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PEER-REVIEWED PAPERS
Current Status of THC
in German Hemp Food Products
Dirk W. Lachenmeier
Stephan G. Walch
ABSTRACT. In 1996, the prohibition of the cultivation of non-drug
Cannabis sativa L. (hemp) with minor content of the psychoactive
∆9-tetrahydrocannabinol (THC) was lifted in Germany. Nowadays, a
wide variety of hemp food products is offered on the market. As help for
evaluation of such products, this article provides information on all as-
pects of hemp as foodstuff. An introduction to the current law situation
in Germany and the European Union is presented. In particular, sugges-
tions for the food regulatory and food chemical evaluation of hemp food
products are made.
Between 1998 and 2003, a significant linear decrease in the THC con-
centrations for the product groups hemp tea (N = 19, R = ⫺0.73, p <
0.0001) and hemp oil (N = 60, R = ⫺0.23, p = 0.05) was observed. The
prescribed use of certified hemp seed by the EU and the increase of con-
trols on manufacturers have obviously led to a significant decline of
THC concentrations in hemp food products. The maximum THC con-
Dirk W. Lachenmeier and Stephan G. Walch are affiliated with Chemisches und
Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weißenburger Str. 3, D-76187 Karlsruhe,
Germany (Web-site: www.cvua-karlsruhe.de) (E-mail: Lachenmeier@web.de).
Journal of Industrial Hemp, Vol. 10(2) 2005
Available online at http://www.haworthpress.com/web/JIH
©2005 by The Haworth Press, Inc. All rights reserved.
doi:10.1300/J237v10n02_02 5
This electronic prepublication version may contain typographical errors and may be miss-
ing artwork such as charts, photographs, etc. Pagination in later versions may differ from
this copy; citation references to this material may be incorrect when this prepublication
edition is replaced at a later date with the finalized version.
tent in current purchasable hemp food products is ten to a hundred-fold
lower than those found in the studies of the 1990’s. These levels of THC
in hemp food do not cause regulatory or health concern anymore. How-
ever, ongoing quality control is needed to maintain low THC levels. This
includes both the use of low THC varieties and proper seed cleaning.
[Article copies available for a fee from The Haworth Document Delivery Ser-
vice: 1-800-HAWORTH. E-mail address: <docdelivery@haworthpress.com>
Website: <http://www.HaworthPress.com> ©2005 by The Haworth Press, Inc.
All rights reserved.]
KEYWORDS. Hemp food, hemp, Cannabis sativa L., cannabinoids,
tetrahydrocannabinol (THC), food regulation
INTRODUCTION
In 1996, after a long-time of prohibition in Germany, the law for nar-
cotics (BtMÄndV, 1996) was changed and since then the cultivation of
non-drug Cannabis (hemp) has been legal. As a consequence, hemp
containing food products are experiencing a revival. Since the mid
1990s, hemp food has gradually expanded into the natural product mar-
ket and it is increasingly found in natural food stores for its positive nu-
tritional and health benefits. The first hemp food product to reach the
market was hemp oil in 1995 (Karus, 1995). Nowadays various hemp
food products are available, for example hemp leaves (tea), hemp seeds,
hemp oil, flour, beverages (beer, lemonade), and cosmetic products. In
the meantime a flourishing trade is establishing itself via the internet.
In this article the development since 1996 concerning the psychoac-
tive cannabinoid ∆9-tetrahydrocannabinol (THC) in hemp food prod-
ucts is described, and guidelines to assist food control are given.
HEMP AS FOOD
The hemp plant is primarily a fiber supplier. As by-product the fruits,
small round nuts (usually called hemp seeds), are harvested and are sold
traditionally as bird or fish feed. Because of their fat content of 30-35%
they can also be used for the extraction of oil. It produces a green, me-
dium strong drying oil whose glycerides consist of 40-60% linolic acid
and 14-28% linolenic acid (Franke, 1997). The protein of the hemp seed
contains all 8 essential amino acids and they are in the necessary propor-
6 JOURNAL OF INDUSTRIAL HEMP
tions for human nutrition (Johnson, 1999; Mölleken, 1999). Hemp oil
contains the highest proportion of unsaturated fatty acids of all vegetable
oils, and contains nutritionally valuable essential fatty acids (approx.
75%) (Leizer et al., 2000; Mölleken, 1999). Therefore, the most promis-
ing product of Cannabis cultivation is the seed and its derived products
for utilization as food (Johnson, 1999).
