Labinfo december 2019 Pyrrolizidine alkaloids (PA) are natural toxins, exclusively biosynthesized by a wide variety of plant species (> 6000), the great majority of them belong to the Asteraceae, Fabaceae and Boraginaceae families. PAs are typical plant secondary metabolites against herbivores and are believed to be one of the most widely spread natural toxins. They can affect wildlife, livestock and humans via food consumption. Outbreaks in farm animals can cause economic losses to farmers and diverse cases of human poisoning in Afghanistan, India, South Africa and the former USSR are documented and are related to animal grazing on toxic plants, fed with contaminated feed/forage or to bread contaminated with PA-producing plant seeds.