Research continues to prove what many have been saying for years: cannabis can stay in the system for a long time after the substance was used, and therefore cannabis blood tests are not a fair way to tell if someone has just used cannabis.
A new study titled “Residual blood THC levels in frequent cannabis users after over four hours of abstinence,” which appeared in the Drug and Alcohol Dependence journal, provides more evidence that alcohol can stay in the bloodstream long after a high has passed or after cannabis has been used. The study was conducted by researchers affiliated with the University of British Columbia, and then their results were published in an official study.
“Some stakeholders worry that current per se limits may criminalize unimpaired drivers simply because they use cannabis,” the researchers explained. “We conducted a systematic review of published literature to investigate residual blood THC concentrations in frequent cannabis users after a period of abstinence.”
So far, the study shows that if more than 2ng/ml are detected in the blood from cannabis use, they can persist for an extended period of time, so it’s not fair to look at that amount in the bloodstream and claim