Bicycle helmets and the law
BMJ 2013; 346 doi: https://doi.org/10.1136/bmj.f3817 (Published 12 June 2013) Cite this as: BMJ 2013;346:f3817All rapid responses
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It is amazing that helmets are supported with such a passion that the poor turban, worn by Sikhs in this country, lawfullly and as an alternative to a helmet, has been ignored by epidemiologists.
It was suggested by yours truly (J Roy Soc Med 2005, February; 98(2):86) that the merits of this turban should be studied. There is a considerable population of fully fledged Sikhs (as opposed to the Sehjdhari Sikhs who do not subscribe to the full five requirements of the Khalsa). These Sikhs with a bulky turban, tightly wound and with the long hair collected in a bun on top of the head inside would appear on the face of it, to be protected to some extent from head injury.
Whether the somewhat shorter and less loose turban worn in Khyber and beyond would be effective at all, is doubtful.
As a start, would the epidemiologists like to study head injury data of Sikh cyclists vs non-Sikh cyclists?
Competing interests: No competing interests
One recent study of the effect of legislation for Australia considered a range of issues, including cycling levels, fatalities, injuries, health and enforcement (ref 1). A negative cost benefit ratio was reported:
‘Cost benefit ratio is (0.408 x 20)/(0.25 x 0.3) = 8.16/0.075 =109
The cost factor against helmet laws is then more than 100 to 1. Put simply, helmet laws are not worthwhile because the health loss is far greater than the possible gains.’
In addition, the injury risk compared to cycling levels was found to have increased.
It concludes with, ‘Based on available evidence, helmet laws should be repealed because several reports raise serious doubts whether helmet wearing improves safety overall and the resulting harm to health, environment and social consequences are considerable’.
The New Zealand helmet law evaluation reported:
"This evaluation of NZ’s bicycle helmet law finds it has failed in aspects of promoting cycling, safety, health, accident compensation, environmental issues and civil liberties. It is estimated to cost about 53 lives per year in premature deaths and result in thousands of fines plus legal aspects of discrimination in accident compensation cases. Road safety and cyclist’s safety should be improved by coherent policies, which support health, the environment, and without the legal requirement to wear a helmet (ref 2).
For Canada concerns have been expressed about discouraging cycling and a possible higher accident rate resulting from helmet use (ref 3, 4).
A recent report on the USA also indicates a discouraging effect from helmet legislation and the safety outcome is questionable (ref 5).
One question that emerges is why helmet use should increase the accident rate. One reason to investigate is when cyclists hit potholes. A rider travelling at about 12mph (20km/hr) or 5m/s and hitting a pothole, for example 300mm wide, may take about 0.05 seconds to cover the distance. A typical reaction time may be about 0.1- 0.2 seconds, so the rider would not have time to react to any forces from the pothole impact. Reportedly up to 10g forces to helmets can occur from hitting deep potholes (ref 6). Helmets may add 5% to 10% extra to the bare head mass. The forces on the head would likely be higher for a helmet wearer and in random directions and the out of balance forces from the impact on the rider and bicycle may vary in direction. As a consequence wearing a helmet increases the risk of falling by incurring extra forces that the rider may not have time to react to. Perhaps some research could investigate this issue.
