Macpherson AK, Parkin PC, To TM. Injury Prevention 2001;7:228-230
|see also: Errors and omissions in Canadian research group's bicycle helmet papers|
A mandatory helmet law for children was enacted in Ontario in October 1995. The study set out to examine trends in children's cycling rates before and after legislation in one health district (East York). Child cyclists were counted at 111 preselected sites in the late spring and summer of 1993 - 97 and in 1999.
Although the number of child cyclists per hour was significantly different in different years, the authors say that these differences could not be attributed to helmet legislation. In 1996, the year after the law came into effect, average cycling levels were higher than in 1995, the year before legislation (6.84 v 4.33 cyclists per hour).
The authors therefore conclude that, contrary to the findings in Australia, the introduction of helmet legislation did not have a significant negative impact on child cycling in this community.
A letter pointing out serious shortcomings in the paper, together with the original authors' reply, was subsequently published in Injury Prevention. (Robinson, 2003)
Although the only paper producing such a result, and despite contradictory evidence from Australia, New Zealand and other jurisdictions where helmet laws have been introduced (BHRF, 1020), this paper is often cited as evidence that helmet laws do not discourage cycling.
Principal criticisms include:
The lack of comprehensive data reported in this paper (especially with regard to helmet wearing rates) masks many of the above points. The paper would have been clearer and more valuable had the authors presented all the relevant data.
Other criticisms include:
This paper presents figures for the number of child cyclists observed at different types of locations (schools, parks, residential streets and major intersections). The counts of child cyclists, and whether they wore a helmet or not, were taken at 111 survey points within the Borough of East York, a suburb near to Toronto, Canada, in the late spring and summer between 1990 and 2001. Helmet legislation (affecting under-18's only) came into effect in October 1995. Because of the early onset of winter in Toronto, and its prolonged nature, the legislation would not have had much effect until the spring of 1996 (if it was going to have an effect at all).
A major weakness of the study is that only data on the number of child cyclists are presented. Helmet wearing data are not presented. This is a critical point, because in Canada under-16s cannot be charged with a traffic offence. Rather, it is their parents who are subject to charges for failing to ensure their children are complying with the law. This makes it hard for the police to enforce a child helmet law, except on those in the 16-17 age band. In theory, a police officer could accompany a child home and charge the parents, but in practice this was never done. The Toronto Metropolitan Police never issued any tickets for violation of the child helmet law (Macpherson, 2004). Helmet use did increase for a short period after the introduction of the law, then declined back to pre-law levels, once it became clear that the police were not going to pursue any significant level of enforcement.
A further weakness of the study is that cyclist count data from the years 1990-1992 are not available either in this paper or any other, although the data are known to have been gathered. Hence it is not clear what level of cycling there was prior to helmet promotion.
The development of helmet wearing rates over time has been published separately (#190#). The chart below brings together the two data sets to observe whether there is a link between helmet use and child cyclist counts.
Child cyclists in Ontario
(helmet law effective from 1996)
Note: apparently no data were sampled in 1998 or 2000
Helmet use had already been high for some years before the law came into effect, and the law did not increase wearing rates greatly.
"Cyclist per hour" data are too limited to draw conclusions. Weather variation from year to year will have affected counts, but hours of sunshine are not presented. It is not clear, in available data, whether the number of child cyclists was affected by pre-law helmet campaigns. The promotion was clearly forceful to achieve such a high wearing rate (almost 50%) in only four years. In the UK, helmet use by child cyclists is only about 17% (Sharratt, Walter and Anjurn, 2009), despite more than 20 years of promotion. Government research has nonetheless observed declines in children cycling where promotional campaigns have run (BHRF, 1080). This experience has been seen in other countries following helmet promotion, even in countries with a prominent cycling culture, such as Denmark (BHRF, 1020). It is thus very likely that the strong promotion of helmets in East York also reduced cycling in the years before 1993.
Extending the foregoing point, the data do suggest that child cycling was in decline in the immediate pre-law period, even after growth in helmet use had stopped.
The data also strongly suggest that when helmet use fell post-law, due to lack of enforcement, there was a recovery in cycling.
In view of these criticisms, the paper is not a full and fair summary of the events that took place and the authors' conclusions are not valid.
The data suggest that cycling had already been deterred by helmet promotion in the years before the law was introduced. The large increase in cycling after 1998 was accompanied by helmet use dropping back to pre-law levels. Neither of these important outcomes is evident in this paper, since the authors do not publish helmet wearing rates.
A later paper by the same authors reported that the percentage of head injuries to children had declined after enactment of the Ontario law and that therefore the law had been beneficial (Macpherson et al, 2002).
However, re-analysis of the data (Robinson, 2003b) showed that head injuries had started falling well before the law. Indeed, the greatest annual reduction had taken place 2 years before the law was enacted. After the law, the reduction in % head injuries was not significantly different to the situation in other Canadian provinces where cycle helmets were not mandatory. This suggests that trends, rather than helmet legislation, may have been responsible for the changes in head injuries. This would not be surprising if the law had no significant lasting effect on either helmet or cycle use.
Macpherson AK, To TM, Macarthur C, Chipman ML, Wright JG, Parkin PC, 2002. Impact of Mandatory Helmet Legislation on Bicycle-Related Head Injuries in Children: A Population-Based Study. Pediatrics 2002; 110(5):e60.
Communication concerning unpublished research by Dr A. Macpherson et al, School of Kinesiology and Health Science, York University, Toronto, Ontario, and M J Wardlaw in April 2004. .
Parkin PC, Khambalia A, Macarthur C, 2003. Influence of socioeconomic status on the effectiveness of bicycle helmet legislation for children: a prospective observational study. Pediatrics 2003;112:e192-e196.
Robinson DL, 2003. Helmet laws and cycle use. Injury Prevention 2003;9:380-381.
Robinson DL, 2003. Confusing trends with the effect of helmet laws. Pediatrics P3R 7 Jul 2003.
Sharratt C, Walter L, Anjum O, 2009. Cycle helmet wearing in 2008. Transport Research Laboratory PPR420.