Assertion: comfrey's alkaloid | /r/HasProperty | substance
Facets:
Source sentences:
text: Comfrey contains pyrrolizidine alkaloids, substances that can cause liver damage, cancer, and even death, so it should be never be taken by mouth.
text: Comfrey has been shown to contain pyrrolizidine alkaloids (PAs), which are substances that we know are potentially toxic to humans by causing liver damage.