A problem is that the unsaturated fatty acid molecules are susceptible
to oxidation, especially when they are exposed to light or heat (Mediavilla
et al., 1997). Therefore, hemp oil has a short shelf life in comparison to
other cold-pressed oils, such as olive oil. This disadvantage makes the
commercial exploitation of hemp oil difficult (Johnson, 1999; Matthäus
et al., 2001). In addition, hemp oils are avoided by many consumers be-
cause of the unfamiliar taste and smell (Mediavilla et al., 1997).
The application of hemp as food is currently restricted, because avail-
able hemp species have been bred to target a high fiber production and
not a high seed yield (de Meijer, 1995). The oil content of the fruits var-
ies between 9 and 34%. The most important breeding goal is, therefore,
to obtain ripe seeds under Central European conditions (El-Ghany,
2002). There is still some breeding potential, especially in regard to an
increase of the gamma-linolenic acid content, as well to increase the
tocopherol content for anti-oxidation protection of the oil (Matthäus et
al., 2001).
THC PROBLEM
Generally all parts of the Cannabis plant can contain cannabinoids.
The low but detectable concentration in the seeds, which do not contain
glandular trichomes, may be explained by diffusion of THC from other
parts of the plant before harvest. Higher concentrations may result from
further contamination during harvest. Therefore the cleanliness of the
seeds plays the most decisive part in the concentration of THC in the
seeds. The largest proportion of THC can be found on the surface of the
seed coat. As a consequence only very low THC concentrations are
found inside the seed (less than 2 mg/kg with drug Cannabis and less
than 0.5 mg/kg with non-drug Cannabis) (Ross et al., 2000).
For its application as a food product it is important that the THC con-
tent of the seeds is not increased by impurities from THC-rich plant
parts, nor by corresponding cultivation conditions (BgVV, 1997).
Because of the drug problem, the breeding of plants with low THC-
content was started in France and in the former Soviet-Union in the
Dirk W. Lachenmeier and Stephan G. Walch 7
1970s, followed by Hungary at the beginning of the 1980s (El-Ghany,
2002). Present day non-drug Cannabis species follow the guidelines of
the European Union (EU), which demand a THC-content of less than
0.2%. The selection of phenotypes with fewer than 0.05% THC has
been successful (El-Ghany, 2002; Mechtler et al., 2004). Psychoactive
effects from the consumption of non-drug Cannabis plant parts have not
been observable (Grotenhermen and Karus, 1998).
FOOD LEGISLATION
The THC limit for hemp (measured in the upper third of the plant) has
been gradually lowered from 0.5% (1984) to 0.2% (since 2002) (Coun-
cil of the European Communities, 1998). In Switzerland all plant variet-
ies of Cannabis can be grown legally, and some with high THC content
are usual. However THC content limitations were applied for hemp as
food (Mediavilla et al., 1997). After decontrol of hemp cultivation in
1996 (BtMÄndV, 1996) in Germany, the former federal institute for
health protection of consumers and veterinary medicine (BgVV, today:
Federal institute for risk assessment, BfR) estimated that the acceptable
daily intake should only be 1-2 µg/kg/day (BgVV, 1997). From these
estimations the following THC limits for food were derived in the year
2000: beverages (alcoholic and non-alcoholic): 5 µg/kg; edible oil:
5000 µg/kg; and other food: 150 µg/kg (BgVV, 2000).
Hemp cultivation for fiber production is subsidized in the European
Union and the THC content is controlled annually. Therefore, it is guar-
antied that only seed from varieties with a low THC content, according
to the maximum limit are used. It has turned out through the new, inten-
sified regulations, that the risk of cultivation of high-content THC spe-
cies is reduced to a minimum (Council of the European Union, 2000).
FOOD CHEMICAL ASPECTS
THC-Content of Hemp Food Products
Hemp food products, even those made from non-drug Cannabis,
commonly contain analyzable THC amounts (Table 1). Earlier analyses
of hemp oil revealed a wide range of concentrations, between 11.5-117.5
mg/kg (Bosy and Cole, 2000) and 7-150 mg/kg (Alt, 1997). The highest
concentrations found in oil were reported by a Swiss working group.
