Many suspected drink drivers on drugs

[Posted: Thu 14/12/2006 - www.irishhealth.com]

A new study has found that a significant number of Irish drivers who were suspected of drink driving but were then found to be below the legal blood alcohol level, later tested positive for a range of drugs.

The researchers from UCD's School of Public Health and Population Science based their findings on 2,000 blood and urine samples, which were taken from drivers who had been stopped by Gardai on suspicion of drink driving.

Half of the drivers were found to be above the maximum legal alcohol limit of 80mg/100ml for blood and 107mg/100ml for urine. The other half were below the legal limit.

However when analysed, the researchers found that among those who had been below the legal drink drive limit, one in three tested positive for a range of drugs. These included amphetamines, cocaine and the heroin substitute, methadone. The most commonly detected drug was cannabis.

Men were slightly more likely than women to test positive for drug use.

Based on the samples in the study, the researchers calculated that almost 16% - or one in six drivers - stopped and tested under suspicion of drink driving, would test positive for drugs. They believe that all drivers who are stopped on suspicion of drink driving should be tested for drug use as a matter of routine.

"Being under the legal limit for alcohol, being stopped in a city, being stopped between 6am and 4pm or between 4pm and 9pm and being under 35 years of age, were all independently associated with drug taking. Too little attention has been paid to the adverse effects of drugs on driving, but drugged driving can be as dangerous as drunken driving", they said.

Details of these findings are published in the medical journal, Injury Prevention.

Rich  Posted: 20/12/2006 17:04

Testing positive for drugs other than alcohol doesn't tell us reliably whether or not someone was driving under their influence. With alcohol we can know somebody's blood alcohol concentration at that moment & from that we can infer levels of consumption over the past 12 hours. Tests for other drugs are less sensitive. They can only tell us whether the drug is present or not, not concentrations in the blood, & can give positive results sometime after it was last used: light cannabis smokers up to a week, benzodiazpines up to 5 days, opiates similarly & even stimulants like speed or cocaine, 1 or 2 days. I think it's hard to argue that someone driving under the influence of even legal amounts of alcohol has their driving further impaired by a spliff they smoked a week ago. The interesting question for me is who funded this research? What we do know is: -driving ability is impaired above a BAC of 50mg% but the current limit in the Republic of Ireland is 80mg%; -the drinks industry is against any reduction in the drink-driving limit. Is giving publicity to research like this a way of diverting attention away from what really needs to be done: reducing the current limit & enforcing it rigorously with random breath testing?

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