Assertion: comfrey's use | /r/CapableOf | become controversial
Facets:
value: quite
type: DEGREE
value: due to scientific studies
type: CAUSE
Source sentences:
text: While comfrey is an herb with a long history of many different uses, its internal use has become quite controversial due to scientific studies, some dating back 40-60 years, that revealed potentially harmful effects of pyrrolizidine alkaloids (PAs) (Moreira et al., 2018), which are found in comfrey.