The government is proposing that the lowest level offence apply to drivers who test between two and five nanograms of THC per milliliter of blood. If a driver tests higher than five nanograms or has a blood alcohol concentration greater than 50 milligrams per 100 ml, they will receive the penalties for drunk driving under the Penal Code, which includes imprisonment for recidivism. Urinary concentrations of 11-NOR-9-carboxy-THC tend to increase over a 10-day period, which is important in abstinence tests. The new per se THC limits would allow police to file charges immediately based on blood test results. Table 2 does not include data on drivers with both alcohol and THC in their system.
In an experiment, joints contained 200 mg of cannabis with THC concentrations of 0.94% and 0.8%, and CBD concentrations of 23.5% and 17% for untreated smokers and chronic smokers, respectively. 9_THC is usually stored in basic or organic solvents in amber silicate glass containers to prevent its loss during analytical procedures. A high blood THC level is a good indicator of being under the influence of marijuana, but it is not infallible. The hydroxylation of 9-THC produces the psychoactive compound 11-hydroxy 9_Tetra hydrocannabinol (11-OH-THC), and subsequent oxidation generates the inactive 11-nor-9-carboxy-9-tetrahydrocannbinol (THCCOOH). While alcohol concentration (BAC or BrAc) is an accurate measure of alcohol deficiency while driving, the presence of THC in the driver's body has not been shown to be a reliable measure of marijuana driving impairment. Urinalysis does not detect the psychoactive component of marijuana, THC (delta-9-tetrahydrocannabinol), and therefore do not measure deterioration; rather, they detect the non-psychoactive metabolite of marijuana, THC-COOH, which can remain in the body for days and weeks without harmful effects.
The maximum THC level can occur when the deficiency is low, and the high deficiency can be measured when the THC level is low. The North Carolina State Crime Laboratory also analyzes the metabolites 11-hydroxydelta-9-tetrahydrocannabinol (11-OH-THC) and 11-nor-delta-9-tetrahydrocannabinole-9-carboxylic acid. Upon assimilation through the blood, 9-THC rapidly penetrates fatty tissues and highly vascularized tissues, including the brain and muscles, causing a rapid decrease in plasma concentration. However, the bioavailability of 9-THC varies depending on the depth of inhalation, the duration of inhalation and the retention of respiration. Some individual signs, symptoms and tests had a weak correlation with THC levels being above or below a certain threshold, but none of them reached basic sensitivity levels to correctly predict impairment. NHTSA publications contain additional information about this topic, but it is not possible to determine altered interpretation based on blood concentrations of THC and its metabolites.