8 JOURNAL OF INDUSTRIAL HEMP
They obviously included products made from drug hemp in their analy-
ses: 4.1-880 mg/kg (Zoller et al., 2000), 3-1500 mg/kg (Lehmann et al.,
1997), and even 2-3568 mg/kg (Mediavilla et al., 1997). In hemp tea,
THC contents of 1020-1480 mg/kg (Zoller et al., 2000) and 5000 mg/kg
(Giroud et al., 1997) were discovered in the leaves, and between 1.0
mg/kg (Zoller et al., 2000) and 2.4 mg/kg (Giroud et al., 1997) in the re-
spective tea infusions. Low THC concentrations were only found in
beverages, such as beer (0.004-0.016 mg/l (Iten and Coray, 1996)) and
liqueur (0.02 mg/l (Alt and Reinhardt, 1997)), as well as in seed (0-12
mg/kg (Ross et al., 2000), 3.9-5.2 mg/kg (Zoller et al., 2000)). Apart
from the studies of the years 1996-2000, no current data about the THC
Dirk W. Lachenmeier and Stephan G. Walch 9
TABLE 1. THC content of selected hemp food products. Results from various
studies and own analyses (nd: not detected).
Hemp product Studies 1997-2000 (THC mg/kg) Studies 2004-2005 (THC mg/kg)
Oil 7-150 (Alt, 1997)
3-1500 (Lehmann et al., 1997)
2-3568 (Mediavilla et al., 1997)
4.1-880 (Zoller et al., 2000)
11.5-117.5 (Bosy and Cole, 2000)
1.36-12.4 (Lachenmeier et al., 2004)
2-3.3 (CVUA Karlsruhe)
0.025 (Pellegrini et al., 2005)
Tea (Leaves) 1020-1480 (Zoller et al., 2000)
5000 (Giroud et al., 1997)
4.37-15.53 (Lachenmeier et al.,
2004)
3.3-92.7 (CVUA Karlsruhe)
Tea (Infusion) 1.0 (Zoller et al., 2000)
2.4 (Giroud et al., 1997)
0.04-0.23 (Lachenmeier et al., 2004)
0.006-0.039 (CVUA Karlsruhe)
Beer 0.004-0.016 (Iten and Coray, 1996) nd (Lachenmeier et al., 2004)
nd (CVUA Karlsruhe)
0.005 (Pellegrini et al., 2005)
Liqueur 0.02 (Alt and Reinhardt, 1997) nd (CVUA Karlsruhe)
0.008 (Pellegrini et al., 2005)
Seeds 0-12 (Ross et al., 2000)
3.9-5.2 (Zoller et al., 2000)
0.29-3.36 (Lachenmeier et al., 2004)
0.28-2.6 (CVUA Karlsruhe)
0.328 (Pellegrini et al., 2005)
content of hemp food products are available. The CVUA Karlsruhe,
part of the German official food control system, analyzed the THC con-
tent of 19 hemp food products in 2004. In 15 products (79%) THC was
detected, while in the remaining 4 samples no THC was found. In com-
parison to earlier studies, the THC contents determined in recent years
were considerably lower. The reduced limit required for THC in seeds
seems to have the desired effect on hemp food products.
The results of the CVUA Karlsruhe are confirmed by a recent publi-
cation in which 30 hemp food products were examined (Lachenmeier et
al., 2004). Infringement of the THC limit was described only in isolated
cases. The THC content of hemp tea ranged from 4.37 to 15.53 mg/kg in
the Cannabis leaves and from 0.04 to 0.23 mg/kg in the tea infusion, ex-
ceeding the upper limit of the German guidance value for beverages.
High contents of THC, beyond the guidance value of 0.15 mg/kg for
other foods, were determined in seeds and flour (0.29-1.07 mg/kg), cold
cuts (0.20 mg/kg) and Cannabis pastilles (0.16 mg/kg). One oil sample
with 11.48 mg/kg also exceeded the guidance value for edible oils of 5
mg/kg. However, the majority of the analyzed samples revealed that
THC concentrations were below the guidance values; in the range
0.01-4.44 mg/kg. In two beverage samples (a soft drink and beer) THC
could not be detected, whereas in all samples cannabidiol (CBD) and
cannabinol (CBN) were present.
Our results were verified by another recent publication. Pellegrini et.
al (2005) analyzed six hemp food products from the Italian market find-
ing relatively low THC contents.
The prescribed use of certificated hemp seed by the EU and the in-
crease of controls on manufacturers have obviously led to a significant
decline of THC concentrations in hemp food products. In the USA it has
also been reported that, through a more careful cleaning of the seed,
since 1998, a significant decline in THC concentrations was achieved
(Leson et al., 2001). The maximum THC content in current purchasable
hemp food products (Lachenmeier et al., 2004) is ten to a hundred-fold
lower than those found in the studies of the 1990’s (Alt, 1997; Bosy and
Cole, 2000; Giroud et al., 1997; Lehmann et al., 1997; Mediavilla et al.,
1997; Zoller et al., 2000). In respect of the sample results of the CVUA
Karlsruhe between 1998 and 2003, and taking into account the values
described in the literature, a significant decrease in the THC concentra-
tions of hemp tea (N = 19, R = ⫺0.73, p < 0.0001) and hemp oil (N = 60,
R=⫺0.23, p = 0.05) was observed using linear regression. On the other
hand, in the case of seeds (N = 27, R = ⫺0.29, p = 0.13) and beverages
10 JOURNAL OF INDUSTRIAL HEMP
(N = 34, R = ⫺0.21, p = 0.22) no decrease in respect of the 5% level of
significance has been provable.
