According to a study just released by the American Association of Clinical Chemistry, chronic pot smokers can test positive for residual levels of THC in blood for up to several weeks after abstaining from smoking marijuana. The study is based on findings from 30 daily pot smokers who smoked ten joints per day and then stopped smoking while researchers tested their blood.
"Of the 22 subjects tested 24 hours following admission into the trial, 12 (59 percent) tested positive for THC levels greater than 1ng/ml, but none tested at levels greater than 5ng/ml," the study states. "All of the subjects' THC/blood levels tested below 1ng/ml within seven days following admission."
Despite that, researchers found that the amount of THC in the blood of participants "did not always decrease in a consistent manner" and "one subject continued to test positive for trace levels of THC for a total of 33 days."
While the results aren't exactly shocking, apparently this is the first medical study to report on THC levels in chronic pot smokers who remained abstinent in a monitored, i.e. controlled environment for such an extended period of time and still tested positive for THC.
It'll be interesting to see how these findings impact hearings scheduled for April 23 on State Senator Lou Correa's proposed bill, SB289, which would outlaw driving with any detectible amount of marijuana in your blood unless you have an actual doctor's prescription. Already, NORML is fighting the bill because of the possibility that folks who smoked a doobie a few weeks ago could get charged under the new law if they fail a blood test.
"According to the US National Highway Traffic Safety Administration," NORML points out. "It is difficult to establish a relationship between a person's THC blood or plasma concentration and performance impairing effects . . . It is inadvisable to try and predict effects based on blood THC concentrations alone."