It is often claimed that ragwort poses a risk to human health. This is not the case. Ragwort does on rare occasions cause the death of animals but it poses no serious risk to humans.
To understand this you must first understand how and why ragwort can poison animals.
Ragwort contains chemicals called Pyrolizidine Alkaloids. These are actually not poisonous but become poisonous inside the animal. The first stage occurs in the gut where the digestive process degrades the alkaloids. Then in the liver they are further broken down into compounds which can attach themselves onto DNA in the nuclei of cells. It is important also to realise that these components can attach themselves to other compounds in the cell. where they have no serious toxic effect. Small doses may be therefore have no effect at all.
The claim is often made that Ragwort is toxic to humans because the alkaloids can be absorbed through the skin, but research shows that they are poorly absorbed and as is shown above the first stage in the alkaloids becoming toxic takes place in the gut. The small amounts that can be absorbed through the skin are not converted to a toxic form and are quickly excreted.
Another claim raised is that meat from animals that have eaten ragwort is poisonous. This is not true ether. It is commonly believed that the alkaloids accumulate in the plants. A knowledge of mammalian biochemistry shows that these are not the kinds of chemicals that do this. (Even though the science is clear it did not prevent the Scottish Government repeating this myth in a consultation document. A strong indication of official scientific ignorance and carelessness over this issue.)
The simple fact is that any alkaloids not converted are quickly excreted and do no accumulate in meat any which are converted into a toxic form are inactivated by combination with DNA or other substances in the cell and become non-toxic. Therefore there is no risk from the meat.
Some individuals are sensitive to the handling of ragwort because in common with many members of the daisy family they are sensitive to another set of chemicals called sesquiterpine lactones. And can suffer an allergic reaction in the skin. However these chemicals do not cause liver toxicity.