Origin of the Hemp Used for Food Product Manufacturing
Recently it was described that the simultaneous determination of
THC, CBD and CBN in hemp containing food products and a calcula-
tion of the Cannabis-phenotype-ratio ((THC + CBN)/CBD), allows dis-
crimination between non-drug and drug Cannabis as food ingredients
(Lachenmeier et al., 2004). In the majority of investigated samples, in-
cluding all products labeled as originating in the EU, CBD was the
analyte showing the highest concentration, and therefore the pheno-
type-ratio was below 1. In the evaluation of these products, it can be as-
sumed that they were derived from non-drug Cannabis in accordance to
the law. In Figure 1, the discrimination is visualized using principal
component analysis (PCA). The first component (PC1) divides the food
products into non-drug or drug Cannabis. Component 2 (PC2) depends
on the concentration of cannabinoids.
Only six of the examined products were derived from drug Cannabis.
It was noticed, that the origin of these products was partly Switzerland.
Due to the liberal legal situation, which allows the cultivation of all
Dirk W. Lachenmeier and Stephan G. Walch 11
Food derived from
non-drug
Cannabis
Food derived from
drug
Cannabis
PC2
PC1
⫺10123456
3
2
1
0
1⫺
FIGURE 1. Multivariate data analysis (PCA) for the visualization of 36 hemp
food products as given by Lachenmeier et al. (2004).
kinds of hemp, the use of drug-type Cannabis for food production can
be assumed. As a consequence, it is advisable that official food control
should determine the content of CBD and CBN simultaneously with the
THC content, because the phenotype-ratio can confirm the labeling of
origin of hemp food products. Of course, there are no health conse-
quences of hemp food derived from drug Cannabis if the THC content
is below the concentrations recommended by the BgVV. From the
viewpoint of consumer protection, no objection can then be made
against the import of such products of countries outside the EU that
have more liberal laws.
FOOD REGULATORY ASPECTS
The lowest oral administered dose of THC, which after repetitive ad-
ministration causes psychoactive effects in adults, is 2.5 mg/day. This is
equal to the administration of approximately 40 µg/kg of bodyweight per
day, if a bodyweight of 60 kg is assumed. Food products leading to the
uptake of such higher doses, if consumed daily, have to be considered a
threat to the consumer health and should therefore be controlled. To elim-
inate uncertainties, such as a variation in individual sensitivity, kinetic
specialties (redistribution, long half-life), interaction with other hemp or
food ingredients or certain drugs, the BgVV advises that a daily uptake of
1-2 µg/kg bodyweight should not be exceeded. This uptake limit is
20-40-fold lower than the lowest known effective dose (BgVV, 1997).
Marginal violations of the limit can usually be tolerated. Samples, which
exceed the limit twice, have to be considered to be deteriorated. Hemp
food products which greatly exceed the limit, and therefore contain
amounts of THC that are close to the lowest known effective dose have to
be judged as unfit for consumption. The CVUA Karlsruhe suggests that
the labeling of products as “THC free” should be considered as deceiving
the consumer, because a significant concentration of THC can be found
in every product. Products with low hemp content, but with a special
stress on the nutritional value of hemp, should be rated likewise.
RATING OF SPECIAL FOOD PRODUCTS
Hemp Beer
In work by Hupf et al. (1997) the organoleptical value, and therefore
the character of dried hemp inflorescence, watery infusions and beer ex-
12 JOURNAL OF INDUSTRIAL HEMP
tracts (called hemp beer) as food products were examined. After the
organoleptical tests, the authors came to the conclusion that none of the
products provided a significant consumption value. Official food con-
trol first classified hemp inflorescences as additives (BgVV, 1997) (e.g.
taste enhancing substance), but this opinion was not affirmed because it
was determined that they have prevailing attributes as food. Such prod-
ucts also do not fall into the requirements of regulation No 258/97 (EC)
regarding novel food products and ingredients (Taschan, 1999). Eul
(1997) pointed out that the ingredient “hemp” for beer distributed in
Germany does not comply with the German beer purity law. At present
only a few Swiss made products are available under the designation
“hemp beer”. The THC problem is of minor importance in this group of
products, because the lipophilic THC is extracted by the watery wort in
small amounts. In 1996, Swiss made hemp beer was analyzed by Iten
and Coray (1996) and only a marginal THC content between 3 and 16
µg/l was detected. In recent study (Lachenmeier et al., 2004), and in
experiments of the CVUA Karlsruhe, no THC could be detected in
hemp beer.
