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Updated: Jul 11, 2026
06:09
Development of a Preclinical Inhalation Model to Test Vaporized Cannabis Distillates
Published on: May 30, 2025
Developing limits for driving under cannabis.
Franjo Grotenhermen1, Gero Leson, Günter Berghaus
1Nova-Institut, Hürth, Germany. franjo.grotenhermen@nova-institut.de
Addiction (Abingdon, England)
|October 6, 2007
Summary
Establishing a delta-9-tetrahydrocannabinol (THC) blood limit is crucial for traffic safety. Research suggests a THC limit between 7-10 ng/ml may indicate impairment comparable to a 0.05% BAC.
Area of Science:
- Forensic Toxicology
- Traffic Safety Research
- Cannabinoid Pharmacology
Background:
- Cannabis use presents challenges for traffic safety due to potential impairment.
- Establishing objective measures for impaired driving is essential for public health and safety.
Purpose of the Study:
- To develop a rational and enforceable basis for controlling the impact of cannabis use on traffic safety.
- To evaluate evidence for setting per se limits for delta-9-tetrahydrocannabinol (THC) in drivers.
Main Methods:
- An international expert working group convened to review evidence.
- Evaluation of experimental and epidemiological research on cannabis and driving.
- Discussion of approaches to developing per se limits for cannabis.
Main Results:
- Finite, non-zero per se limits for THC in blood are proposed as the most effective approach.
- Epidemiological data suggest THC concentrations below 10 ng/ml are not linked to increased accident risk.
- A serum THC concentration of 7-10 ng/ml correlates with impairment similar to a 0.05% blood alcohol concentration (BAC).
Conclusions:
- The analysis provides an empirical basis for a preliminary per se THC limit.
- This limit aims to identify drivers impaired by cannabis use.
- Further epidemiological data are needed to refine the proposed THC limit.
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