References
1 Clarke CF, Evaluation of Australia's bicycle helmet laws, The Sports Science Summit, London UK 2015 http://www.cycle-helmets.com/au-assessment-2015.pdf
2 Clarke, CF, Evaluation of New Zealand's bicycle law, NZMJ 10 February 2012, Vol 125 No 1349 http://www.cycle-helmets.com/nz-clarke-2012.pdf accessed 11.1.2014
3 Clarke CF, Response to; Helmet legislation and admissions to hospital for cycling related head injuries in Canadian provinces and territories: interrupted time series analysis, http://www.bmj.com/content/346/bmj.f2674/rr/646082
4 Clarke CF, Evaluating bicycle helmet use and legislation in Canada, http://www.cycle-helmets.com/canada-helmet-assessment.doc
5 Gillham C, Rissel C, Children’s cycling participation, injuries, fatalities and helmet legislation in the United States, World Transport Policy and Practice Volume 21.1 January 2015, http://www.eco-logica.co.uk/pdf/wtpp21.1.pdf
Competing interests: No competing interests
Goldacre and Spiegelhalter state that the Dennis study “has somewhat superior methodology – controlling for background tends and modelling head injuries as a proportion of all cycling injuries”. However, several population level helmet law studies have controlled for background trends and included both head and non-head injuries, and shown that the effect of the legislation on hospital admissions for cycling head injuries to be far from minimal:
- Carr/MUARC (1995), http://www.monash.edu.au/miri/research/reports/muarc076.html (Victoria, Australia)
- Hendrie (1999), http://www.ors.wa.gov.au/Documents/Cyclists/ors-cyclists-report-helmets-... (Western Australia)
- Povey (1999), http://www.ncbi.nlm.nih.gov/pubmed/10487351 (New Zealand)
- Scuffham (2000), http://www.ncbi.nlm.nih.gov/pubmed/10487351 (New Zealand)
- Karkhaneh (2006), https://era.library.ualberta.ca/public/view/item/uuid:432ec921-cf50-4b91... (Alberta, Canada)
- Walter (2011), http://www.ncbi.nlm.nih.gov/pubmed/21819836 (New South Wales, Australia)
The head injury results in all these population-level longitudinal studies, and the AIS3/4 head/brain injury results in the Carr study, are consistent with the (hospital control) results of the Thompson Cochrane Review, and the Attewell and Elvik meta-analyses, of case-control studies.
Dennis et al. cite the Scuffham and Walter studies as being "limited by sample size or methodological quality". However both the Scuffham and Walter analyses took baseline trends into account, and had (more than) adequate sample sizes.
The Walter study had 18 (monthly) time points before the New South Wales helmet law, and 18 after the law. The Dennis study had a total of 15 (yearly) time points.
In the case of Ontario (30% of the 1994 injuries), where the helmet law was Oct 95, there was only a single true pre-law time point. Each year of data is April to March, so the ‘1995’ data, which was treated as pre-law, actually contained both pre- and post-law data.
For British Columbia (19% of the 1994 injuries), the helmet law was Sep 96, Dennis et al. treated 1996 as the year the intervention occurred. However, they note that the Canadian cycling season runs to September, so 1996 would have been treated as post-law, when in fact much of the data would have been pre-law.
Collinearity between 'time' and 'time since intervention' may also have contributed to the “minimal effect” finding.
Macpherson claimed that the Povey and Scuffham analyses, and a preliminary (1992) MUARC study by Cameron, "failed to include a concurrent control group in the analysis"; however all 3 analyses used cyclist non-head injuries as concurrent control groups. (Povey's and Scuffham's analyses also included non-cyclist injuries.) Dennis also cites the preliminary 1992 Cameron/MUARC study; both Macpherson and Dennis have apparently overlooked the (1995) Carr/MUARC study (4 years of post-law data), which superceded the (1992) Cameron study (1 year of post-law data).
This (2013) paper debunks the Fyhri and Walker risk compensation, and Robinson safety in numbers, claims: http://acrs.org.au/wp-content/uploads/26_Olivier_PR.pdf also see http://injurystats.wordpress.com/author/jakeolivier/).
Competing interests: No competing interests
I have never needed my helmet* and hope to end my cycling days without ever having needed it. However, I wear it because, if I ever do need a helmet, I will really need it. (I always wear a leather jacket when cycling for similar reasons: I am fond of my elbows and would like to keep them.)
It may be, as some have argued, that not wearing a helmet actually confers some degree of increased safety but I would argue that a slightly reduced risk of head injury does not justify a 100% reduction in cranial protection.
