Within limits

1 October 2020

Hemp foods, which contain different components of the hemp plant in their original or processed form, are enjoying increasing popularity worldwide. However, there’s some worry among the general public about safe levels of THC in these products. Ingredients Insight presents an article by the European Industrial Hemp Association (Eiha), which has published a study to address these concerns.

In North America, China and Europe, hundreds of hemp products are on the market and – with their valuable fatty acids and proteins – belong to the trending products of healthy nutrition.

Since small amounts of the psychoactive tetrahydrocannabinol (THC) remain in food after careful processing, limits or guideline values must be defined so the consumers are protected from side effects. As presented in a study by European Industrial Hemp Association (Ehia), a number of countries, such as Australia, Canada and Switzerland, have set themselves similar limits or guideline values. These allow producers sufficient leeway to supply consumers with a variety of hemp products, while avoiding any side effects from THC. More than 10 years of experience in Canada confirms this.

The legal situation in Europe is more complicated, however, and presents an obstacle to the further development of the industry. In Europe, there are no uniform limits or guideline values for residual THC contents in food, not even a uniform guideline for consumption. Back in 1997, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) (formerly BgVV) established THC guideline values that, until today, represent the strictest international values and have been criticised by experts for years as being too restrictive. When the Federal Ministry of Food and Agriculture (Bundesministerium für Ernährung und Landwirtschaft, BMEL) commissioned BfR to clarify some fundamental aspects regarding the assessment of the THC content in food – at the request of the monitoring authority of a federal state – many scientists and producers hoped for a comprehensive reassessment and adaptation, as well as international harmonisation of the guideline values.

These hopes were severely disappointed by BfR’s opinion, No. 034/2018, from 8 November 2018: “Tetrahydrocannabinol levels are too high in many hemp-containing foods – health impairments are possible.” Instead of a comprehensive reassessment, the 40 pages explain why the 1997 established THC guideline values would continue to apply and that, if they were to be amended, they would more likely be tightened. Germany would, therefore, create clear barriers to the growing hemp industry and make it more difficult for the population to access hemp products as a result of higher prices. In this situation Eiha, the industry association of the European hemp industry, asked the independent nova-institute to analyse and evaluate BfR’s statement. In cooperation with representatives from the scientific advisory board and the executive committee of the association, a 29-page long evaluation was created.

In the opinion of the scientists, BfR has taken the easy way out with its statement and defence of its recommendations from 1997. Much has happened since 1997; new scientific findings have been gained and comprehensive experiences with hemp foods have been made in many countries – though both have not been adequately considered. Six important scientific studies published after the year 2000 and the detailed Eiha position paper ‘Reasonable guidance values for THC (tetrahydrocannabinol) in food products’ published in September 2017, were not regarded when reviewing their own risk assessment; they were simply ignored, even though they were known to BfR. If the new scientific findings were to be considered, a defence of the old guideline values would fall short. It becomes apparent that a comprehensive revision of the recommendations is necessary, and that the THC guideline values can be significantly increased without any risk when consuming hemp products and be internationally harmonised.

In order to establish guideline values with a sufficient safety distance to undesirable effects, one must know the lowest-observed-adverse-effect level (Loael) or the no-observed-adverse-effect level (Noael) and then apply a factor that takes into account the different sensitivities of the consumers. The European Food Safety Authority (Efsa) has issued clear recommendations on the methodological approach.

The uncertainty factor

BfR applies an uncertainty factor of 20–40 to THC, since no Noael is known for THC. Therefore, in addition to the usual Efsa uncertainty factor of 10, BfR uses a further uncertainty factor of 20–40 for inter-individual differences, namely for the extrapolation from the known Loael of THC to Noael. But according to current scientific knowledge, this is no longer tenable. Due to the more recent clinical experience on active THC, it is now known where the Noael lies for the large majority of patients. An additional factor of 20–40 is, therefore, no longer justifiable.

Also, the reasoning that there is no sufficient data available on the effects of THC appears to be unreliable because in the current evaluation of THC, twice as many studies are used in the evaluation of nicotine. In addition, numerous other studies currently exist that further support a more differentiated evaluation of THC. If one compares the uncertainty factor of 20–40 with the uncertainty factors BfR assigns to other psychologically active substances, the procedure and justification no longer appears scientifically comprehensible.

