> An excellent place to look to information about this stuff is battlefield
> injuries: the rise of, and increasing sophistication of, helmets by soldiers
> has completely changed the nature of the number and scope of injuries in
> battle over the last century.
That's great for the battlefield, but we're not talking about shrapnel here.
> Other people -- like construction workers and fire fighters -- don't wear
> helmets because they are tools; they wear them because the risk of head
> injury in what they do is significant, and they work. Head injuries are
> typically the most avoidable injury there is.
That's the bare bodkin: whether the risk of head injury is significant, or more to the point, significantly greater than other risks. Speaking again from memory, supposedly at some point the Swedish government looked into the risk of head injuries from cycling in deciding whether to institute a mandatory helmet law, and found that it was comperable to that of car passengers. In a fit of consistency, they considered making them mandatory for car use. The last I heard was that fatalities-per-mile on bikes in the US is comparable to that of cars (injuries of any type are more difficult to guage since bike injuries are less likely to be reported).
I think somebody already touched on this, but medical organizations typically oppose mandatory helmet laws, in part because of the potential of laws to reduce cycling, and the wages of sedentary lifestyles have been much greater collectively than that of head trauma. The attention on helmet use detracts from a firmly established fact that the health benefits of cycling significantly outweigh the risks, helmet or no. Less firmly established, I think, is that a concern for safety keeps people off bikes. That is independent of whether there are circumstances when bicycle helmets clearly provide protection: we have no major argument there. But you can say the same of wearing body armor and a Kevlar helmet on the mean sidewalks of a US city.
-- Andy