Assertion: comfrey's pyrrolizidine alkaloid | /r/HasProperty | limited to 4 to 6 weeks per year
Facets:
Source sentences:
text: AHPA reports that in Germany, the recommended external application of comfrey is a daily exposure at or below 100 μg unsaturated pyrrolizidine alkaloids limited to 4 to 6 weeks per year (Gardner & McGuffin, 2013).