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.
The U.S. government defines hemp as any crop of cannabis containing 0.3% THC or less in dry weight.
THC (delta-9-tetrahydrocannabinol) is the substance in cannabis that confers a “high” and produces the subjective and cognitive effects that are typically synonymous with cannabis.
The 2018 U.S. Farm Bill legalized the production and sale of hemp, and now as a result, consumer hemp products, such as oils, vaping cartridges and hemp flowers for smoking can be legally purchased in specialty stores, general retail stores and through websites across the U.S.
Hemp is now increasingly finding use in medicine and wellness markets, particularly for its component CBD, short for cannabidiol, which is one of the more than 100 cannabinoids found in the cannabis plant.
According to New York-based investment bank Cowen & Co., the market for CBD last year ranged from $600 million and $2 billion in sales. Despite the size of this booming industry, it remains largely unregulated.
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.”
“Because the market for CBD products is so new and the popularity of use is growing so quickly, we want the public to be aware that a positive drug test is possible,” says Ryan Vandrey, Ph.D., associate professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
Vandrey and his collaborators at the University of Pennsylvania previously showed in a JAMA study that 21% of CBD/hemp products sold on the Internet contained THC, even though it wasn’t listed on the product labels. “I have a hard time finding anyone who hasn’t used a CBD product at least once, but most are completely unaware of the possibility of THC exposure or a positive drug test as a result of using these newly legalized products,” says Vandrey.
Trials demonstrated CBD to be an effective treatment for two rare forms of pediatric epilepsy, however, there is currently insufficient evidence to support use for any other health condition according to the U.S. Food and Drug Administration.
Despite this, CBD product suppliers and consumers claim benefits of CBD for a wide range of purposes, including everything from anxiety to insomnia to general wellness.
CBD products can be swallowed in the form of an oil/tincture, eaten in a food product (e.g., gummy bears), inhaled using “vape pens” similar to electronic cigarettes, or applied topically to the skin in a cream, patch, balm or gel.
For the current study, the researchers recruited three women and three men with an average age of 31 years old. One participant self-reported as African American and the rest as white.
The batch of cannabis used in this particular study contained 10.5% CBD and 0.39% THC, a 27 to 1 ratio of CBD to THC that is similar to what is often found in legal hemp/CBD products. In the study, research volunteers vaporized a little less than 1 gram of cannabis, which contained a total dose of 100 milligrams of CBD and 3.7 milligrams of THC. To vape the cannabis, heated cannabis vapor was collected into a balloon that was then inhaled by the participant.
Trials demonstrated CBD to be an effective treatment for two rare forms of pediatric epilepsy, however, there is currently insufficient evidence to support use for any other health condition according to the U.S. Food and Drug Administration.
In addition to vaping the high CBD/low THC cannabis, study volunteers also were given pure CBD in a capsule, vaporized pure CBD and placebo (a mock CBD pill and vaporized cannabis in which CBD and THC had been removed) in three other dosing sessions, one week apart from each other. In all active drug conditions (excluding placebo), the CBD dose delivered was 100 milligrams per session.
The drug testing cut-off used to determine a “positive” result in this study was a “screening” concentration of at least 50 nanograms per milliliter of THCCOOH, a metabolite used to indicate whether someone has used cannabis, in the urine sample using an on-site “dipstick” test. A positive on that test was then “confirmed” at a 15 nanograms per milliliter cut-off of THCCOOH using a more sensitive test method.
Two of the six participants who vaped the low-THC/high-CBD cannabis tested positive for THCCOOH.
No positive urine drug test results were observed in the other test sessions (pure CBD capsules, pure CBD vape or placebo).
“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.
The team says they plan to repeat their studies using products that fall within the current federal hemp regulations with respect to THC content, and additionally study the impact of repeated CBD/hemp exposure on drug testing outcomes.
Funding: This research was supported by SAMHSA and the National Institute on Drug Abuse (T32DA07209).
Other authors on the study were Edward Cone and George Bigelow of Johns Hopkins, David Kuntz of Clinical Reference Laboratory, John Mitchell of RTI International and Ronald Flegel of the Substance Abuse and Mental Health Services Administration (SAMHSA).
Cannabis Sativa is a plant species of Cannabis. In addition to its recreational use as a drug of abuse, the plant has widespread alternative uses including the production of food, cosmetics (hemp), textiles and medicinal applications1.
When toxicology laboratories are required to investigate past exposure to cannabis, analysis of hair can provide powerful evidence.
The compounds usually targeted for hair analysis to identify cannabis exposure are: Δ(9)-tetrahydrocannabinol (THC), the main active compound of cannabis, the metabolite [11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH)] and two cannabinoids (cannabinol (CBN) and cannabidiol (CBD))2. Typically passage of these cannabinoids into the hair includes passive diffusion from blood, diffusion from sweat/sebum or external contamination.