Hemp Seeds
A high concentration of THC in the seeds and the flour made from
them, can be caused either by an insufficient harvest technology that
leads to contamination of the seed with THC rich leaves (Ross et al.,
2000), or by inadequate cleaning and handling (Mediavilla et al., 1997).
The THC content of hemp oil is also caused by the concomitant extrac-
tion of leaves and resin, which stick to the seeds during oil production.
The THC content in oil products and seed has therefore to be under-
stood as a contamination that exists in many available products (Bosy
and Cole, 2000). Samples that exceed THC concentrations have to be
officially rejected because they are produced contrary to European law.
According to Council Regulation (EEC) No 315/93 laying down Com-
munity procedures for contaminants in food (Council of the European
Communities, 1993), no food containing a contaminant in an amount
unacceptable from the public health viewpoint, and in particular at a
toxicological level, should be placed on the market. Furthermore, con-
taminant levels should be kept as low as can be reasonably achieved
through following good practices. In our opinion, an offence against
good practices can be assumed if the BgVV limits are exceeded by more
than twice. Considering lot-to-lot differences and inhomogeneities in
the sampling process, manufacturers were advised of their duty to
Dirk W. Lachenmeier and Stephan G. Walch 13
exercise diligence and to use state-of-the-art measures needed to limit
the content of THC.
Hemp Tea
Hemp teas, the leaves of the hemp plant, have regularly shown to ex-
ceed THC limits. In contrast to the seed, the THC concentrations found
in hemp tea cannot be judged as contamination. In this case the cause is
the glandular trichomes of the leaves. A rejection of these products on
the basis of Council Regulation No 315/93 (Council of the European
Communities, 1993) is therefore impossible. A further problem is that it
is as yet uncertain whether the limits apply to the tea leaves or to the
infusion. An evaluation of the end product is the current practice. Tea
infusions are therefore made according to the instructions of the manu-
facturers, then analyzed and evaluated on the basis of 5 µg/kg as a limit.
If the limit is significantly exceeded, an objection against the product is
registered. The manufacturers are also informed of those cases where
tea products exceeded the limit, but not in such a way that they could be
declared as unfit for sale. Inhomogeneous tea samples lead to a big vari-
ation in analyzed THC concentrations. The manufacturers have been in-
formed of their obligation for diligence regarding their products, and
self-control measures were recommended if single batches exceeded
the limit. It should also be documented whether the THC content is a re-
sult of seasonal and annual fluctuations (e.g. different vegetation condi-
tions). Controls at the production level need to be put in place to test the
plants prior to production. It was further recommended that the conse-
quences for the recipe be documented, and that the amount of tea leaves
in each sale unit be controlled.
CONCLUSION
The critical product groups that should be intensively scrutinized by
official food control in the future are hemp seeds and their derived prod-
ucts (such as hemp flour, hemp oil). The seed, which is actually THC
free, is contaminated by THC rich leaves through inadequate harvest
technologies. In hemp oil an enrichment of the lipophilic cannabinoids
can be observed, especially if cleaning procedures are inadequate be-
fore oil production. If, in the case of seed products, an infringement of
the limit is detected, the manufacturer should be made aware of the
availability of state-of-the-art harvest and production technology, and
14 JOURNAL OF INDUSTRIAL HEMP
reminded of his obligation to take reasonable care with his products. In
fact, the product itself should not be the subject of rigorous testing but
the method of production. This may lead, if adopted as a strategy, to
hemp seed products being deregulated completely.
On the other hand, the case for hemp teas is more complex. Such
products require greater scrutiny because they are made of hemp leaves
which are rich in the glandular trichomes, in which the cannabinoids are
accumulated. Next to the covering leaves of the inflorescence they con-
tain the highest concentration of cannabinoids. The goal should be to
work towards Europe-wide regulations for hemp food products which
could replace national guidelines.
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RECEIVED: 17 November 2004
ACCEPTED IN REVISED FORM: 25 March 2005
Dirk W. Lachenmeier and Stephan G. Walch 17
