The NY Times had a nice article on the trend away from bicycle helmet promotions. There are, of course, the usual anecdotal “how a helmet saved my life” stories, to which the author had a great reply:
Before you hit the comment button and tell me that you know someone whose life was probably saved by a bike helmet, I know someone, too. I also know someone who believes his life was saved by getting a blood test for prostate specific antigen, detecting prostate cancer. But is that sense of salvation actually justified, for the individual or society?
He is referring to recent studies which suggest PSA testing does more harm than good. That is not a bad analogy. Like the PSA test, helmet protections may seem good in lab tests, but the real world data says they do more harm than good.
Or to put another way: if the FDA were to regulate helmets as a medical device (and why not, given the supposed public health benefits), then it is unlikely the FDA would ever grant regulatory approval.