ACMD Sets THC Limit to 50 µg per Single Serving

In the UK, the THC limit in consumer products is set to 50 µg per single serving. On Friday, 17th December, the Advisory Council on the Misuse of Drugs (ACMD) published a report on consumer cannabidiol (CBD) products.

In the report, the ACMD issued the recommendations for the appropriate levels of THC and other controlled phytocannabinoids in individual servings of CBD, suggesting that the dose of each controlled phytocannabinoid should not exceed 50 micrograms per unit of consumption. The unit of consumption is defined as a ‘single serving’ or the typical quantity of a CBD product consumed on one occasion.

The ACMD was commissioned in January 2021 to advise the British government on establishing a legal framework for consumer CBD products. Since then, the ACMD’s Working Group has reviewed the literature, consulted with industry and analytical laboratories, issued a public call for evidence, and sought information regarding testing from the Government Chemist’s Team and Defence Science and Technology Laboratory (Dstl).

They found that the relatively unregulated nature of the market has led to dramatic differences in actual levels of ∆9-THC in different products coming from different suppliers. A Dstl investigation into 43 commercial CBD products available in the UK found that 16 (37%) of them contained more than 5 mg of ∆9-THC.

Currently, the most commonly sold CBD product in the UK is CBD oil. However, in this report, the ACMD underlines that the range of consumer products derived from Cannabis is rapidly changing, with new products coming to market containing other uncontrolled phytocannabinoids such as cannabichromene (CBC) and cannabigerol (CBG).

The Council has decided not to recommend a single concentration limit for all CBD consumer products due to the different routes of administration.

THC limit: Ten conclusions

The Council has reached the following conclusions:

• Extraction of controlled phytocannabinoids from consumer CBD products is unlikely to be a viable means of obtaining these drugs for illicit use.
• It would be appropriate to set specific limits for the content of ∆9-THC and its precursor ∆9-THCA (i.e. ∆9-THCA-A and ∆9-THCA-B) in consumer CBD products.
• Plant-derived consumer CBD products would not contain sufficient controlled phytocannabinoids (other than ∆9-THC) or their precursor acids to produce any pronounced psychoactive effects unless they were added to the product (i.e. spiked). To prevent the possibility of spiking a limit should be set for all controlled phytocannabinoids in consumer CBD products.
• The dose limit for a total ∆9-THC (∆9-THC plus ∆9-THCA) should be set for all controlled phytocannabinoids in consumer CBD products.
• The dose limit for the total ∆9-THC (∆9-THC plus ∆9-THCA) should be 50 micrograms (µg) in a unit of consumption (where a unit of consumption or ‘single serving’ is the typical quantity of a CBD product consumed on one occasion).
• At the recommended levels the controlled phytocannabinoids present in
consumer CBD products are highly unlikely to produce any harmful effects.
• Setting a single concentration limit that applies to all consumer CBD products would not be appropriate.
• Further research is needed to confirm whether conversion of CBD to ∆9-THC by extreme heating can occur and its relevance to the processes involved in CBD vaping evaluated.
• Currently the methods for extraction, separation, and quantification of controlled phytocannabinoids in consumer CBD products are not sufficiently robust with regards to sensitivity, accuracy, and reproducibility.
• Laboratories assessing compliance should be accredited to the ISO standard and producers should use laboratories which hold that accreditation to perform their quality assessment testing.

THC limit: Four legal framework recommendations

To provide a legal framework under the Misuse of Drugs Act 1971, the ACMD has made these four recommendations:

Recommendation 1

That the total dose of ∆9-THC (including ∆9-THCA, as calculated using Equation 1 in the report) and all other controlled phytocannabinoids in consumer CBD products be controlled. The dose of each controlled phytocannabinoid should not exceed 50 micrograms (µg) per unit of consumption.

Note 1. A unit of consumption or ‘single serving’ being defined as the typical quantity of a CBD product consumed on one occasion.

