Drinking a beer and then driving home – many people don’t see this as a big problem. Most people are still allowed to drive with a blood alcohol level of up to 0.5 per mille, and this is widely used. If cannabis can be consumed legally in Germany from Easter Monday, it is probably still far from clear what the new rules for weed-smoking drivers will look like. The currently valid value is based on the ban on the drug and on the fact that consumption can be reliably measured. It is one nanogram of the cannabis active ingredient tetrahydrocannabinol (THC) per milliliter of blood serum.
There are hardly any reliable rules of thumb for how long you have to wait after a joint in order to fall below this value, as many know for alcohol consumption. On top of that, the discussion about how it should be adapted for legal use is in full swing. Many experts advocate an increase because even at higher THC levels there is no impairment of the ability to drive.
Kirstin Zeidler, head of the insurer’s accident research, says: “We need clear rules for road traffic – ideally by April 1st for all road users.” For her, this also includes special rules for young and novice drivers. She is also calling for a ban on the mixed consumption of alcohol and cannabis, as this significantly increases the risk of accidents.
How dose and intoxication are related is not entirely clear
In the course of cannabis legalization, the so-called Limit Values Commission, which includes experts in forensic medicine, traffic medicine and toxicology, has been dealing with THC limit values for a long time. So far, however, it has not submitted any proposal for an adjustment. According to chairman Stefan Tönnes, a forensic toxicologist at the University of Frankfurt, there are many studies on the topic, but no clear recommendation can be derived from them.
Imke Groeneveld, project manager at the traffic police, writes that this can also be attributed to the fact that, unlike alcohol, it is not so clear how the dose or its concentration in the blood is related to the intoxicating effect of cannabis. The cannabis plant contains over 80 different cannabinoids, the effects of which are diverse. This makes a clearly defined limit difficult.
“A political decision”
In addition, experts point out that the THC concentration in the blood is increased for longer due to frequent consumption. For consumers who use a joint more than once a week, the one-nanogram limit can still be significantly exceeded even days after consumption without any impairment of driving.
Toxicologist Tönnes therefore referred the task of resetting the limit value back to politicians last summer: “There is a lot of sense of proportion or a political decision by weighing up various aspects behind it.”
Theresa Weiß Published/Updated: Recommendations: 7 A comment from Daniel Deckers Published/Updated: Recommendations: 88 Daniel Deckers, Berlin Published/Updated: Recommendations: 5
Federal Transport Minister Volker Wissing (FDP) has already reacted. He convened a new committee on the complex topic, this time it is now called the “Interdisciplinary Working Group”. However, their results are still pending. But that won’t happen until April 1st.