BfR | Annual Report 2013
42
Pyrrolizidine alkaloids: carcinogenic and mutagenic
Knowledge regarding the toxicology of PAs is based on the observation
of health impairments in humans and livestock worldwide due to the
intake of plant varieties containing PAs (country-specific intake as food
or medication, contamination of food or feed) as well as on data from
relevant feeding trials.
Acute toxic effects were observed when PAs were ingested in larger
doses within a short space of time. In humans, these effects are mainly
seen in the liver in the form of veno-occlusive changes (veno-occlusive
disease, VOD). Enlarged hepatocytes are typical for the chronic liver tox-
icity of unsaturated PAs in animals. In a study to determine the chronic
effects of PAs, rats were given the 1,2-unsaturated pyrrolizidine alkaloid
riddelline via gavage. The substance induced the formation of tumours,
and a No-Observed-Adverse-Effect-Level (NOAEL) of 0.01 milligrams
PAs per kilogram bodyweight and day (mg/kg BW/day) was measured
for non-neoplastic changes.
Pyrrolizidine alkaloids are secondary plant substances produced by plants as protection against preda-
tors. Due to their health-damaging potential, 1,2-unsaturated pyrrolizidine alkaloids in particular are unde-
sirable in foods. The BfR is pursuing various research approaches to this issue: in a project to measure
pyrrolizidine alkaloids in food and feed, the BfR analysed different herbal tea and tea samples to determine
the concentration of 1,2-unsaturated pyrrolizidine alkaloids. These findings were evaluated in a preliminary
risk assessment, which the BfR published in July 2013. Alongside analytical aspects, investigations into
the absorption and the molecular effect mechanisms of pyrrolizidine alkaloids are a further core area of
research.
Pyrrolizidine alkaloids are secondary plant
substances produced by a large number of
plant varieties all over the world. Over 500
different pyrrolizidine alkaloids are known,
and their occurrence is expected in more
than 6,000 plant species. Plants containing
pyrrolizidine alkaloids primarily belong to the
aster family, roof leaf plants or legumes.
Due to their health-damaging potential,
1,2-unsaturated pyrrolizidine alkaloids (PAs)
in particular are undesirable in foods and
feeds. As food contaminants, they have pri-
marily been found to date in the European
food sector in honey and lettuce mixtures
containing wild herbs that form PAs. The BfR
has published risk assessments on these
topics.
Pyrrolizidine alkaloids
in herbal teas and teas
