Dept. of Unexpected Side Effects

Seatbelts Make Us Safer . . . Right?

This text was scraped from the Electronic Letters to the BMJ (British Medical Journal); it was in response to the challenging Three Lessons for a Better Cycling Future by M J Wardlaw. Wardlaw's article calls for putting responsibility for road danger where it belongs: with drivers. He says that cyclists are being blamed for "risk taking" which is in fact due to bad drivers and excessive use of the automobile. Wardlaw challenges official responses such as mandatory helmeting of cyclists, etc. as ineffectual and producing more harm than good by discouraging and stigmatizing cycling.

Shane Foran writes from Galway with some very unsettling research about automotive seatbelt laws. These are usually regarded as a victory for consumers and for public safety. Foran says otherwise:

In his piece "Three lessons for a better cycling future" (23 December) Malcom Wardlaw raises the issue that the UK seatbelt legislation may have resulted in a more dangerous road environment for cyclists(1). The history of seatbelt legislation is of drastic effects for those outside cars such as pedestrians, cyclists and motorcyclists. The imposition of the UK seatbelt law was accompanied by increases in deaths to pedestrians of 135 per year and of deaths to cyclists of 40 per year(2). Similar effects for non-car occupants are reported from Australia(3), New Zealand(4) and Canada(5). In 1981 the UK Department of Transport commissioned a study on the effects of seatbelt legislation in Sweden, West Germany, Denmark, Spain,Belgium, Finland, the Netherlands and Norway. The study, "the Isles report"(6,7) which was subsequently suppressed, used the UK and Italy as controls for non-seatbelt countries.

When the wider effects were examined the author was alarmed to find that the predominant effect was of increased numbers of injuries to non-car users. In fact the author tentatively predicted that in the UK deaths to other road users would climb by 150 per year in the event of compulsory seatbelt wearing legislation. In terms of injuries the prediction was for a 11% increase in pedestrian injuries with injuries to other road users climbing by 12 to 13% (numerically 7,000 and 36,000 respectively). A recent analysis of the rise in injuries seen following the UK law suggests that drivers who started wearing seatbelts were 11-13% more likely to injure pedestrians and 7-8% more likely to injure cyclists(8).

Vehicle occupants

In countries such as Ireland(9), Sweden(10) and New Zealand(4) compulsory seatbelt wearing legislation was accompanied by increases in deaths among car occupants. The "Isles report" on the experiences of eight European countries predicted that in the UK a seatbelt law would be followed by a 2.3% increase in fatalities among car occupants.

Mr. Wardlaw repeats the common claim that the UK's seatbelt legislation actually resulted in a 25% reduction in deaths among drivers and front seat passengers. However, there were two major road safety interventions in the UK in 1983. A major drink driving campaign using evidential breath testing also accompanied the compulsory seatbelt law. In 1983, 23% of the fall in road deaths occurred between 10pm and 4am, 3% of the fall occurred at other hours of the day (11). Was this predominantly an effect of seatbelts or of breathalysers? Or was there some other underlying trend?

What about car passengers?

In the UK the introduction of compulsory seatbelts for front seat occupants was accompanied by a 75 per year increase in deaths among rear seat occupants (2). This suggests that seatbelt wearing by drivers had a negative effect on survival expectancies for rear seat passengers. This also seems to provide an argument for making these passengers wear seatbelts as well. However this issue is not clear-cut. In crashes, small children who wear adult seatbelts suffer characteristic "seat-belt syndrome" injuries including severed intestines, ruptured diaphragms and spinal damage. Recent research suggests that children in inappropriate restraints are also at significantly increased risk of head injury (12).

Indeed, one of the authors of that study has publicly stated that "The early graduation of kids into adult lap and shoulder belts is a leading cause of child-occupant injuries and deaths."(13) In 1989 the UK extended compulsory seatbelt wearing to child passengers under the age of 14.

Among these children, this measure was accompanied by a 10% increase in fatalities and a 12% increase in injuries(11). I cannot claim cause and effect but the suggestion would be no more or less tenuous than some of the claims that have been made for cycling helmets.

Why does seat belt legislation have this effect?

For adults the protective effect of seatbelts is generally accepted so explanations have focused on driver behaviour. There are two related theories, the Risk Homeostasis and Risk Compensation hypotheses (14). These both argue that drivers adjust their driving behaviour in response to an increased sense of personal safety.

A slightly different emphasis was recently offered via the British Psychological Society(15). This proposes that during near misses the actual physical restraint experienced by seatbelt wearers leads to a reduced sense of threat to life. A reduced sense of threat may then lead to the adoption of a more dangerous driving style.

Other researchers have attempted to explain the failure of seatbelt laws by appealing to the Selective Recruitment hypothesis. This argues that seatbelt laws haven't had the expected results for vehicle occupants because those drivers who take the most risks are also the least likely to use seatbelts(16). Unfortunately the Selective Recruitment hypothesis does not explain why road deaths should remain unchanged or even go up following seatbelt laws.

The evidence in favour of seatbelt legislation.

The advocates of seatbelt legislation tend to rely on two types of study, experiments using crash test dummies and hospital based studies. Experiments using crash test dummies do not allow for any effect of seatbelt wearing on driving behaviour. In hospital based studies one or more hospitals may report a reduction in fatalities and injuries to car occupants. However there is an inconsistency between individual hospital based studies showing one effect and the larger, and for deaths more reliable, population based studies that show no such effect or even the opposite effect. This suggests that for some reason other hospitals are choosing not to publish their results(17).

It is now accepted that there can indeed be a problem of bias in how results from medical and other studies actually get offered for publication(18). This "missing data problem"(19) has prompted journals including the British Medical Journal and the Lancet to set up a special register for documenting unpublished studies. If this bias has been found with studies of therapeutic interventions then it is no less likely to occur with studies of "road safety" interventions. The advocates of seatbelt laws must also choose to disregard the effects of such measures for people outside cars.

