Driving under the influence of drugs, alcohol and medicines

New EMCDDA report reveals risks of substance use behind the wheel

The use of illicit drugs and psychoactive medicines amongst drivers, particularly when combined with alcohol, is described today in a new report from the EU drugs agency (EMCDDA) (1). The ‘state of the art’ review presents the results of the largest research project ever carried out in the EU on Driving under the influence of drugs, alcohol and medicines (the ‘DRUID’ project), which ran between 2006 and 2011 (2).

Around 30 000 people die in traffic accidents in the EU every year, with alcohol still the number one substance endangering lives on Europe’s roads (around one quarter of road deaths). The European Commission funded the DRUID project in order to assess the scale of Europe’s drink- and drug-driving problem and contribute key evidence to road safety policy. It culminated in 50 project reports, running to several thousand pages. The new 50-page EMCDDA review summarises the findings of these reports.

For the first time using comparable data, the project drew a map of the drink- and drug-driving problem across  13 European countries (Figure 2). Over 50 000 car and van drivers were tested in random roadside surveys for traces of 25 substances, including illicit drugs, alcohol and medicines. Alcohol was detected in 3.5 % of drivers, illicit drugs in 1.9 % and medicines in 1.4 %. Mixtures of drugs or medicines were found in 0.39 % of those stopped and combinations of alcohol with drugs or medicines in 0.37 %. A series of project recommendations are made to counter driving impaired by substance use.

The roadside surveys revealed cannabis (THC) to be the most frequently detected illicit drug in drivers, followed by cocaine and amphetamines. Meanwhile, benzodiazepines were the most frequently found medicine, with medicinal opioids less common.
Across Europe, the prevalence of alcohol, cocaine, cannabis and combined substance use was found to be higher in southern and western regions. Medicinal opioids were detected more in northern Europe, while substance use was relatively low in most of the eastern region. Alcohol and drugs were found more often in male drivers, while medicines were identified mainly in middle-aged and older female drivers.

Commenting today Wolfgang Götz, EMCDDA Director, said: ‘The DRUID project has given policymakers the best available scientific evidence on levels of drug and alcohol use in drivers and the responses available today to improve road safety in Europe. The EMCDDA is proud to be associated with this project, which has set the standard for assessing drug driving in European countries in order to design more effective solutions in future’.

Also examined in the study were data from nine countries on drivers seriously injured or killed in traffic accidents. In sharp contrast to the results of the roadside tests, between a quarter and a half of drivers involved in crashes in these countries (28 % to 53 %) tested positive for one or more psychoactive substance (Figure 3).

Overall, 24.4 % of the injured driver population and 31.7 % of the killed driver population tested positive for alcohol, around 70 % of these being severely intoxicated (blood alcohol content ≥ 1.2 g/l). Among those testing positive for alcohol, the highest percentage of seriously injured drivers was found in Belgium and the highest percentage of drivers killed in accidents found in Portugal. Among those testing positive for cannabis, the highest percentage of seriously injured drivers was again found in Belgium and the highest percentage of drivers killed in accidents in Norway. Cocaine use appeared to be more common in southern Europe.

The project looked at how different substances can impair driving and calculated the risks of being seriously injured or killed while driving with psychoactive substances in the body (Table 2). The findings disprove the common belief that illicit stimulants enhance driving or counter alcohol and lack of sleep. Studies found that stimulants are often taken in very high doses which can have detrimental effects on self perception, critical judgment and risk-taking. These effects are greatly increased when stimulants are combined with alcohol.

Responding to drink- and drug-driving in Europe

Today’s report describes some of the positive responses to drink- and drug-driving developed in Europe. Effective prevention initiatives include training programmes and support tools to help doctors and pharmacists review their prescribing and dispensing practices and advise on the effects of medicines on driving performance. For the patients who take those medicines, pictograms on medicine packages, using DRUID’s four-level classification and labelling system, have been shown to be effective in communicating risk. Information campaigns targeting young people, however, are rarely evaluated and thus their effectiveness remains unclear.

Three options commonly used by policymakers to address drink- and drug-driving are: ‘impairment’ (proof that the substance has impaired driving ability); ‘legal limit’ (‘over the limit’ being an offence) and ‘zero tolerance’ (any amount found being an offence). At present, 11 countries in Europe use the ‘impairment’ approach, while eight use the ‘zero tolerance’ or ‘legal limit’ approach. Nine countries combine these two approaches into a two-tier system, the option recommended by the project. Enforcing these laws, however, remains a challenge due to accuracy concerns regarding drug-testing procedures. None of the roadside oral fluid testing devices achieved the target value of 80 % sensitivity, specificity and accuracy for all the individual substances tested.

The DRUID project illustrated the measurable increased risk to road safety posed by illicit drugs. Yet, a cost–benefit analysis carried out under the project warned public authorities to think carefully before switching resources from alcohol to drug detection. The scale of the threat posed by alcohol, combined with a continued lack of adequate drug detection devices at the roadside, means that road user safety might suffer from such a switch. As the report explains: ‘As the risk and share of injuries is higher for alcohol, targeting driving under the influence of alcohol should always be the first priority of law enforcers.’


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