One of the key questions to be addressed when interpreting the results of cannabinoid hair analysis is that of proof of consumption. Are the results sufficiently clear to suggest cannabis was consumed, or could the results actually be the result of passive exposure to cannabis smoke, or other mechanisms? Passive exposure is defined by an individual being in an environment that is exposed to drugs, an important public health problem.
Cannabis smoke can be inhaled or absorbed into the hair by persons other than the intended smoker/user3.
Researchers have evaluated second-hand cannabis smoke exposure and the corresponding levels of cannabinoids in biological samples3,4. Herrmann et al. discovered that in unventilated, confined conditions cannabinoid detection was above threshold and higher concentrations of THC and THC-COOH were found predominantly in the blood, urine and hair4.
THC and THC-COOH have lower incorporation rates in hair in comparison to other bodily matrices.
The low presence of THC may be explained by its weak affinity to melanin while the acidic nature of hair may be the reason for the absence of THC-COOH5. Along with the levels of cannabis constituents detected in passive exposure, analysis has been conducted to understand what physiological impact exposure has3.
Past research has shown evidence of increased heart rate and minor impairments in coordination and memory4,6,7. Identification of THC/CBN/CBD in hair suggests exposure to cannabis, which could be due to low level or infrequent use of cannabis or historic or passive exposure. However, some argue that the presence of cannabinoids in hair, especially THC is indicative of repeated or chronic exposure5,8. The distinction between external contamination and consumption can be difficult for cannabinoid hair analysis9, and the implication of a positive test result can have significant consequences for the individual involved.
THC-COOH is only formed inside the body, and the presence of this gives unequivocal proof of consumption when detected in hair samples.
The metabolite has never been discovered in cannabis smoke ruling out environmental contamination10. With hair analysis, THC-COOH is detectable at very low concentrations.
The drawbacks for detection from this biological matrix are the requirement for expensive instrumentation and sample preparation can be a more time-consuming process when compared to urine11.
Routine laboratory screening of hair for cannabis varies and includes the detection of cannabinoids and/or THC-COOH8. Hemp is a variety of Cannabis Sativa and is closely related to Cannabis with the difference being in the percentage of THC12.
Hemp is grown for industrial use and found in food, lotions, medicines, clothing and construction materials. Hemp oil is extracted by pressing the seeds from the female hemp plant13.
The legalisation of hemp has caused controversy. This is because research has shown that the use or consumption of hemp products could have the potential to impact on drug testing for cannabis14.
Hemp oil products are advertised in health shops for their good source of omega fatty acids15. Bosy et al.16 assessed whether oral consumption of hemp oil would negatively affect existing drug screening protocols. Various oils were screened (THC content of bottled oils was 36.0, 117.5, 36.4, 45.7, 21.0, 11.5 mg/g) and administered to volunteers and their urine measured for metabolite levels. GC-MS analysis determined the amount of THC-COOH in each participant’s urine to be below the confirmation cut-off within a 48 hour cessation period.
Similarly to hemp oil, hemp foods are classified as ‘natural foods’ and are commercially available. Leson et al. showed that daily consumption of hemp food can lead to the presence of THC and THC-COOH in urine, but these compounds were below the confirmation thresholds17. T
hese authors16,17 suggest that hemp food and oil products do contain cannabinoids but in very low concentrations, and that ingestion of such products should not be deemed as a concern in drug testing. The Cannabis plant has been used in the production of cosmetics through the use of hemp oil and cannabis extracts18. A
n evaluation of Cannabio® shampoo revealed levels of THC, CBD and CBN, three constituents that indicate cannabis exposure19.
However, normal hygiene practice using the cosmetic produced no positive results in hair. Extreme use could generate positive results for CBN and CBD but not the primary constituent, THC.
Hemp oil is marketed as an effective cosmetic treatment for hair, with claims that direct application of the oil to hair has moisturizing benefits, can aid hair growth, may protect the hair and aid in damage repair, and the oil may add shine to the hair.
These claims are unsubstantiated but there is a substantial number of online retailers selling various hemp oil based products intended for direct application to head hair.
The composition of these products range from pure hemp oil, to hemp oil included at a relatively low concentration into shampoos and other hair treatments.
Source:
Johns Hopkins Medicine
Media Contacts:
Vanessa McMains – Johns Hopkins Medicine
Image Source:
The image is credited to Johns Hopkins Medicine.
Original Research: Closed access
“Urinary Pharmacokinetic Profile of Cannabinoids Following Administration of Vaporized and Oral Cannabidiol and Vaporized CBD-Dominant Cannabis”. Ryan Vandrey et al.
Journal of Analytical Toxicology doi:10.1093/jat/bkz080.
