Are helmets safe?

From an interesting article in the British Medical Journal:

"The statistical wrangle over the effectiveness of helmets is actually a side issue; what we need people in authority to understand is that cycle helmets inevitably damage public health. Even for cyclists on Britain's roads, the health benefits exceed the risks by a factor of 20. The health benefits of cycling are so great---and the health injuries from driving so great---that not cycling is really dangerous. By telling people that they need helmets for an activity that for a century has been regarded as "safe"---and in fact has a fine safety record---you inevitably engender the impression that cycling must have become more dangerous than driving and walking. That deters cycling. That reduces cyclists' presence on the roads. That increases the risk of death. And if wild claims about helmets saving lives are published in the media, helmet users are bound to feel overly secure, thus compromising their one vital safety feature---a sense of caution. In addition, over time most people--- and especially parents---will come to believe that it is wearing a helmet that matters, not acquiring skilful technique. These effects have been noted in every country where helmets have come into general use, including the United Kingdom. Millions will die early because they did not cycle. "