Monday, January 16, 2012

Opinion - Make drug-driving illegal, but prevention is better

Setting limits for drug-driving may prove tricky. A total ban, plus anti-drug campaigns for children, looks like the best solution

One of road safety's great success stories has been legislation coupled with appropriate enforcement. There is strong evidence that speed limits and a legal limit on blood alcohol content while driving have saved lives. So the UK government's decision to consider introducing a new offence of driving with an illegal drug in your body is welcome.
The government has established a panel of experts to examine the technical aspects of such legislation. Its terms of reference are still under development, but it will consider how such an offence could be defined and whether it is possible to set limits for illegal drugs like those for alcohol. That would mean identifying, for an average adult, levels for the impairing effects of specific drugs, including cocaine, MDMA, cannabis and opiates, that are broadly equivalent to the current blood alcohol limit, which in the UK is 80 milligrams of alcohol per 100 millilitres of blood.
This work is needed because the UK has no objective test for drug-driving – unlike drink-driving – no legal definition of impairment under UK road law, and no offence of driving in breach of limits of specific drugs. Motorists can be charged with being unfit to drive through drugs, but proof of impairment is needed and is hard to obtain, so few cases go to court. Technology is catching up, though. Roadside drug-screening devices exist and are used in other countries, although none is approved for use in the UK.
Why is action needed? There is mounting evidence of a drug-driving problem. For example, a report published in 2001 by the UK's Transport Research Laboratory studied 533 drivers, predominantly from London, who were fatally injured as a result of being involved in an accident. It found that just under 18 per cent of them tested positive for an illegal drug and just over 5 per cent had taken more than one.

Cocktail of trouble

The panel will face difficult decisions in applying the scientific process to determining actual limits, though. In the most closely analogous problem – drink-driving – the evidence for setting appropriate limits initially came from a 1964 study involving more than 17,000 drivers in Grand Rapids, Michigan. In this study, the blood alcohol level of drivers who had been involved in a crash reported to the police was compared with the blood alcohol level of drivers who had not. This allowed the researchers to estimate the odds of being involved in an accident at several levels of blood alcohol, and this information was used to set a legal limit.
The complexity of the drug-driving issue compared with drink-driving raises more problems and costs. For instance, more than one illegal substance can cause impairment: the Transport Research Laboratory study found traces of cannabis, amphetamines, cocaine, methadone and other opiates. If limits were set, they may not capture the complex interactions between drugs and the result on driving: a driver may be severely impaired but under the limit for each individual drug. Setting a legal limit for use of a substance that is illegal may also seem counter-intuitive.
There is a reasonably simple way to confront these complexities. A new offence of driving with any level of an illegal drug in the body might be the best way of emulating the success of drink-driving laws. It would make it much easier to catch and convict drug drivers – the ultimate deterrent.

Tough on causes

However, we also have to consider other ways to address behaviours that are the result of wider social structures and culture. Injuries on the road, like health, are influenced by many different social factors. Although people from a range of backgrounds use illegal drugs, deprivation, unemployment and social exclusion all foster environments in which young people are more likely to take them.
We do not have to wait until the age when people are most likely to misuse drugs and then drive before we tackle these matters. Studies based around the idea of early intervention and providing preschool support have found that this approach can reduce the use of drugs in later life. This could be a valuable and cost-effective way of reducing drug driving, especially given the much wider positive effects on health and well-being that early intervention can have.
Along with setting stronger laws about drug driving, interventions along these lines may have a valuable contribution in any strategy to save lives and prevent injuries on the road.

Duncan Vernon is road safety manager (England) at the Royal Society for the Prevention of Accidents

http://www.newscientist.com/

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