Information!
1. June 2010 at 4:35 pm :
I’m sold on bicycle helmets. I don’t care about statistics and debates. The issue is, for me, a matter of personal experience.
Years ago, I was accelerating down a long hill on a state highway when a beat-up old car passed me. Someone in the car stood up through the sunroof, shouted something indistinct, and threw a full can of beer at my head. The impact against the side of my helmet and my own startled reaction almost made me crash.
The can dented my helmet a quarter-inch deep, right through the outer shell and into the styrofoam underneath. That beer can would have split my head open for sure.
This happened more than 15 years ago. I always cycle with a helmet now. I figure, if my helmet prevents a head injury, saves my life, or preserves my dignity, even once during a lifetime of cycling, it’s worth it.