There is growing concern around the world about drug use and road safety. Drinking alcohol and driving is a well studied risk factor for road traffic crashes, injuries and deaths but drug-induced impairment of driving is causing increasing concern in many countries around the world
For many years there have been several gaps in our knowledge, particularly about the global extent of the problem, the relationship between drug concentrations and crash risk, appropriate threshold limits in blood, legislation and enforcement of effective measures to prevent drug-driving. However, these knowledge gaps are progressively being filled by a growing body of evidence on drug use and road safety, including effective ways to reduce drug-induced road traffic crashes and injuries.
Psychoactive drugs affect the functioning of the brain and may lead to impaired driving (e.g. by delaying reaction time and information processing, reducing perceptual-motor coordination and motor performance, as well as attention, road tracking and vehicle control).
Prevention and early interventions
Measures that need to be in place and implemented in a comprehensive manner cover five essential areas: legislation, testing, enforcement, awareness-raising, and counselling and treatment.
Establishing drug-driving laws and regulations
The type of legal framework varies according to the social, legal and economic characteristics of a particular jurisdiction, as well as the historical context of the development of laws designed to improve road user safety.
- Zero tolerance laws make it unlawful to drive with any amount of specified drugs in the body.
- Impairment laws make it unlawful to drive when the ability to drive has become impaired following drug use, often described as being “under the influence” or in similar terms.
- Per se laws make it unlawful to drive with amounts of specified drugs that exceed the maximum set concentration. The specific link between drug concentration, impairment and the risk of a crash still needs more research. To date, a few countries, including the United Kingdom, have adopted per se laws.
A total of 159 countries around the world have national legislation prohibiting drug- driving but most of these laws do not define what is considered to be a “drug”, nor do they specify a threshold. It will be difficult to enforce drug-driving laws in countries that have neither defined what is considered to be a “drug” nor specified a threshold.
Using drugs with or after drinking alcohol is never a good idea. People who combine alcohol and drugs are twice as likely to be involved in a crash as those drinking alcohol alone. Drivers with a BAC of more than 0.08 g/100 ml who combine drugs with alcohol are a hundred times more likely to be injured in a road crash.