Tropane alkaloids are natural plant constituents found in a wide variety of plants, especially in nightshade plants such as henbane, datura and belladonna. More than 200 different tropane alkaloids are known such as atropine and scopolamine. Plants produce tropane alkaloids to protect themselves from predators (e.g., insects). These alkaloids are also toxic to humans.

Plants such as datura also grow in grain fields. When the grain is harvested, these plants are also harvested. In this way, seeds from plants that produce tropane alkaloids can get among the cereal grains. There are ways of sifting out foreign seeds, but if the seeds are roughly the same size, this is not always entirely successful. These foreign seeds are then found in the grain products and lead to measurable levels of tropane alkaloids. In addition, sap from datura that escapes during threshing can be transferred to the harvested crop and cause contamination. The fundamental goal in agriculture is to avoid these foreign plants in the field.

Already relatively quickly (5 to 30 minutes) after ingestion of tropane alkaloids, symptoms of poisoning may occur. Symptoms of poisoning with these substances are primarily dryness of mucous membranes (reduced salivation, dry mouth), skin dryness and redness, possible pupil dilation, and in higher quantities drowsiness, visual disturbances, palpitations, disorientation and hallucinations.

Cases of poisoning are known from Slovenia, among other countries, where a total of 73 consumers had eaten buckwheat products contaminated with datura seeds in 2003. Symptoms such as dry mouth, hot red skin, visual disturbances, tachycardia, urinary retention, ataxia, speech disorders, disorientation, and hallucinations were observed. Symptoms occurred within 48 hours. Measured levels were above 3 mg/kg (3000 µg/kg) in approximately half of the products, with the highest level being 38 mg/kg (38,000 µg/kg) (Perharič et al. 2013, Perharič 2005).

In Austria in 2006, seven people showed symptoms of poisoning after consuming a millet dish contaminated with datura seeds. Symptoms ranged from dry mouth and dizziness to hallucinations. The symptoms disappeared within 24 hours (Fretz et al. 2007). According to the Federal Institute for Risk Assessment (BfR), there are no known cases in Germany of adverse health effects in infants, young children, and consumers of other age groups due to consumption of tropane alkaloid-contaminated products (BfR, 2013).

In 2015 and 2016, the levels of various tropane alkaloids in different food samples were analyzed in some European countries. Among other things, the sum content of atropine and scopolamine was determined, especially for cereals and cereal products, herbal teas, and for some legumes and other foods. The analytical results are presented in Table 1.

The results show that especially dry herbal tea mixtures (mean 13.4 µg/kg and max 428.5 µg/kg) and, to a lesser extent, products from buckwheat, millet and maize may be contaminated with atropine and scopolamine. In addition, the proportion of samples with detectable levels in the product group of herbal teas was particularly high at over 60 percent. Although the average sum contents of the other product groups are very low at less than 1 µg/kg, there are, with the exception of legumes, oilseeds and vegetable mixtures, individual products with comparatively high contamination levels (Mulder PPJ et al. 2016).

Table 1: Analytical results for the sum contents of atropine + scopolamine in different food groups, according to Mulder PPJ et al. 2016.

Since 2016, we have analyzed a total of 311 food samples from the Austrian market for tropane alkaloids. Tropane alkaloids could be found in only 16 samples.

Table 2: Our Analysis results for the sum contents of atropine + scopolamine in different food groups (excerpt).

• If symptoms of poisoning occur after eating foods that may be contaminated, such as in cereals, millet or buckwheat and foods made from them, please seek medical attention
• Any leftover food or the package used to make the dish should be handed over to the relevant food inspectorate

Intake levels of tropane alkaloids via food and possible risks.

The European Food Safety Authority (EFSA) has published a health-related guideline value: this acute reference dose (ARfD) is the amount of a substance per kilogram of body weight that can be ingested via food with a meal or within a day without any apparent risk to consumers. For atropine and scopolamine, this acute reference dose is 0.016 µg per kilogram of body weight.

For a person weighing 65 kg, this calculates to a total safe intake of 1.04 µg of atropine and scopolamine. For a preschool child weighing 20 kg, a total safe intake of 0.32 µg of atropine and scopolamine is calculated.

In 2018, EFSA prepared a detailed risk assessment on tropane alkaloids in food (EFSA 2018). The model calculations showed that in certain "worst-case" scenarios, exceedances of the acute reference dose (ARfD) could occur, especially in infants, toddlers, and children. However, the calculations are subject to some uncertainties, mainly because the majority of the underlying analytical data of tropane alkaloids in food (95% of a total of 44,184 data) were below the limit of quantification, i.e., tropane alkaloids were present only at very low levels or not at all in these samples. The model showed that in all age groups the largest proportion of tropane alkaloids is ingested via bread and other cereal flour products.

Limits for tropane alkaloids in foods

Based on EFSA's 2018 assessment, the European Commission considers the presence of tropane alkaloids, particularly atropine and scopolamine, to be a health concern. Therefore, Regulation (EU) 2023/915 sets maximum levels for certain cereals, products derived from them, and herbal teas.