Assertion: comfrey | /r/HasProperty | s. officinaleroot extract
Facets:
Source sentences:
text: In a 2006 short-term study using oral preparations of comfrey (S. officinale) root extract in mice and rats, no hepatic and biliary toxic effects were observed at the conclusion of the study; however, researchers did recommend that longer studies are needed to determine the safety of PA-containing plant extracts (Seremet et al., 2006).