There is a major, ongoing debate in relation to the safety of cannabidiol (CBD) in over the counter products. Can the safe and non-psychotropic CBD, which is the basis of these products, chemically transform into a psychotropic cannabinoid such as tetrahydrocannabinol (THC)? If so, under what conditions would this happen?
Cannabidiol (CBD) is a non-psychotropically active component of the Cannabis plant. However, CBD is, in chemical terms, very similar to its psychotropic “cannabinoid cousins”, of which delta-9-tetrahydrocannabinol (THC) is the most famous. The two compounds share the same chemical composition but in different arrangements. They are both cyclic compounds, with their atoms forming a ring, but CBD has an open ring, while THC has a closed ring structure.
The shape of the compound determines how it can connect to endocannabinoid system receptors and result in a psychotropic effect.
A concern for researchers and regulators is whether the CBD present in over the counter products can degrade or chemically transform back into a psychotropic form. If this occurred, it would have profound implications for the safety, regulation, and the future legality of CBD products.
With the growth of CBD products on the market, in a variety of forms (liquid, oils, tablets, etc.), the issue of whether CBD can change due to storage conditions has become of greater interest. As already discussed, storage under acid conditions can encourage chemical transformation into D9-THC. Such conditions may be present in vaping liquids, many of which are the products of poor manufacturing and have dubious quality. Similarly, high temperatures can convert CBD to D6-CBD, which has shown THC-like effects in Rhesus Monkeys.
Exposure to light, UV light exposure, oxygen, and a variety of solvents also generally encourages CBD decomposition. However, none have yet been associated with increased D9-THC or other psychotropic derivatives. It appears that CBD conversion into D9-THC may occur after extended decomposition processes. It also appears though that the decomposition rate of D9-THC is rapid and is not present in high quantities as it decomposes to cannabinol. Although this decomposition process still produces potential psychotropic compounds, this only occurs in very extended storage conditions far longer than would be normal for typical CBD product storage.
In early research on CBD’s psychotropic effects on animals, some psychotropic effects became known, but only at very high doses (compared to relatively low doses with THC). Both compounds showed increased activity after hydroxylation, a chemical process that adds a hydroxyl (O-H) group onto the chemical structure. This process is the first step of chemical oxidative degradation of organic compounds in the presence of air.
Research has conclusively found that CBD is non-psychotropic in its original form. However, many studies have investigated whether compounds resulting from the chemical conversion of CBD, perhaps during storage of the product over time, may themselves be psychotropic.
The conversion of CBD to THC or other cannabinoids typically requires an acidic environment or high temperatures. Under these conditions, CBD can convert into a range of cannabinoid compounds, including D9-THC, D7-THC, D8-THC, D10-THC, D11-THC, and iso-THC, plus various compounds resulting from the hydroxylation of CBD (e.g., 11-hydroxy-CBD).
In addition, the presence of ethanol or methanol can also aid conversion. However, it is worth noting that nearly all the research on conversion of CBD has taken place in test tubes rather than live animals.
The finding that acidic conditions facilitate CBD conversion raised the inevitable question if the acidic gastric juices in the stomach can trigger this conversion? A small number of studies have examined this question in the laboratory using artificial gastric juice, but have proven to be controversial.
Three studies found that CBD converted to a number of psychotropic compounds, including D9-THC, when being in the presence of artificial gastric juice for 20 hours. Critically, however, scientists have not been able to replicate these results in live animals. Experiments monitoring CBD urine and plasma levels in dogs, rats, and humans have not found any notable conversion products after taking CBD.
Nevertheless, the debate continues, with some researchers pointing to the conversion of CBD in acidic conditions (like stimulated gastric juice) as good evidence for further studies. Others, however, remain convinced that laboratory conditions do not replicate real stomach conditions and no real-life examples exist. Further research studies continue to question their validity and procedures. Of absolute importance, however, is that researchers use highly pure CBD, otherwise traces of THC or THC contamination may be present in their extracts, which would perhaps explain the occasional positive findings.
Laboratory results undoubtedly provide some evidence that CBD can decompose into psychotropically active compounds such as D9-THC (in the presence of synthetic gastric juices). However, it remains a point of ongoing scientific debate whether these results translate to real-world conditions. The current evidence from animal studies has not shown any reliable evidence of CBD conversion to D9-THC measured in the blood or plasma. In addition, oral CBD given to humans similarly showed no measurable psychotropic compounds in the body at levels that would be of concern.
The second safety concern is the conversion of stored CBD to D9-THC (or other psychotropic cannabinoids) in pre-consumed CBD products. Research found that under specific storage conditions, CBD could convert to D9-THC, although it appears to require unusually long periods of time. Nevertheless, the findings highlight the need for manufacturers to pay attention to packaging and storage conditions in order to eliminate any possibility of degradation occurring.
In the longer-term, manufacturers may want to consider testing the addition of compounds that would reduce or slow-down decomposition, as seen in some food products.
Golombek P, Müller M, Barthlott I, Sproll C, Lachenmeier DW. Conversion of Cannabidiol (CBD) into Psychotropic Cannabinoids Including Tetrahydrocannabinol (THC): A Controversy in the Scientific Literature. Toxics. 2020 Jun 3;8(2):41. doi: 10.3390/toxics8020041. PMID: 32503116; PMCID: PMC7357058.