“These results suggest that pure CBD, used once by itself, will not cause a positive drug test,” says Vandrey. Adding to this, Spindle points out that it “does not take much THC exposure to trigger a positive test for some people.” There may be variation from person to person in drug metabolism and puffing behaviors such as inhalation depth, which might contribute to the breakdown or buildup of cannabinoids in the body, the researchers say.
In a study of six adults, Johns Hopkins Medicine researchers report evidence that a single vaping episode of cannabis that is similar in chemical composition to that found in legal hemp products could possibly result in positive results on urine drug screening tests commonly used by many employers and criminal justice or school systems.
In a paper published Nov. 4 in the Journal of Analytical Toxicology, the researchers report that two out of six study participants tested positive after vaping cannabis that contained 0.39% THC using urine testing methods that are consistent with testing frequently performed for employment-related or criminal justice-related urine drug testing programs. Though the cannabis used in this study does not currently meet the federal definition of hemp, the THC concentration of 0.39% exceeds federal regulation by just 0.09%.
“People who use legal hemp products for medical intent rarely just use them once as we did in this study, and prior studies show that THC and its metabolites may accumulate with repeated use,” says postdoctoral fellow Tory Spindle, Ph.D., a researcher in the Behavioral Pharmacology Research Unit at the Johns Hopkins Bayview Medical Center. “What this means is that people need to be wary of single-dose or cumulative THC exposure and be aware that these now legal products may cause an unexpected positive result on a drug test.”
Two of the six participants who vaped the low-THC/high-CBD cannabis tested positive for THCCOOH.
Over the past several years, FDA has issued several warning letters to firms that market unapproved new drugs that allegedly contain cannabidiol (CBD). As part of these actions, FDA has tested the chemical content of cannabinoid compounds in some of the products, and many were found to not contain the levels of CBD they claimed to contain. It is important to note that these products are not approved by FDA for the diagnosis, cure, mitigation, treatment, or prevention of any disease. Consumers should beware purchasing and using any such products.
Mr. Pennington was despondent about possibly losing custody of his child, until he spoke with Frank Conrad, the chief technology officer and lab director at Colorado Green Lab, a scientific consultant to the cannabis industry. Mr . Conrad directed him to 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. In short, the drug testing lab may have erred; it was entirely possible that the CBD Mr. Pennington had given his child had caused the drug test to produce a false positive for THC.
Bruce Houlihan, director of the Orange County, Calif., crime lab and chair of the emerging drugs and opioids committee for the American Society of Crime Lab Directors, expressed concern. “If any labs are using this method, they’ll have to be careful,” Mr . Houlihan said. He added that there was no way to estimate how many drug testing labs might be accidentally mistaking CBD for THC, because forensic labs generally determine their methodology in house.
By Amanda Chicago Lewis
Elizabeth has been in touch with Mr. Conrad, but he is not serving as a witness in her case.
“I was mortified,” Mr. Pennington recalled recently. “My jaw hit the floor. I just knew from the bottom of my heart I hadn’t gotten any THC in my son’s system.”