Cannabis and amphetamines the drugs of choice for intoxicated drivers

Cannabis and amphetamine are the most frequently detected drugs in traffic stops by the police, according to research by the Netherlands Forensic Institute (NFI). An NFI chemist and toxicologist examined over 64,000 blood samples submitted by the police after traffic checks.

Analysis of the samples that tested positive for narcotics shows that THC (cannabis) is the most common drug (71 percent), followed by amphetamines like speed and ecstasy (30 percent), cocaine (15 percent), and GHB (6.8 percent).

The researchers analyzed not only which drugs were present in the blood samples but also their concentrations. The study covers the period from 2017 through 2023.

Of the suspects who tested positive, one in five combined two, three, or even four types of drugs. Most often, this involved the combination of THC with amphetamine or cocaine, or GHB with amphetamine.

Almost all arrested drivers were male (92 percent), with an average age of 29 years. Two out of three tested positive for the use of one or more drugs. Younger suspects under the age of 26 often had THC in their blood. The use of cocaine and amphetamine increases as drivers get older.

On July 1, 2017, the amended Road Traffic Act came into effect. Since then, the police have been using a saliva test, among other things, when there is a suspicion of drug use by a road user. Before 2017, the Traffic Act, which dates back to 1994, only stipulated that one was not allowed to drive after using drugs. In this version of the law, no threshold values were described by which it could be determined. Since 2017, the threshold values do exist. This is the first NFI overview of drug use in traffic since the new legislation.

The police’s saliva test indicates the presence of drugs and allows the police to take a blood sample from the suspect for analysis. The blood sample is sent ot a accredited toxicology laboratory where measurements are taken to determine which narcotics are present in the blood and in what concentration. These results show whether one or more drugs exceed the legal limit and whether there is a single or combined use of substances.

Follow-up research is planned, looking into drug-related accidents.