Mandatory bicycle helmet laws could do more harm than good, a new study claims.
Helmet laws like those in effect in Australia levy a substantial cost on healthcare systems because savings from fewer head injuries pale in comparison to the costs incurred by decreases in cycling, a mathematical model concludes.
, a mathematician at Macquarie University in Sydney, Australia, estimates that bicycle helmet laws would cost the US $4.8 billion per year, Netherlands $1.9 billion, and the U.K $0.4 billion.
Advertisement
However, one critic contends that de Jong鈥檚 methods overestimate the health benefits of cycling, as well as the drop in cyclists caused by helmet laws.
鈥淭here鈥檚 a lot of uncertainty around it,鈥� de Jong admits. 鈥淚 try to reconcile all these various numbers or proportions that impinge on the question of whether helmet laws are very useful.鈥�
He concludes that only under extreme, theoretical circumstances do mandatory helmet laws not end up costing the healthcare system. Head injuries must be a substantial proportion of bicycling injuries, few riders must abandon their bikes due to helmet laws, and the health benefits of cycling need to be low.
鈥淓ven under very favourable assumptions to the pro-helmet lobby group, it鈥檚 very hard to get a benefit,鈥� de Jong says.
Numbers debate
Precise numbers on the costs and benefits of cycling and the use of helmets are hard to come by and often contentious.
One 1989 case-controlled study concluded that bicycle helmets reduce the risk of head injury by 85 per cent. But de Jong says those results are overstated.
Writing in the in 2006, , a statistician at the Department of Primary Industries in Armidale, Australia, claimed that helmet laws caused bike ridership decreases of 20 to 40 per cent in several Australian cities and states.
鈥淲hat she has never shown to my satisfaction, or that of other critics of her work, is how long the decline persisted,鈥� says , an epidemiologist at Montreal Children鈥檚 Hospital in Canada.
In an attempt to circumvent all of this uncertainty, de Jong created a model that can be adjusted by putting in various values for drops in cycling rates due to helmet laws, the cost of an accident due to not wearing a helmet, and the overall health benefit of cycling.
鈥淓verybody takes one piece of the evidence and nobody is really putting in all the pieces of the puzzle,鈥� he says.
Heart benefits
Under most parameters, de Jong鈥檚 model concluded helmet laws would come with a net health cost. Exactly what cost is hard to determine. To come up with a figure of $4.8 billion for the US, he assumed the health benefit of cycling was a generous $1 per kilometre. However, as long as the benefit of cycling is not zero, there will be a net cost incurred due to helmet laws, he says.
Pless, though, contends that de Jong鈥檚 model overvalues the health benefits of recreational cycling. Most riders travel short distances rather slowly, blunting some of cycling鈥檚 cardiovascular benefits. He points to a study of 9000 UK government employees which found that people between the ages of 45 and 64 needed to pedal 40 kilometres per week to see any reduction in heart disease rates.
Despite these issues, de Jong hopes policy makers will take a good look at his paper before supporting legislation mandating helmet use.
However de Jong, a native of bike-loving Holland, makes clear that he would not discourage people from wearing helmets. 鈥淚 go to Holland and places like that, and I don鈥檛 wear a helmet,鈥� he says. 鈥淚 used to live in London, and I wore a helmet all the time.鈥�
Journal reference:
