The curve would also go down very rapidly, and within 60 minutes. Within one hour, the levels of THC could be below 10 nanograms, or even five nanograms.
This is all perfectly monitorable in a laboratory setting. It means that we have been able to link certain levels of impairment to certain levels of THC in blood, as well as in oral fluid. This works fine. All of the results that come from these studies will indicate two nanograms, for example, which is really the lower limit above which impairment levels become apparent.
If we want to transfer this knowledge to real life and practice, the levels that people like me are measuring in the laboratory are not necessarily identical to the levels that a policeman, for example, would observe, or a forensic laboratory when analyzing the blood samples. The main reason is that the blood samples after an actual crash are usually taken two hours, three hours, or even four hours after the accident occurred.
This is the big dilemma that we are facing right now. The levels that we measure are representative of the THC concentration at the time that the blood sample was taken, but not necessarily at the time of the actual crash. This is a bridge that we need to cross somehow. It is important to keep in mind that with the majority of people who will be involved in a crash for which a blood sample will be taken two hours, three hours, or even later, after the crash, the majority of these samples will show very low THC limits. They may be well below one nanogram, or below two nanograms. That does not necessarily mean that all of these drivers were negative or under the THC threshold at the time of the crash.