Effectiveness of cycle helmets and the ethics of legislation

Replying to criticism of their arguments for compulsory helmet-wearing by cyclists (August 2004 JRSM1), Dr Cook and colleagues cite ‘well-conducted’ work from Canada2 concerning the effects of helmet-wearing on injury rates. The Canadian study does not in fact attempt this; rather it shows (and compares) injury rates in helmet legislating provinces and non-legislating provinces. Since there is no indication of what effect, if any, the laws had on helmet usage in the jurisdictions covered it cannot be assumed that, when the authorities legislate, helmet-wearing increases. In the province of Ontario, helmet usage was already very high at 65% among children before the law’s implementation.3 Since the law has not been enforced, any increase following the law would have been modest—although that would be difficult to verify since no province-wide surveys were conducted after the law came into effect on 1 October 1995. Also there were contradictions between the Canadian authors’ data and their conclusion. Robinson4 shows that for the two largest legislating provinces, Ontario and British Columbia (BC), the greatest decreases in head injuries did not occur in the years immediately after respective helmet laws came into effect but rather immediately before. That throws further doubt on the study method. The absence of enforcement of helmet laws explains the Canadian claim that the number of children riding bicycles does not decrease because of mandatory helmet legislation.5 Children seem to know intuitively when a doubtful adult discipline is foisted on them. It did not take long for children in Ontario to figure out that if the cops do not care about helmet laws then why should they. In contrast, British Columbia observed increases in helmet use following legislation,6 but that was coincident with aggressive enforcement and ticketing campaigns by local police (Personal communications with BC cyclists). The BC government did not feel the issue important enough to organize pre-law and post-law surveys to gauge the impact of its law on cycling levels. However, a 35% reduction in all reportable cycling accidents between the two complete years immediately before and after the law’s enforcement, 1995 and 1997,7 suggests considerable declines in cycling. Interestingly, head injuries in BC declined at a slower rate than the number of cycling accidents. Helmet campaigners uncritically latch on to any claim to push helmet agendas. Campaigners in the UK8 have already used the Canadian work in support of their arguments for legislation, including a claim that mandatory helmet legislation in Canada saved lives. The authors did not respond to my requests for substantiation of the latter claim; it may have originated from non-significant differences in the fatality data of Macpherson et al.2 An analysis of 28 years of Transport Canada’s traffic fatality data9 shows that the fatality trend for cyclists is virtually identical to the one for pedestrians. Thus it seems that other factors account for declining fatality and injury trends. Dubious claims on the efficacy of helmet legislation threaten the life-extending benefits of cycling and the gains being made from exercise in reducing heart disease, cancer and obesity.

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