¿La presencia de cannabis en saliva es suficiente para confirmar la conducción bajo sus efectos?

Abstract

In Spain today, the presence of drugs in saliva is considered sufficient to confirm driving under its effects, although the concentration obtained is near the threshold limits of the analytic system. This legal approach entails accepting that there is no concentration threshold below which the drug does not affect driving capacity, and that oral fluid concentration is a reliable parameter to value its effect. In the case of cannabis, some experimental studies in humans and in intercepted drivers have suggested blood tetrahydrocannabinol concentrations from which effects that can affect driving are observed. Furthermore, correlation between tetrahydrocannabinol concentration in oral fluid and in blood shows a high variability. To resolve disagreement between these types of samples, some countries have harmonized their legislation establishing presumptive oral fluid cannabis values at the same time as blood concentration limit values from which it can be clearly considered that driving capacities are affected. In this work, we consider that the Spanish road safety law should, following trends adopted by other countries, establish a limit value for cannabis and other abused drugs, which allows evidence that the driver has not only consumed the drug, but is also driving under its effects.