Rockville, MD: Marijuana consumers are likely to experience frequent spikes in their level of detectable metabolites despite having ceased using the drug, according to clinical trial data published in the October edition of the Journal of Analytical Toxicology.
Investigators at the National Institutes of Health performed urine screens for the presence of the carboxy-THC metabolite (aka THC-COOH, the most commonly screened for metabolite in workplace drug tests) in 60 adult cannabis users for a period of 30 days. Participants in the study resided in a closed research unit during the trial period and abstained from any use of cannabis during their stay.
Researchers reported that subjects frequently experienced spikes in the levels of detectable metabolites in their urine despite having abstained from the drug for several days or weeks.
“During the terminal elimination phase, an individual may produce consecutive specimens that test positive, negative, and positive again over time,” authors concluded. “This makes it problematic to determine whether positive results are indicative of new drug use or reflective of previous cannabis exposure.”
Authors reported that heavy users were more likely than moderate users to have their metabolite levels fluctuate below and above the test’s detection cut-offs on consecutive days.
Responding to the study, NORML Deputy Director Paul Armentano said: “This study has major implications for virtually every marijuana consumer, particularly those who are facing drug testing as a requirement of parole or probation.”
Armentano said that many probation officers and judges interpret any increase in carboxy-THC levels as per se evidence that the defendant has reinitiated their marijuana use and violated the terms of their probation.
“In fact, however, former marijuana users will frequently see their metabolite levels dip and then rise again over time,” he said. “This result is simply a result of the complex manner by which the human body eliminates carboxy-THC. These temporary spikes do not prove that a defendant has recently used marijuana, and these results do not warrant revoking one’s parole or sending them to jail.”
For more information, please contact Paul Armentano, NORML Deputy Director, at: paul@norml.org. Full text of the study, “Urinary elimination of 11-nor-9-carboxy-tetrahydrocannabinol in cannabis users during continuously monitored abstinence,” appears in the Journal of Analytical Toxicology.