Attachment A - Efficacy of Helmet Wearing For Cyclists

Sound evidence that helmets can provide effective protection against head injury, brain injury in particular, has always been sparse, but such evidence and the confirmed absence of undesirable side effects are the first requirement of making helmet wearing a public safety measure, especially when compulsory use is contemplated. Yet a House of Representatives committee recommended in 1978 "that cyclists be advised of the safety benefits of helmets and the possibility of compulsory wearing be kept under review"[3] without adducing any evidence of the efficacy of helmets. They simply assumed it, and so did their successor committee in 1985: "It is, of course, this Committee's belief that all cyclists should wear a helmet to increase cycling safety".[4]

The only evidence of efficacy that the 1985 committee adduced to support their belief was from a study by Dorsch et al of the Road Accident Research Unit of the National Health and Medical Research Council (NHMRC).[18] Their data were obtained from returns to questionnaires and related to crashes up to 5 years earlier. The persons surveyed were mainly members of bicycle racing clubs not representative of the general population of cyclists. Reported injuries were statistically correlated with the wearing of helmets. Dorsch et al "estimated that the risk of death from head injury was considerably reduced for helmeted relative to unhelmeted bicyclists, depending on helmet type". The estimation of efficacy was based on an unpublished method however, and, like several studies since, was not linked to a coherent theory of the mechanism of head injury.

The current theory of the mechanics of head injury shows that rotational forces, not direct blows to the head which are simulated in testing helmets for cyclists,[32] are the main cause of injury to the brain[21][22]. The impact of a human head and body with a pavement can generate much greater rotational forces than say the impact of a bullet[21]. Contrary to the argument of one minister, the wearing of helmets by soldiers and construction workers provides no valid reason for cyclists to wear them[23]. The NHMRC took account of the theory of head injury in a 1994 study of football injuries[24]. After noting studies of helmets for cycling, it stated: "Whilst helmets may possibly reduce the incidence of scalp lacerations and other soft tissue injury, there is the risk that helmets may actually increase both the cerebral and non-cerebral injury rates. ... The addition of a helmet will increase both the size and mass of the head. This means that blows that would have been glancing become more solid and thus transmit increased rotational forces to the brain ... increase in diffuse brain injury".

Dorsch et al acknowledged shortcomings of their study including reporting bias as a source of systematic error and noted that further research was needed to confirm and refine their findings. It has not been done. Describing the Dorsch survey as based on a small sample of users, the Victorian Government stated that "the incidence of bicycle helmet use has not yet reached a sufficiently high level anywhere in the world for a scientific examination of helmet effectiveness in injury reduction to be undertaken".[19] Dorsch et al therefore did not prove the efficacy of helmet wearing and the first requirement for the compulsory helmets policy was not met. Despite this, the Federal Office of Road Safety told the 1985 committee: "it is appropriate to re-affirm unequivocally that the wearing of safety helmets by bicyclists is the principal means of reducing casualties in crashes. ... any doubts about the safety of helmets need to be quickly resolved. It is most important that there is no erosion of public confidence in the use of safety helmets."[19] .But FORS, the proper authority to advise the Government on the efficacy of helmet wearing, did no evaluation of it, nor did it seek advice from the NHMRC or other health authority.[2]

The 1985 committee thought the standard for helmets should allow for them to be better ventilated and lighter, especially for children, and suggested soft-shell helmets as being more acceptable to users.[4] Dorsch et al had, however, not studied the efficacy of soft-shell helmets, only the old-style hairnet helmets and hard shell helmets. On the committee's recommendation, FORS sponsored research on the standard. The authors of the research endorsed lighter helmets for children, having shown that the added mass of a helmet has the effect of increasing the rotational acceleration which a glancing blow may impart to the head[31]. Referring to its lethal effect, they said the shells of helmets should be very stiff with a low impact sliding reaction. FORS said: "This research was made available to Standards Australia and assisted one of its committees to recommend changes to the bicycle helmet standard. The amended standard allowed the introduction of `soft top' helmets, improving the comfort of helmets helping to overcome an obstacle in introducing mandatory helmet wearing".[30] To the extent that this statement implied some research backing for soft top helmets, it was a misrepresentation. The amendment to the standard compromised safety. Tests of impacts of helmets on asphalt at 34km/h have since shown that, unlike hard-shell helmets which slide, soft helmets grab the surface, rotating the head and producing angular accelerations of four to six times the tolerable maximum.[33] Government was negligent.

References

(numbers not in sequence because this is an extract from a longer paper)

2. Federal Department of Transport, response to FOI request, 21 September 1995.

3. House of Representatives Standing Committee on Road Safety, Report on motorcycle and bicycle safety inquiry, AGPS, 1978.

4. House of Representatives Standing Committee on Transport Safety, Final report on motorcycle and bicycle helmet safety inquiry, AGPS, 1985.

18. Dorsch, M.M., Wodward, A.J. and Somers, R.L., Do bicycle helmets reduce severity of head injury in real crashes?, Acc. Anal. & Prev. 19, 3, pp. 183-190, 1987.

19. Evidence to the House of Representatives Standing Committee on Transport Safety inquiry on motorcycle and bicycle helmet safety, 1985.

20. Dorsch, Margaret, submission to House of Representatives Standing Committee on Road(sic) Safety, 16 October 1984.

21. Holbourn, A.H.S., Mechanics of head injuries, The Lancet, 2, 338- 441, 1943.

22. Ommaya, A.K. and Gennarelli, T.A., Cerebral concussion and traumatic unconsciousness: correlations of experimental and clinical observations on blunt head injuries, Brain, 97, 633-654, 1974.

23. ACT Minister for Urban Services, Hansard, 19.5.92, p. 584.

24. National Health and Medical Research Council, Football injuries of the head and neck, AGPS, 1994.

30. Australian Transport Advisory Council, 79th meeting, minutes and verbatim, 21.12.89 (obtained under FOI).

31. Corner, J.P., Whitney, C.W., O'Rourke, N. and Morgan, D.E., Motorcycle and bicycle protective helmets: requirements resulting from a post crash study and experimental research, Federal Office of Road Safety report no.CR 55, Canberra 1987.

32. Standards Association of Australia, Australian Standard 2063.2, 1990.

33. Andersson, T., Larsson, P. and Sandberg, U., Chin strap forces in bicycle helmets, Swedish National Testing and Research Institute, Materials & Mechanics, SP report 1993:42.