A significant increase in the incidence of driving under the influence of drugs has been found in a new survey by the Medical Bureau of Road Safety.
Some 37 per cent of samples taken from drivers who were stopped by gardai last year on suspicion of drink driving, but found to be under the legal alcohol limit, tested positive for drugs.
This compares to just 14.6 per cent in a survey conducted between 1987 and 1991.
Cannabis was found to be the most common drug, showing up in 34 per cent of samples, minor tranquillisers or benzodiazepines in 25 per cent, amphetamines such as ecstasy in 16 per cent, opiates in 14 per cent, methadone in 7 per cent and cocaine in 4 per cent.
The occurrence of polydrug use was frequent with 45 per cent of positive samples containing two or more types of drugs, and 3 per cent containing five types of drug.
Prof Denis Cusack, of the bureau, which operates through University College Dublin's department of forensic medicine, said the findings highlighted the need for a major public awareness campaign on the dangers of drug-driving.
He said the bureau would be proposing such a public awareness campaign when it meets a Department of Environment and Local Government committee on road safety in the coming weeks.
The Garda Siochana does not have figures for drug-driving convictions but a Garda spokesman said they accounted for less than 5 per cent of convictions under the 1961 Road Traffic Act, which made driving under the influence of an intoxicant, including alcohol, a criminal offence.
Under the Act, limits for drug intake are not specified. Rather, it up to the medical professional in a particular case to decide whether a drug contributed to driver impairment.
A total of 338 samples were tested between June and December last year for the study.
While all samples taken were under the legal alcohol limit, alcohol was discovered in four out of five cases. The survey noted that driver impairment could be greatly enhanced by the interaction between drugs and alcohol, even at low levels.