The above notwithstanding, I would argue against any attempt to legislate for compulsory helmet-wearing (except possibly among children). The lack of a helmet is a convenient and obvious signifier to all other road users that a cyclist is more likely to act in a careless or stupid manner.
On the other hand, a helmet indicates a cyclist who is prepared to take personal responsibility for their own safety, and who is therefore likely to cycle carefully and take a responsible approach to road safety in general.
When overtaking another cyclist, I always give a significantly wider berth to those without helmets. Legislation would remove this handy distinction.
*Except when using the lower rank of two-level cycle storage.
Competing interests: Founder and former co-ordinator of Spokes: The NHS Cycling Network
The conclusion of "it's complicated" for cycle helmet efficacy at societal or individual level sounds like something of a cop-out, but it is in fact a significant step forward in a culture where the public (and in particular the school children we hope to be the next generation of regular cyclists) are still widely exposed to a simple, simplistic message that wearing a helmet to cycle is a "no brainer", several years after I noted in the BMJ (http://www.bmj.com/content/332/7545/852.3) that continual pressure to wear helmets is unlikely to allow intelligent risk assessment of or foster confidence in the safety of cycling.
Some progress has been made in that time, with Parliamentary Under Secretary of State for Transport Norman Baker stating on live TV that he did not ride with a helmet as he considered cycling safe enough not to warrant one, British Cycling having dropped their insistence that helmets are "essential" for transport and leisure users and the Association of Bikeability Schemes seeing fit to show unhelmeted children at the head of their website amongst other positive incremental points. However, there still remains a long way to go before the risks of cycling are assessed by the general public in a similar way to other everyday activities that are comparably safe.
That credible public scientific figures have pointed out in a BMJ editorial that helmet wearing on a bike is not just a simple message to be parroted unthinkingly will hopefully help realistic assessment of cycling risk move towards something like normality in the UK.
Competing interests: No competing interests
Like many cyclists I have been involved in an accident where I felt that I had been saved by my helmet which split in two when I was unfortunate enough to hit a car at speed. It initially stands to reason that wearing a helmet must therefore be a good thing.
It is however very interesting to look closely at the design spec for cycle helmets. The expanded polystyrene foam produces a limited “crumple zone” that has to be light enough to be tolerated during aerobic activity. The level of protection offered is “less than that given by helmets for motorcycle riders and is intended to give protection in the kind of accident in which the rider falls onto the road without other vehicles being involved.” (1)
It has been estimated that the forces generated once another vehicle is involved would exceed the design specification of a grand prix racing car helmet (2), which no cyclist would want to wear.
I still wear a helmet while commuting through London, partly because the lights attached to it make me more visible and partly out of force of habit from a childhood spent mountain biking in the Lake District. But rather than place emphasis on the wearing of a material which objectively provides very limited protection it would make more sense to focus on measures which avoid cyclists coming into contact with cars in the first place.
(1) BSI Standard 6863:1987
(2) “Heads Up”, B Walker, Cycle, June/July 2005, p42-45
Competing interests: No competing interests
So it's all very complicated then!
As a sociologist I am sure you will understand that I am attracted to complicated explanations that end inconclusively and dispense with the idea that more data will solve the puzzle. As a cyclist (rather than a public health official or legislator) I am left with the rather more simple question of whether I should continue to wear a helmet.
The answer seems to be yes as long as I don’t let it make me feel invulnerable. Apart from the fact that the helmet might attract a few drivers to whizz past a bit closer, they seem to offer some protection and, in my case, wearing one doesn’t put me off cycling. Thanks, Ben and David!
Competing interests: No competing interests
As alluded to by Goldacre and Spiegelhalter<1>, between questions about (a) whether helmets prevent head injuries and (b) whether helmet legislation would do more good than harm is a question with immediate practical implications in all jurisdictions: Should bicycle helmet use be promoted?