For nicotine, opium alkaloids, and caffeine and alcohol especially, very low – or no – uncertainty factors are applied – even lower than the recommended standard uncertainty factor of 10 for inter-individual differences. For THC, on the other hand, a strict methodology is followed and then further exacerbated by applying an extra factor on top, which is not scientifically tenable. If, for example, BfR were to apply comparable standards to alcohol as it does to THC, bread or orange juice would no longer be marketable. Similarly, there would be no more poppyseed cakes or poppy-seed rolls if opium alkaloids were subject to the same procedure as THC.

BfR’s risk assessments for the substances are inconsistent, inscrutable and hardly comprehensible. This systematic unequal treatment of substances with similar effects will not withstand an overarching risk assessment and is scientifically outdated.

Active THC and patients

There are further errors and inconsistencies in BfR’s statement that systematically overestimate THC risks. The studies used by BfR only use active THC; whereas, in reality, THC always occurs together with other cannabinoids that can influence the effect of active THC. In addition, all studies used were medical studies and were, therefore, conducted exclusively on patients – who are usually more sensitive than healthy people. But when assessing ‘health claims’ on food, the EU Commission usually only considers studies that were carried out on healthy volunteers. Clinical studies on sick volunteers generally have the disadvantage that possibly relevant physiological parameters of the volunteers are altered. This scientific principle must of course be observed, not only in health-related effects, but also in risk assessments.

The biggest error, however, results from the imprecise distinction between total THC and the active form of THC (Δ9-THC). In most hemp foods, THC is primarily present in its non-active form (up to 90%), which only converts into its active form after prolonged heating. A complete transformation is almost impossible under normal production and preparation conditions of food.

If the guideline values refer to total THC and not only to the active form, the guideline values are systematically set too strict. In other words, BfR derives too much high-active THC contents in food in its approach. This leads to objectively inaccurate results and scientifically wrong conclusions for the risk evaluation of THC.

The bottom line

BfR has once again missed the opportunity to comprehensively revise the THC guideline values, to take account of current scientific findings and harmonise the German THC guideline values internationally. The attempt to defend the old recommendations fails because the arguments are based on outdated information, and systematically ignores studies and findings from the past 18 years for a differentiated risk assessment. The lack of a clear distinction between total THC and active THC, which has long been the scientific standard, is also a weak point of BfR’s statement that cannot be ignored.

Why BfR shows such scientifically unjustifiable severity with the THC in food – while the reference values for comparable substances such as alcohol, caffeine, nicotine and opium alkaloids are disproportionately indulgent, and generous – can at this point only be speculated. Are there lobby interests behind this? Shall competition for established products on the market be prevented? Or is it still a remnant of the fight against the alleged ‘devil drug, cannabis’? Whatever the reason, there can be no speculation about the following conclusion: the measurements and methodologies of BfR are so different that they cannot prevail. The current risk assessment of THC by BfR is inadequate, and according to current scientific knowledge, it goes against international experiences and potential harmonisation, and should be revised.

The author’s views are their own and do not necessarily represent those of Ingredients Insight.


The uncertainty factor BfR applies to THC. German Federal Institute for Risk Assessment


Adverse effects


Effects on the central nervous system: euphoria, clouding of consciousness, impairment of cognitive abilities and judgement, reduced driving ability and ability to operate machines, aggressiveness, nausea,vomiting, habituation, addiction and withdrawal symptoms (irritability and dysphoria).


Effects on the central nervous system: restlessness, irritability, nervousness, tremors, insomnia, anxiety, habituation, dependence, addiction and withdrawal symptoms (irritability and dysphoria). Effects on the vegetative nervous system: increase of heart rate, arrhythmias, vasoconstrictor in the brain, and vasodilator in the periphery.


Effects on the central nervous system: dizziness, habituation, dependence, addiction, and withdrawal symptoms (irritability and dysphoria).
Effects on the vegetative nervous system: stimulating, increase in salivary flow, increase in heart rate and blood pressure, and narrowing of peripheral blood vessels.

Opium alkaloids(morphine andcodeine)

Effects on the central nervous system: nausea, vomiting, loss of appetite, constipation, sedation, drowsiness, mood changes, euphoria, miosis, respiratory depression, constipation, and changes in the hormonal and autonomic nervous systems.


Effects on the central nervous system: mood swings, fatigue, dizziness, loss of consciousness, insomnia, nausea, euphoria, anxiety, habituation, dependence, addiction, and withdrawal symptoms (irritability and dysphoria).
Effects on the vegetative nervous system: increased heart rate, and changes in blood pressure.

Source: European Industrial Hemp Association

Compared with nicotine, opium alkaloids, and caffeine and alcohol, THC has very high uncertainty factors applied that are not scientifically tenable.
Limits must be defined in order to protect consumers, as small amounts of THC remain in food after processing.

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