New NIDA Study: THC Blood Levels Do Not Accurately Measure Intoxication

marijuana card

New NIDA Study: THC Blood Levels Do Not Accurately Measure Intoxication

A new study from the National Institute on Drug Abuse has offered revealing information on the perceived correlation between cannabis consumption rates and THC blood concentration levels.Gloved-hands-with-blood-vial-300x200

Researchers examined the blood and plasma levels of both frequent and occasional cannabis consumers, before and after smoking. Frequent and occasional smokers resided on a closed research unit and smoked one 6.8% THC cannabis cigarette. Blood and plasma cannabinoids were quantified on admission (approximately 19 hours before), 1 hour before, and up to 15 times (0.5–30 hours) after smoking.

The results showed that, “Cannabinoid blood and plasma concentrations were significantly higher in frequent smokers compared with occasional smokers at most time points for THC and 11-OH-THC and at all time points for THCCOOH and THCCOO-glucuronide.” Results were the same regardless of participants’ baseline concentration levels, or, how much THC was in their blood when the study began.

Researchers also found that the median time blood THC levels over 5 ng/ml were detectable was 3.5 hours in frequent smokers (ranging from 1.1 – 30 hours),  and 1 hour in most occasional smokers (ranging from 0 – 2.1 hours); 2 individuals never tested over 5 ng/ml.

These results show a drastic difference in the amount time THC lingers in the blood of participants – not based on the amount of cannabis consumed, but on the frequency of their cannabis use.

Delta Extrax

This information is so important because many states in the U.S. have implemented drugged driving laws for cannabis based on a ng/ml level – including both Washington and Colorado, where recreational cannabis is now legal, and the standard measurement rendering a driver guilty of a cannabis DUI is 5 ng/ml.

Steering-Wheel-630x452The findings in this study indicate that people who consume cannabis more frequently are significantly more at-risk of being found guilty of a DUI, regardless of how long ago or how much they smoked, simply because THC lingers in their blood notably longer than those who consume cannabis occasionally or rarely.

Common sense and educated inference would indicate that a seasoned smoker would not, however, be rendered more intoxicated than a first-timer, or occasional smoker who consumed the same amount – therefore reaffirming the determination that intoxication from cannabis cannot be accurately measured by THC blood content.

The study, e-published ahead of print in the February issue of Clinical Chemistry, concludes by stating that, “Cannabis smoking history plays a major role in cannabinoid detection. These differences may impact clinical and impaired driving drug detection.”

– TheJointBlog


  • tony prosser
    February 27, 2014

    what about all the people driving around out of their heads on prozac ?

    • Mike B
      March 1, 2014

      What about people on Prozac? THIS article was, quite clearly, about pot. Marijuana. Weed. Definatly not Prozac.

    • Wendy
      March 2, 2014

      To you Tony,
      Please do not give us people who happen to take Prozac, drive a car, and quite regularly smoke marijuana a bad name by being a DUMMIE!!!! This is a marijuana blog, not pill popping, driving a car, and possibly who knows what…just sayin…and btw…before you have some snappy comeback, I am smart, 139 IQ smart, and 6 years of college, as well as bipolar, PTSD, and chronic major depressive disorder, so yes, I take Prozac, among a couple of other anti depressant, anti-psychotic meds, smoke weed occasionally, and drive my damn car….will not drink and drive though….;^D
      It totally impairs me.

  • Jordan
    March 1, 2014

    That’s not what he was referring to, it’s the double standard that if you meds are prescribed by a doctor it’s fine, but if you go out side the system then your a target.

    • Mike
      May 27, 2014

      Jordan is right. Prozac alters your brain so driving on it shouldn’t be allowed at all. Whether or not you are used to it as a prescribed medication does not matter because it still impairs you. Marijuana, on the other hand, does not impair you. The fact that you can get the same charge as a DUI is ridiculous. I am a safer driver when I am stoned because I drive more cautiously and have no need to rush.

      So you have all these conditions and that means you need to take Prozac? Well guess what, I have the same problems Wendy, including spinal injuries and I do not take any mind altering Pharma drugs. Sure that’s what the doctor prescribed me and beyond with all the pain killers, but I don’t take them because I know they impair me, especially enough to make my driving suffer even though racing is what I do for a hobby.

      I am an excellent, conscious driver, but pharma drugs impair my ability to react and stay fully aware. Therefore, they will affect anybody in a worse way for driving, whether you think it does or not. Most likely, you are not such a great driver to begin with because 90% of the people on the road don’t understand physics, braking, or turn signals. It is the difference between people with their mind altered, unaware, in comparison to people with a subtle buzz going that actually makes them more aware and attentive on the road. Which is more unsafe?

Post a Comment