While many plant species enjoy great popularity for ornamental aspects, medical properties or other valuable features, however, respective health risks often are not considered as cautiously or known at all yet.
Plants conquered emerged land earlier than any other living organism and have been subject to a vast amount of predators throughout their evolutionary history as being rather low-rated on the food chain. Therefore it is not really a surprise the strongest organic toxins worldwide are produced by plants.
As an interested, thoughtful and prudent enthusiast it surely belongs to my duty to communicate potential health risks arising from non-attentive cultivation of this plant family as well.
Aristolochia species contain a wide variety of bitterns, odorants, alkaloids, etc. (as most plants do) but one particular component has been object of investigations in various contexts: Aristolochic acids (AA).
This chemical is considered the most important concerning the former reputation for its medical properties (childbirth, diarrhea, gastrointestinal disorders, respiratory problems, arthritis, edema, even snakebites and many more) - so many important features the generic name Aristolochia can be translated to "the best for childbirth".
Although most of these positive aspects could indeed be verified one big contrarious factor needs to be taken into account: AA proved to be a potent mutagen and carcinogen, being especially toxic to liver and kidneys which is the rightly reason for all medicines and treatments containing AA to be banned in western countries.
The highest AA amounts (up to 1 %) seem to be found in the roots, whereas seeds (~ 0,5%) and leaves (< 0,1%) contain lower doses.
Although AA is an organic macromolecule, badly soluble in water and one could argue the uptake via skin is almost impossible concerning its chemical properties, AA still is not sufficiently investigated yet and the safety under cultivation conditions depends on your own cautiousness of course.