Alcohol and drug detection rates in road traffic: An international comparison

Driving under the influence of alcohol or drugs is a significant contributing factor to road traffic crashes. Detection rates for alcohol and drugs among drivers in random road traffic have been studied in several countries; this article presents a comprehensive overview of findings in studies conducted from 2010 to 2024. We searched PubMed, Google Scholar, Google Search, and the International Council on Alcohol, Drugs and Traffic Safety Conference Papers database. We also examined reference lists and citation records. We identified 53 studies, of which 25 studies focused exclusively on alcohol. The studies were conducted across 24 countries. Alcohol was the most frequently detected substance, followed by tetrahydrocannabinol (THC). Detection rates exhibited variability across jurisdictions; alcohol was most commonly observed in studies conducted in North America and in some low- and middle-income countries, whereas THC and cocaine were most frequently detected in studies from North America, Italy, and Spain. Several countries have implemented effective measures that have led to a significant reduction in the incidence of drink-driving. However, despite the introduction of legal thresholds or zero-tolerance policies for drug-impaired driving, the detection of drugs among drivers has increased in certain regions.