Pyrrolizidine alkaloids (PA) are plant constituents that can damage health, especially the liver, after ingestion. They are therefore undesirable in food and feed.

Worldwide, PAs have been identified in about 350 plant species. They are frequently found within the families of the Asteraceae (daisy family), Boraginaceae (borage family) and Fabaceae (legume family). In Austria, native pyrrolizidine alkaloid-forming plants are, for example, representatives of the genus Greiskraut (synonym: ragwort; Jacob's ragwort, common ragwort, grove ragwort), coltsfoot and butterbur from the family of the composite plants, viper's bugloss, borage and comfrey from the family of the borage family.

To date, more than 660 different PAs are known. The occurrence of PAs in plants varies greatly by plant variety, climatic conditions, season, and part of the plant. They can enter the food supply by co-harvesting pyrrolizidine alkaloid-containing plant parts and seeds (weeds), e.g., in spices, teas, leafy vegetables, and lettuce. Animal foods such as honey, and less commonly milk or eggs, may also contain PAs if plants containing PAs are ingested through feed (EFSA 2015). Appropriate measures to avoid contamination of food with pyrrolizidine alkaloids include care in the cultivation and harvesting of lettuces, leafy vegetables and herbs, and of food before marketing.

Animal studies showed that regular consumption of relatively small amounts of PA (chronic intake) can be carcinogenic. Regular intake of higher doses can also lead to irreversible liver damage (cirrhosis) and, in extreme cases, death. There is a risk of health hazards especially for children, pregnant women and nursing mothers. For people who regularly consume tea (herbal tea, black tea, green tea, etc.), a health risk with regard to a possible carcinogenic effect cannot be excluded (EFSA 2017).

Characteristic of poisoning are pain in the upper abdomen, abdominal dropsy, nausea and vomiting. Less frequently, jaundice and fever may occur. After a few weeks, liver enlargement and hardening is usually noticeable. Acute poisoning can be fatal. Because symptoms of poisoning may not appear until days later, the cause of the poisoning is rarely recognized.

In humans, acute cases of poisoning by pyrrolizidine alkaloids ingested in high doses have been described. For example, in 1977/1978, two infants were affected who were given a certain species of ragwort(Senecio longilobus) as an herbal tea over the period of 4 to 14 days. For a two-month-old boy, this ended fatally. A six-month-old girl was diagnosed with liver cirrhosis a few months later (BfR 2016a). Since the 1970s, poisonings have also been documented from India, Pakistan and Afghanistan. In Afghanistan, liver damage most recently occurred in 2008 in individuals who had eaten cereals contaminated with seeds containing PA for 2-6 months (BfR 2016a).

Since July 1, 2022, maximum levels for pyrrolizidine alkaloids (PA) in certain foods, such as tea, herbal tea, borage, some spices and food supplements, have applied on the basis of Regulation (EU) 2020/2040.

Herbal medicinal products may only be placed on the market in Austria if their use does not exceed a maximum daily dose of 1 µg PA (BASG 2016).

Studies on pyrrolizidine alkaloids (PA) in foodstuffs

In a study published by the European Food Safety Authority (EFSA) in 2015, pyrrolizidine alkaloid levels were analysed and evaluated in a total of 1,105 plant and animal products from six European countries (France, Germany, Greece, Italy, the Netherlands and Spain) (EFSA 2015).

In Austria, we have been focussing on PA in tea, honey and spices since 2016.

Tea

Over 90 per cent of all tea samples analysed on behalf of the EFSA contained pyrrolizidine alkaloids (EFSA 2015). The average concentration in tea infusions was 6 µg/litre. The highest concentrations were found in rooibos tea (up to 64 µg/l tea infusion). However, PA levels in tea sometimes vary greatly. It is often the case that a tested sample of one type of tea (e.g. green tea) of one brand contains no PA at all, while the same type of tea of another brand contains very high levels. In order to map the situation in teas on the Austrian market, we have focussed on 187 samples since 2016. PA was detected in 54 per cent of the tea samples. Of these, 15 samples were above the future maximum level. Compared to EU-wide analyses, teas on the Austrian market were contaminated on average with significantly lower pyrrolizidine alkaloid levels (0.8 µg/l tea infusion).

Spices and herbs

Very high levels of PA were found in certain herb and spice mixtures. Dried spices such as oregano, marjoram or lovage are particularly frequently affected. The contamination is presumably due to the co-processing of PA-forming foreign plants during harvesting. Although the quantities of such herbs/spices consumed are generally low, they can make a significant contribution to the total intake of PA (BfR 2019, 2020). In 2019, we analysed 37 herb and spice samples for PAs. PAs were detected in 58 per cent of the samples. In 6 samples, the content was above the future maximum level.

Food supplements

Food supplements containing pyrrolizidine alkaloid-forming plants sometimes contain high levels of PAs. 60 per cent of the herbal food supplements examined as part of the EFSA study contained PAs in very different concentrations (EFSA 2015). The intake of such food supplements can significantly increase the intake of PA compared to the intake via conventional food consumption and thus lead to significantly higher health risks, including acute poisoning.

