Jianya Huan has written:

'Species difference in bioactivation and detoxification of pyrrolizidine (senecionine) alkaloids' -- subject(s): Pyrrolizidines

'Effects of dietary pyrrolizidine alkaloids on copper and vitamin A metabolism in the chicken and Japanese quail' -- subject(s): Pyrrolizidines, Chickens, Japanese quail

A. R. Mattocks has written:

'Chemistry and toxicology of pyrrolizidine alkaloids' -- subject(s): Pyrrolizidines, Toxicology

Contains small amounts of pyrrolizidine alkaloids which may be toxic to the liver even in small amounts. The long-term use in medicinal preparations is not recommended.

Not for pregnant or breast-feeding women. Not for internal useage as contains toxic pyrrolizidine alkaloids, possibly causing liver cancer. Not for deep wounds. Not to be used externally more than 4 weeks. And more . . .

Not to be used by pregnant, nursing women and children under 6 years. Avoid the internal use of coltsfoot, needs more studies. Contains pyrrolizidine alkaloids that could cause liver cancer in large doses. And more . . .