People... probably have no idea about the effects of drugs on their driving ability

Dr Vivienne Nathanson

It is calling for the government to co-ordinate scientific research to establish effective drug testing devices as soon as possible.

Between the 1985 and 1999 the number of people involved in fatal road accidents who tested positive for cannabis increased four-fold (3% to 12%).

Complex problem

The BMA fears that this number will rise given the increasing use of drugs.

Nearly half of 16-24 years old in England and Wales are reported as having tried cannabis and 39% claim to have taken hallucinogens.

However, the BMA warns that developing an effective device to assess the effects of drugs on driving ability is extremely complex.

Cannabis is the most widely used illegal drug

Levels of drugs in the body, degrees of impairment and how long a drug remains in the body all need to be evaluated.

Alcohol often exaggerates the effects of drugs so any testing device would also need to measure the potential effect of a drug when consumed with alcohol.

Cannabis effect

Cannabis is the most frequently detected illicit drug in accident fatalities and is known to impair co-ordination, visual perception, tracking and vigilance.

Yet findings relating the effects of cannabinoids on driving skills and road safety are not conclusive.

Drug drive death

Jane Boyd received an 18-month suspended prison sentence last June after the death of her daughter Kelly in a car crash in October 1999. Boyd, 39, was high on heroin and lost control of her Ford Escort which veered into a central reservation near Southampton. The car ran into the path of the lorry on the other side of the dual carriageway and collided side on.

The fact that cannabis can be found in blood as long as 28 days or even longer after last use demonstrates how difficult it would be to predict whether or not a driver's ability had been adversely affected by the drug.

Dr Vivienne Nathanson, BMA head of science and ethics, said: "Whatever action the government takes on drug driving it is essential that it is accompanied by a public awareness campaign.

"People generally accept that you shouldn't drink and drive but probably have no idea about the effects of drugs on their driving ability."

Dr Nathanson said legal drugs could also be a problem for drivers.

She said: "Millions of people regularly take drugs like anti-depressants, painkillers, anti-histamines and cough mixtures, all of which can have a sedative effect, and yet most of these people probably think it's totally safe for them to drive."

Driving while unfit under the influence of drugs is an offence and carries the same penalties as driving under the influence of alcohol.

However, the law does not state any legal limit for drugs as it does for alcohol.

Response

A spokesman for the Institute of Advanced Motorists said: "We would like to see clear health warnings on over-the-counter medicines."

A Department of Transport spokeswoman said the government was working to educate policemen on drug recognition techniques which would give them "greater confidence to arrest a suspect".

She said: "If a person is suspected of taking drugs and driving it is very difficult to prove it.

"Education and legislation would put police officers in a better position to make that judgment.

"We are also working on a new publicity campaign to target people who might take drugs and drive."