Road Safety: increase in blood concentrations of cannabinoids between 2010 and 2013 – assessment of confirmation tests

In 2008, the French government decided to set up oral-fluid drug screening in drivers. This new practice modified the customs of police officers and the number of screenings and confirming tests increased dramatically. Since this change, we have consequently observed an increase in blood concentrations of cannabinoids without any modifications in our lab procedures. In trying to understand this rise and to confirm this observation, we extended our study to include another lab. Results were reviewed by both LAT LUMTOX lab and FSIFG’s forensic toxicology unit and data was obtained between 2010 and 2013 for the following substances: Δ9-tetrahydrocannabinol (THC), 11-nor-9-carboxy-THC (THCCOOH) and 11-hydroxy-THC (11-OHTHC). Results were classified as “nondetected”(ND), “detected” (D) and “quantified” (Q) and if no substance was detected, results were considered negative (NEG). Parametric statistics were carried out using χ² tests and ANOVA-1 performed with GraphPad Prism 5.0® software. Since 2010, the number of NEG has still been stable (ns) when the proportions of D and Q changed significantly. Significant increases in blood concentration of all cannabinoids were also observed (e.g. LATLUMTOX for THC from μ2010=3.40±0.14 ng/mL to μ2013=5.26±0.10 ng/mL, p