We have covered the continued issues with measuring THC in the body, more specifically, determining whether someone is impaired based on a given THC reading. In addition to not being able to find the benchmark for impairment from using marijuana, it seems like some of the machines used to measure the drug in the body can’t tell the difference between THC and CBD.
CBD, or cannabidiol, and THC, or tetrahydrocannabinol, are both naturally occurring compounds in both cannabis and hemp. Traditionally, the concentration of CBD found in hemp is higher and marijuana has a higher concentration of THC. Although they have the same molecular structure, a big difference between the two is that CBD lacks the psychoactive component that THC is most widely known for. And for purposes of a DUI, a person cannot get a DUI with CBD in their system because it would not cause someone to become so impaired that they are unable to operate a vehicle as a sober person would.
Also, while cannabis or marijuana is only legal in some states and not federally accepted, the passing of the Farm Bill of 2018 federally allowed the growth and sale of industrial hemp. With the legalization of hemp came a wide variety of CBD products which claim to offer assistance with anxiety or insomnia, however, the FDA only has approved one drug that contains CBD, which aids in treating a rare form of epilepsy.
Now, as mentioned above, hemp and marijuana both carry trace amount of both compounds. So while processed hemp, or CBD, products may not list THC as an active ingredient, it is possible that trace amounts of it show up on a blood test, or depending on the test conducted, the presence of CBD could be mistaken for THC.
Such was the case for Mark Pennington. Pennington, a divorced father who was sharing custody of his 2 year-old son, was informed by the mother of the child that his custodial rights were going to be taken away because she had run a drug test with the son’s hair and the test came back positive for THC, which could only have been during the time that the child was in his custody. Pennington had no recollection of giving his son anything containing THC and did not recall using the substance near his son. He was later advised of “a little-known study published in 2012 in the Journal of Analytical Toxicology that showed that a common forensic drug testing method could easily mistake the presence of CBD for THC,” by Frank Conrad, a scientific consultant who acted as his expert witness.
The notion that a drug test can misidentify the presence of THC is terrifying, especially given the problems we continue to encounter (and write about) with regards to determining intoxication.
The studies that Conrad referred to in his testimony deal with those that are run through the gas-chromatography mass spectrometry machine (GC-MS). Not all tests that are run through this chemical analysis unit are the same. Certain substances must be combined with a chemical in a process called derivatization. Commonly, the tests are run with a chemical called trifluoracetic anhydride (TFAA). The 2012 journal article found that when the GC-MS used TFAA to run its tests, it was unable to distinguish between CBD and THC, resulting in a report with the presence of THC.
Not all tests are derivatized with TFAA, but it is the most common derivatizing agent. Now, many labs have upgraded their testing to the use of high-performance liquid chromatography, which is less likely to make the distinguishing error between CBD and THC, but there are still many that rely on GC-MS technology.
As if there wasn’t enough to worry about in the way of law enforcement and prosecution getting the “damning” information correct.