Animal foods

PAs can also enter animal foods such as milk, dairy products, eggs, meat and offal via the food chain through contaminated animal feed. There are currently no indications that PA concentrations occur in animal foods that would pose a health risk to consumers. In the study published by the EFSA in 2015, PA was found in only 2 per cent of 746 samples of animal foods (milk, dairy products, eggs, meat, meat products). Eleven milk samples (6 per cent) contained PA in low concentrations (between 0.05 and 0.17 µg/l). Only two egg samples contained traces of PA (0.10-0.12 µg/kg) and no PA could be detected in other animal products.

Honey

Similar to tea, pyrrolizidine alkaloid levels also vary greatly in honey. It is often the case that one type of honey contains no PAs at all, while another type contains very high levels. Due to their smaller body size, children in particular can be exposed to harmful levels of PAs through increased consumption of honey. In order to map the situation of honey on the Austrian market, we have analysed 159 samples since 2016. PAs were detected in 62 per cent of the honey samples.

The main sources through which consumers may ingest pyrrolizidine alkaloids (PAs) are teas contaminated with PAs (herbal, black, and green teas), dietary supplements, certain spices, and honey. These foods may contain amounts of PA that, if ingested over a long period of time, pose health concerns for children and adults. However, there is no acute health risk here.

• In principle, pay attention to a varied selection of foods. This can prevent one-sided exposure to potentially harmful substances.
• Drinking water is best suited to cover the daily liquid requirement. Herbal tea and tea should only be consumed alternately with other beverages (drinking water, fruit tea, unsweetened diluted fruit juices).
• Offer children primarily drinking water and not exclusively herbal tea as a thirst quencher. Fruit teas or unsweetened diluted fruit juices can also be offered as an alternative to herbal tea and tea. Black and green teas are generally not recommended for children because of the caffeine they contain.
• Pregnant and breastfeeding women should not drink herbal teas regularly or to meet their fluid needs (including herbal nursing teas). Regular increased consumption of herbal teas should be discussed with the doctor.
• Regularly changing the type or brand/manufacturer of tea and honey can reduce long-term consumption of highly contaminated products
• Honey is generally not suitable for infants in the first year of life. As it may contain certain bacterial spores that cannot yet be fought off by the infant's intestines (infant botulism)
• Beware of dietary supplements containing PA-forming plants, such as water astragalus, borage, or comfrey. Consumption of such products is not recommended, as they could immensely increase the intake of PAs
• Beware of confusion in vegetables: when preparing lettuce, leafy vegetables, and herbs, discard plant parts that cannot be assigned to any known edible plant. Instead of dried products, use fresh, clearly identifiable herbs. Special care should be taken when picking and processing wild herbs or plants yourself

Since 2011, the German Federal Institute for Risk Assessment (BfR) has regularly published opinions on PA levels in food and associated risks (BfR 2007, 2011, 2013, 2016a, 2020).

In June 2017, the European Food Safety Authority (EFSA) published a detailed risk assessment on PAs in food.

Maximum levels for pyrrolizidine alkaloids (PAs) in certain foods are set in Regulation (EU) 2023/915:

Maximum levels refer to the lower limit of the sum of the following 21 pyrrolizidine alkaloids:

Intermedin/Lycopsamine, Intermedin-N-Oxide/Lycopsamine-N-Oxide, Senecionin/Senecivernin, Senecionin-N-Oxide/Senecivernin-N-Oxide, Seneciphyllin, Seneciphyllin-N-Oxide, Retrorsin, Retrorsine-N-Oxide, Echimidine, Echimidine-N-Oxide, Lasiocarpine, Lasiocarpine-N-Oxide, Senkirkine, Europine, Europine-N-Oxide, Heliotrine, and Heliotrine-N-Oxide, and the following additional 14Pyrrolizidine alkaloids known to coelute with one or more of the above 21 pyrrolizidine alkaloids by certain analytical methods currently in use:

Indicin, echinatin, bovin (possible coelution with lycopsamine/intermedin), indicin N-oxide, echinatin N-oxide, bovin N-oxide (possible coelution with lycopsamine N-oxide/intermedin N-oxide), integerrimine (possible coelution with senecivernin/senecionin), integerrimine N-oxide (possible coelution with senecivernin N-oxide/senecionin N-oxide), Heliosupine (possible coelution with echimidine), Heliosupine-N-oxide (possible coelution with echimidine-N-oxide), Spartioidine (possible coelution with seneciphylline), Spartioidine-N-oxide (possible coelution with seneciphylline-N-oxide), Usaramine (possible coelution with retrorsine), Usaramine-N-oxide (possible coelution with retrorsine-N-oxide).

Pyrrolizidine alkaloids that can be identified individually and separately by the analytical method used shall be quantified and included in the total.