Following a request from European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety of hemp (Cannabis genus) for use as animal feed.
Four essentially different types of feed materials may be derived from the hemp plant: hemp seed (26 to 37.5 % lipids, 25 % crude protein, 28 % fibre), hemp seed meal/cake (about 11 % lipids, 33 % crude protein, 43 % fibre), hemp seed oil (about 56 % linoleic, 22 % alpha-linolenic acid) and whole hemp plant (including hemp hurds, fresh or dried). Further products are hemp flour (ground dried hemp leaves) and hemp protein isolate from seeds.
Hemp seed and hemp seed cake could be used as feed materials for all animal species. The maximum incorporation rates in the complete feed could be 3 % in poultry for fattening, 5–7 % in laying poultry and 2–5 % in pigs for hemp seed and hemp seed cake, 5 % in ruminants for hemp seed cake and 5 % in fish for hemp seed.
The whole hemp plant (including stalk and leaves) would be, due to its high fibre content, a suitable feed material for ruminants (and horses), and daily amounts of 0.5 to 1.5 kg whole hemp plant dry matter (DM) could likely be incorporated in the daily ration of dairy cows.
The hemp varieties allowed for cultivation in Europe must contain < 0.2 % THC (in dry matter basis). In conduct of the official control, 2151 samples were collected in Europe between 2006 and 2008 showing a mean THC content of 0.075 %, 2.6 % of the samples exceeding the maximum content (average: 0.33 % THC). In the absence of further data, the FEEDAP Panel considered data from the official control as conservative surrogates of the THC-content of the whole hemp plant-derived feed materials.
Hemp seeds have a low content of THC, mainly found on the outside of the seeds, which is mainly the result from physical contamination by the plant leaves. The maximum value found in un-treated seeds was 12 mg THC/kg.
No studies concerning tolerance or effects of graded levels of THC in food-producing animals have been found in literature. However, several case reports describing accidental poisoning are available: if poisoned animals are subjected to proper treatment, the prognosis for full recovery is excellent.
Based on a very limited number of studies performed in laboratory animals, farm animals and humans, following essentially single intravenous administration, oral or inhalation exposure to THC, it may be assumed that both the parent compound and its metabolites with psychoactive properties (especially 11-OH-THC) are distributed in the different tissues and organs, and excreted in milk. However, there is a lack of specific studies performed in food-producing species fed hemp products.
No data are available concerning the likely transfer of THC and its lipophilic metabolites to animal tissues and eggs following repeated administration. Fat can be considered as a target tissue for THC exposure. Based on two studies (with squirrel monkeys and dairy cows), the FEEDAP Panel adopted 0.15 % as the transfer rate of oral THC to milk from dairy cows.
Studies in humans, either after single or repeated exposure, identified psychotropic effects as a follow up of a single administration at the same lowest effective dose (the lowest dose tested) of 0.04 mg THC/kg bw, which is deemed by the FEEDAP Panel to be a realistic approximation of the LOEL. The FEEDAP Panel considers that a total uncertainty factor of 100 applied to the LOEL would be sufficient to take account of all sources of uncertainty.
The provisional maximum tolerable daily intake (PMTDI) would amount to 0.0004 mg/kg bw (corresponding to 0.024 mg for a 60-kg adult and 0.0048 mg for a 12-kg child).
Considering the results of a rat study with intra-peritoneal administration of THC (neuroendocrine effects at the lowest effective dose tested 0.001 mg/kg bw), the FEEDAP Panel cannot exclude the possibility that the provisional risk assessment underestimates potential adverse effects in particular for foetuses and new-borns.
The psychotropic effects of THC, the basis for establishing the PMTDI, were considered as acute pharmacological effects. Therefore, the consumer exposure calculation was based on a single high consumption records for milk (adjusted for other dairy products), derived from the EFSA Comprehensive European Food Consumption Database and expressed as P95 values of consumers only. In the exposure scenario, 2 L and 1.5 L milk equivalents were used for adults (60 kg bw) and children of one to three years old (12 kg bw), respectively.
Different exposure scenarios were considered: (i) daily intake rates per cow of 0.5, 1.0 and 1.5 kg hemp plant-derived feed material with the maximum permitted THC content of 0.20 % or the mean THC content observed in 2008 (0.08 %), (ii) three different milk yields (15, 25 and 35 L/day) assuming a constant transfer rate of THC regardless of the milk yield. In all scenarios calculated with the maximum permitted THC content, the exposure to THC was considerably above the PMTDI (4 to 25 times higher in adults, 13 to 90 times higher in children). Considering the mean THC content (0.08 %) of hemp plants grown in the EU, the consumer exposure would be reduced by a factor of 2.5 (0.2/0.08); however, the PMTDI would still be exceeded in all scenarios. By applying the same exposure calculations to hemp seed-derived feed materials containing as a worst case estimate a maximum of 0.0012 % THC, the resulting exposure of adults and children (one to three years old) was below the PMTDI in all scenarios.
Although no data is available for edible tissues, the lipophylic properties of THC would suggest that the conclusions drawn from milk consumption would in principle apply to other animal products. Consequently, the FEEDAP Panel does not see any option for the use of whole hemp plant-derived feed materials in animal nutrition. In contrast, feeding hemp seed was considered safe for the consumer.
Feed materials do not require an assessment of their environmental impact.