Recommendation 2
That regulatory authorities ensure that any consumer CBD product permitted to the market has limits on the content of controlled phytocannabinoids such that the dose of ∆9-THC (including its precursor ∆9-THCA) and of each of the other controlled phytocannabinoids does not exceed 50 micrograms (µg) per unit of consumption.

Recommendation 3
A further inter-laboratory comparison trial (ring trial) should be commissioned specifically to support the capability of testing laboratories to detect controlled phytocannabinoids below the recommended maximum levels in a representative range of consumer CBD products

Recommendation 4
That development of more accurate testing for controlled phytocannabinoids is supported (as outlined in Notes 1 – 3 below) to allow testing capabilities to develop and be fully regulated.

Note 1: Standardised protocols should be developed for the extraction, separation and quantification of controlled cannabinoids (and their precursor acids) from consumer CBD products. These must be of sufficient reproducibility and sensitivity to be appropriate for the measurement of the level of controlled phytocannabinoids as
recommended in this report.

Note 2: As chemical reference standards are not currently commercially available for all controlled phytocannabinoids, suppliers of chemical reference materials should be encouraged to produce certified standards for those controlled cannabinoids for which standards are not currently available.

Note 3: ACMD supports the recommendation from the Dstl report (Defence Science and Technology Laboratory report, 2020b) that the analytical methods used should be accredited to ISO 17025:2017 to ensure appropriate method validation, quality control, and independent assessment of the methods.

The psychoactivity of the cannabinoids

With the written submissions received to their Call for Evidence and in international food regulations, the ACMD determined that the recommended lowest-observed-adverse-effect level (LOAEL) for ∆9-THC ranges between 2 – 5 mg/day. The Council’s Working Group considered that a ∆9-THC dose of 1 milligram (mg) was unlikely to produce significant psychoactive effects.

Based on the present scientific evidence, the Council found that the possible attenuating or exacerbating effect of CBD on the behavioral and cognitive effects of ∆9-THC can not occur at the doses of CBD available from consumer products in the market. They have found no firm evidence that minor cannabinoids or terpenoids present in preparations could act synergistically to enhance the effects of ∆9-THC nor interact with CBD to induce an acute psychoactive effect.

The 2016 ACMD’s Phytocannabinoids report found sufficient evidence to determine the psychoactivity of ∆9-THC, delta-8-tetrahydrocannabinol (∆8-THC), and CBN. It was unsure about the psychoactivity of delta-9-tetrahydrocannabivarin (THCV). For the remaining eight out of twelve controlled phytocannabinoids, there was not sufficient evidence to determine psychoactivity.

Scientific evidence shows that oral administration of CBN produced no psychoactive effects at a dose of 50 mg. A study comparing single intravenous doses of ∆9-THC, CBN, and CBD found that the dose of CBN required to produce subjective psychoactive effects was over 10-fold higher than that for ∆9- THC.

While the precise thresholds for psychoactive effects from ∆8-THC, THCV, and CBN may not be possible to estimate, the Council found that it can be concluded with reasonable certainty that the threshold dose for THCV and CBN would be substantially higher than the threshold for ∆9-THC, with that for ∆8-THC being unknown.

The Working Group concluded that it is very unlikely that plant-derived consumer CBD products would contain sufficient controlled phytocannabinoids (apart from ∆9-THC) to produce any pronounced psychoactive effects unless they were purposely added to the product.

A need for advanced analytical techniques

During the analyses, a set of three commercially available consumer CBD products, an oil, a spray and a body wash, was circulated to the participating laboratories and the analytical findings returned were evaluated. The laboratories that were participating in this analysis used a variety of analytical techniques and protocols. This trial established that while the majority of the laboratories were able to produce satisfactory results for the amount of CBD in the products supplied, the results for other controlled phytocannabinoids, which were present in the samples at lower concentrations, were more varied. Many laboratories were either unable to detect or to reliably quantitate some or all of the other phytocannabinoids.

That revealed the need to apply advanced analytical techniques, such as LC-MS/MS, to achieve the sensitivity necessary to accurately quantitate the controlled phytocannabinoids present in CBD products.