Should we encourage cyclists to wear helmets through public awareness campaigns, financial incentives such as tax breaks on the purchase of helmets, or the distribution of free helmets to some cyclists (e.g. children)? Mandatory helmet legislation is controversial largely because of concern that it would decrease cycling rates. It is more difficult to see how helmet promotion would decrease cycling rates. It also unlikely that cyclists would wear a helmet but improperly merely to comply with a societal norm but, as Goldacre and Spiegelhalter point out, they might do so to comply with a law.
Ideally helmet promotion would be one facet of a coordinated strategy to encourage (safe) cycling by improving roadway infrastructure, enacting and enforcing laws that protect vulnerable road users from motor vehicles, and promoting other safe cycling behaviors.<2> If cycling was safer and more cyclists wore helmets, questions about helmet legislation enactment and enforcement would fade away.
References
<1> Goldacre B & Spiegelhalter D. Bicycle helmets and the law. BMJ 2013;346:f3817
<2> Office of the Chief Coroner for Ontario. Cycling death review, June 2012. Available: www .mcscs .jus .gov .on .ca /stellent /groups /public /@mcscs /@www /@com /documents /webasset /ec159773 .pdf (accessed 2012 Oct. 2).
Competing interests: No competing interests
Some studies suggest that bike helmets are counter productive. By making people think that cycling is dangerous, they discourage cycling, whereas the health benefits of cycling far outway the dangers. And helmets might protect someone should they fall on the crown of their head at slow speeds, but won't offer any protection against other, far more common, damage. And certainly not in a collision with a car or lorry.
http://www.nytimes.com/2012/09/30/sunday-review/to-encourage-biking-citi...
Competing interests: No competing interests
benefits of compulsory helmets for motorists could be greater than benefits of compulsory helmets for cyclists
More motorists experience fatal injuries than cyclists. UK Government statistics for road casualties in 2013 by road user type, show that car occupants were the largest casualty type across all severities. Of the 1,713 people killed in reported accidents in 2013, 46 per cent were car occupants. Pedestrians were the second largest casualty type followed by motorcyclists, accounting for 23 per cent and 19 per cent respectively. Cyclists accounted for 6%. Ie car users comprise more than seven times as many road casualties as cyclists. (https://www.gov.uk/government/uploads/system/uploads/attachment_data/fil...)
Australian research indicates that improved head protection for car users is an important and feasible target for intervention:
"Car crashes remain a significant source of head injury in the community. Car occupants have an annual hospital admission rate of around 90 per 100,000 population. Of drivers who are admitted to hospital, the most serious injury is usually to the head (O'Conner and Trembath, 1994).
In a previous study, McLean et al. (1997) estimated the benefits that are likely to accrue to Australia from the use of padding of the upper interior of the passenger compartment. This study specifically examined the effects of the ammendment to the United States Federal Motor Vehicle Safety Standard 201 (FMVSS 201) in which passenger cars have to pass head impact tests with the upper interior. That report estimated the total annual reduction in harm to the Australian community to be around $123 million.
But more impressive were the estimates of introducing protective headwear for car occupants. The authors of the report estimated that the annual reduction in harm would be in the order of $380 million. The benefit of padding the head is that the head is protected from strikes with unpadded automotive components, exterior objects and in vehicles that predate any eventual introduction of padded interiors." These are Australian numbers. (http://www.copenhagenize.com/2009/10/australian-helmet-science-for-motor...)
Compulsory helmets for cyclists, by reducing cycling, risks reducing the public health benefits of cycling as part of an active lifestyle.
If compulsory helmets for car users discouraged car use this would have a positive effect on population health as car users moved to public transport, walking and cycling, reducing harmful emissions and increasing physical activity.
Legislation for compulsory helmets should be directed towards car occupants as this would have a greater impact on public health and health costs than legislation for cycle helmets.
Competing interests: No competing interests