She and her colleagues at the University of Utah Health Sciences Center in Salt Lake City spiked three batches of urine samples with CBD, CBN and two other cannabis compounds -- cannabichromene and cannabigerol. The researchers tested each batch with two tests commonly used for THC screening. CBN reacted with one, while the other three compounds triggered no false-positives.
The tests are known immunoassays -- which means they use antibodies to detect drugs. Kroner explained that there are slight differences in the antibodies that test manufacturers use -- so it's possible to get different results. While the findings may be a relief to some CBD users, there is a big caveat: The researchers used pure CBD. In the real world, CBD products are largely unregulated and may contain other compounds due to processing. According to Robert Fitzgerald, a professor at the University of California, San Diego's Center for Advanced Laboratory Medicine, "It would depend on the purity of the product." On the positive side, he noted, immunoassays are only screening tests. They would be followed up by "confirmatory testing" that does distinguish THC from other compounds. But you could still have a problem if your cannabis product was contaminated with THC, Fitzgerald said.
Legally, Kroner noted, CBD products should only be produced from hemp plants with no more than 0.3% THC. But there's no way for consumers to know for sure what's in the products they buy. A 2017 study found that about seven out of 10 CBD products did not contain the amount of cannabidiol stated on the label. A false-positive on a drug test could have implications for people at work, and in their medical care. For example, some health care organizations do not allow patients to start opioid painkillers if they use marijuana. It all points to the importance of taking "cross-reactivity" into account when a drug screening test comes back positive, Kroner said. "Confirmatory testing should be done before any clinical decisions are made," she said. What should you do if you use any of these products and have a drug test coming up? The simplest course is to refrain for a while, according to Kroner. But she also advised being up front about your CBD or CBN use -- or any supplement use, for that matter -- so that your test results can be interpreted in that light. Kroner reported the findings Monday at the annual meeting of the American Association for Clinical Chemistry in Anaheim, Calif. Studies presented at meetings are generally considered preliminary until they are published in a peer-reviewed journal. Theoretically, CBD should not show up on a drug test. However, because most CBD products are classified as a supplement, it is not regulated for safety and purity. This means that contamination of the CBD with THC (tetrahydrocannabinol) may and does occur, and this may show up on a drug test, depending on the cutoff level of the test and other factors listed below. This is more likely to happen if the CBD you are buying is marijuana-derived CBD rather than hemp-derived CBD. Hemp-derived CBD is required by law to contain less than 0.3% THC, although regular daily ingestion of high doses of this may still cause THC to accumulate. Broad-spectrum CBD is also less likely to be contaminated with THC. This is because all the THC is removed in broad-spectrum CBD as opposed to full-spectrum CBD which contains all of the compounds that naturally occur in the plant they were extracted from. CBD isolate is also pure CBD, and typically comes from hemp so it shouldn’t contain THC. If you want to pass a drug test, don't take CBD; or if you are taking it legally within your State's laws, then declare it (however it still may be contaminated with THC unless brought by a reputable supplier who guarantees it to be THC-free). How much THC needs to be present to cause a positive drug test? It is difficult to say how much THC needs to be present to cause a positive drug test because this depends on several drug and patient-specific variables, and also the cutoff value for the test. The following variables affect the amount of time that marijuana (THC) and its metabolites remain detectable in the urine or other biological samples: Frequency of marijuana use (the half-life of THC is 1.3 days for an infrequent user and 5-13 days for frequent users) Presence of interacting drugs How much is used and the route of administration Last time of ingestion. Several patient factors can also affect the result, such as body mass, urine pH, urine concentration and other medical conditions such as kidney or liver disease. An estimate of the length of time marijuana (THC) is detectable in urine is: Single-use: 3 days Moderate use (4 times/week): 5 to 7 days Chronic use (daily): 10 to 15 days Chronic heavy use: More than 30 days.
Federal workplace cutoff values for marijuana metabolites are 50 ng/mL for immunoassay screening tests (one ng is a billionth of a gram). In a confirmatory test, a metabolite of marijuana is measured, called delta-9-tetrahydrocannabinol-9-carboxylic acid, and a positive test result is above 15 ng/mL.
However, this can vary depending on the variables listed above and should not be relied upon to ensure a drug-free result. Despite the widespread use of urine drug tests, there appears to be some inconsistency in the interpretation of test results. Considering the significant consequences a false-positive result can have (such as loss of job or imprisonment), this is somewhat surprising.