Pyrrolizidine alkaloids in surface and shallow ground waters
Written by Vaidotas Kisielius, Jawameer Hama, Natasa Skrbic
More than 6,000 plant species produce pyrrolizidine alkaloids (PAs) as effective defense chemicals against insects and herbivores . Besides harming animals, PAs are carcinogenic and hepatoxic to humans. Authorities in many countries of the world control PAs by establishing legal limits and monitoring plant products like grain, honey, herbal tea, spices, homeopathic medicine and other. Molecular structures of PAs make them extremely soluble in water. However, information about PA leaching from plant to water is scarce. We investigated an invasive plant in Denmark Petasites hybridus that yields high biomass leafs and proliferates very close to fresh water resources, and identified at least 9 different PAs in it.
In the summer of 2019 we monitored a fresh water stream and ground water wells proximate to the plants. The stream water contained up to 0.05 μg/L of petasites-origin PAs at dry weather conditions. This number increased to up to 0.52 μg/L shortly after precipitation. Shallow ground water wells (approx. 2 m depth) contained up to 0.23 μg/L of petasites-origin PAs, whereas the deep ground water (approx 60 m.) contained no PAs. The water investigated in this particular study, except the deep ground water, is not utilized for drinking. Nevertheless, the analyses illustrate direct risk for humans and animals consuming water from sources adjacent to plants that produce PAs.
Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (UK) and Federal Institute for Risk Assessment (Germany) propose tolerable levels of 7 ng of PAs per kg BW per day . A daily consumption of more than 2 liters of the reported shallow ground water would exceed the limits for an average person. The study continues investigating additional water wells and locations in Denmark. It promotes understanding of the risk factors contributing to leaching of phytotoxins and opens the door for the future perspectives of protecting public health by developing feasible monitoring and toxin removal techniques.
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- Public statement on the use of herbal medicinal products 4 containing toxic, unsaturated pyrrolizidine alkaloids (PAs). European Medicines Agency, EMA/HMPC/893108/2011