A historical curiosity or pressing problem?

In the UK the effect of seatbelt legislation might be seen as a historical curiosity. In my own country, Ireland, the issue is extremely current as the authorities are currently trying to raise seatbelt-wearing rates by Irish motorists from app. 55% to 85% or higher by using new "on the spot fines". Seatbelt wearing is being pushed at a time when there is an apparent policy of non-enforcement of the speed regulations in Irish towns. In residential areas 68% of drivers break the existing, excessively high, speed limits. On main roads in 30mph limit zones the average free speed of cars is 45 mph(20). In impacts occurring at these speeds a pedestrian has a less than 1 in 10 chance of survival. Ireland already has the highest child pedestrian death rate and third highest pedestrian death rate in the EU.

In my home town of Galway 28% of accidents involve pedestrians but these account for 43% of the fatalities in the city. In Galway City it has been found that in 71% of injury accidents involving motor vehicles the driver is unscathed(21), this amply demonstrates where car centred "road safety" policies have placed, and continue to place, the burden of death and injuries. Ireland has among the highest levels of heart disease and obesity in the EU and is facing a public health crisis as government policy forces more and more cyclists and pedestrians off the roads. About 13,000 Irish citizens die of heart disease and related conditions annually. Things get even worse when western, car centred, "road safety" practices get exported to the third world. In developing countries death rates per vehicle are up to a hundred times higher than in rich countries(22).

A time for leadership.

Mr. Wardlaw takes a light-hearted dig at helmet wearing initiatives. Others have noted that cyclists tend to react with anger and vituperation to calls for us to use cycle helmets(23). We would point out that the environment of threat we experience on the public roads was created with the complicity of many, including medical professionals, who would now have us wear helmets. It is a reasonable human reaction to view calls for helmet wearing as the ultimate in hypocrisy and victim blaming.

It is time for a change in attitudes to road safety and traffic management. The environmental and public health imperatives such a change are well established. There is a wider issue however. There is something fundamentally wrong with a society, which places a premium on one person's life over another's, purely on the basis of their choice in transportation. It is time for the wider medical profession to offer leadership in changing this situation.


1. Wardlaw MJ, Three lessons for a better cycling future, BMJ 2000;321:1582-1585

2. West-Oram F, Casualty Reductions whose Problem?, Traffic Engineering and Control, Sept. 1990

3. Coneybeare JAC, Evaluation of Automobile Safety Regulations: The case of Compulsory Seat Belt Legislation in Australia, Policy Sciences 12:27-39, 1980

4. Hurst P, Compulsory Seat Belt Use: Further Inferences, Accident Analysis and Prevention, Vol 11: 27-33, 1979

5. Wilde GS, Risk Homeostasis and Traffic Accidents Propositions , Deductions and Discussion of Dissension in Recent Reactions, Ergonomics, 1988 Vol, 31, 4:439

6. Davis R, Death on the Streets, Cars and the Mythology of Road Safety, Leading Edge Press, North Yorkshire UK, 1992

7. Hamer M, Report questions whether seat belts save lives, New Scientist, 7/2/1985 p7

8. Dulisse B, Methodological Issues in Testing the Hypothesis of Risk Compensation, Accident Analysis and Prevention Vol. 25 (5): 285-292, 1997

9. Hearne R, RS 255 The initial impact of seat belt legislation in Ireland, An Foras Forbatha, Dublin, 1981

10. Adams J, The efficacy of seatbelt legislation: A comparative study of road accident fatality statistics from 18 countries, Dept of Geography University College, London 1981

11. Adams J, Risk, UCL Press Ltd. University College, London 1995

12. Winston FK, Durbin DR, Kallan MJ, Moll EK, The Danger of Premature Graduation to Seat Belts for Young Children, Pediatrics, Vol. 105, No. 6, June 2000, pp. 1179-1183

13. Karp H, Kids at Risk: When Seatbelts are NOT Enough, Reader's Digest (US Edition), November 1999

14. Wilde GS, Target Risk, PDE Publications, 1994

15. Press Release of the Annual Conference of the British Psychological Society, The Puzzle of Seat Belts Explained, April 1999

16. Dee TS, Reconsidering the effects of Seatbelt Laws and Their Enforcement Status, Accident Analysis and Prevention, Vol 30(1): 1-10, 1998

17. Adams J, Risk and Freedom, The Record of Road Safety. Transport Publishing Projects, Cardiff, 1985

18. Egger M, Smith GD, Schneider M, Minder C, Bias in meta-analysis detected by a simple, graphical test, BMJ 1997;315:629-634

19. Mathews R, Hidden Truths, New Scientist 23/5/99 pp 28-33

20. National Roads Authority, RS 453 Free Speeds on Urban Roads, Dublin, 2000

21. Brennan MJ, Connolly D, The Pattern of Traffic Accidents in Galway City Over a Decade, Local Authority News , Vol 14 No. 4 pp 39-43, 1997

22. Pearce F, Collision Course, New Scientist 1/8/98 p44

23. Rivara P, Thompson DC, Thompson RS, Reply to critics of bicycle helmet editorial, 8 December 2000, Electronic responses to: Bicycle helmets: it's time to use them (

Galway Cycling Campaign -Feachtas Rothaiochta na Gaillimhe c/o Galway One World Centre, William St. West, Galway.

Shane Foran M.Sc., Cycle Campaigner, (Galway, Ireland) Previously worked in research and development of medical diagnostics, currently trying to engineer a switch to IT (Analyst/programmer). I also have the title of safety officer of the Galway Cycle Campiagn.
De Clarke