Tropane alkaloids are natural plant substances that occur in a variety of plants, particularly in the genus Solanum, such as for example henbane, Jimson weed (datura) and deadly nightshade. More than 200 different tropane alkaloids are known, for instance atropine and scopolamine.
Plants form tropane alkaloids as a protection against being eaten (e.g. by insects). Tropane alkaloids are also toxic to humans.
Symptoms of poisoning by these substances are in particular dryness of mucous membranes (reduced flow of saliva, dry mouth), dryness and redness of the skin, possibly dilation of the pupils, for high quantities dizziness, impaired vision, palpitations, disorientation and hallucinations. These symptoms occur relatively quickly after ingestion (5 to 30 minutes).
Should symptoms of this kind occur following consumption of food that may be contaminated, e.g.millet or buckwheat or foodstuffs made from these, please contact a doctor. Any food leftovers or packaging of ingredients used to prepare the meal should be submitted to the responsible food supervisory authority.
Cases of poisoning are known to have occurred for instance in Slovenia, where in 2003 a total of 73 consumers ate buckwheat products contaminated with Jimson weed (datura) seeds. Symptoms such as dry mouth, hot, red skin, impaired vision, tachycardia, urinary retention, ataxia, speech impairment, disorientation and hallucination were observed. Symptoms occurred within 48 hours. In approx. half of the products, levels were measured at above 3 mg/kg (3000 µg/kg), with the highest reading being 38 mg/kg (38,000 µg/kg) (Perharič et al. 2013, Perharič 2005).
In Austria in 2006, seven people showed signs of poisoning after eating a meal containing millet contaminated with Jimson weed (datura) seeds. Symptoms ranged from dryness of the mouth to dizziness and hallucinations. The symptoms subsided within 48 hours (Fretz et al. 2007).
In Germany, according to the Federal Institute for Risk Assessment (BfR) there are no known cases of health impairment to infants, young children or consumers in other age groups through consumption of tropane alkaloid-contaminated products (BfR, 2013).
What daily intake levels from foodstuffs are safe for humans?
A safe total intake of atropine and scopolamine of 1.04 µg has been calculated for a person weighing 65 kg. For a pre-school child weighing 20 kg, a safe total intake of 0.32 µg of atropine and scopolamine has been calculated.
Currently no official limit values exist for atropine and scopolamine. At European level, however, limit values are being discussed for buckwheat and millet-based food for children. The European Food Safety Authority (EFSA) has published a health-related recommended value: this acute reference dose (ARfD) is the quantity of a substance per kilogramme of bodyweight that may be ingested via food as part of a meal or on a daily basis with no detectable risk to the consumer. For atropine and scopolamine this acute reference dose is 0.016 µg per kilogramme of bodyweight. In case of impurities this acute reference dose can be exceeded by approx. 40 µg/kg of foodstuff.
Why can tropane alkaloids occur in foodstuffs?
Plants such as Jimson weed (datura) also grow in cereal fields. When the cereal crop is harvested, these plants are also harvested. In this way the seeds of plants that form tropane alkaloids can also end up in among the cereal grain. While ways of filtering out the extraneous seeds do exist, if the seeds are approximately the same size, these are not always completely effective. These extraneous seeds can then also be found in the cereal products and result in measurable levels of tropane alkaloid content.
The basic aim in farming is to avoid there being any of these extraneous plants in the field. Since prevention options in organic farming are limited, extraneous seed contamination of organically farmed cereal products is more likely to occur.
Perharič L, Koželj G, Družina B, Stanovnik L. (2013): Risk assessment of buckwheat flour contaminated by thorn-apple (Datura stramonium L.) alkaloids: a case study from Slovenia. Food Addit Contam Part A Chem Anal Control Expo Risk Assess.;30(2):321-30
Perharič, L. (2005). Mass tropane alkaloid poisoning due to buckwheat flour contamination. Clinical Toxicology, 43, 413
Fretz R, Schmid D, Brueller W, Girsch L, Pichler AM, Riediger K, Safer M, Allerberger F. Food poisoning due to Jimson weed mimicking Bacillus cereus food intoxication in Austria, 2006. Int J Infect Dis. 2007 Nov;11(6):557-8. Epub 2007 May 18.
Bewertung von Tropanalkaloiden des BfR
Bewertung von Tropanalkaloiden der EFSA