The livers of
polar bears,
walruses,
bearded seals, and
huskies can contain very high levels of preformed vitamin A, and their consumption has led to vitamin A poisoning (
hypervitaminosis A) according to several
anecdotal reports. It has been estimated that consumption of 500 grams of polar bear liver would result in a toxic dose for a human. Also, in 1913,
Antarctic explorers on the
Far Eastern Party Douglas Mawson and
Xavier Mertz were believed to have been poisoned, the latter fatally, from eating husky liver, though this claim has been recently contested. Mercury content in some species can also be an issue. In 2012, the Government of
Nunavut, Canada warned pregnant women to lower their intake of
ringed seal liver due to elevated levels of
organomercury. The
neurotoxin in the liver of the
pufferfish (which is consumed in
Japanese cuisine as
fugu, tightly regulated by Japanese law) contains the highest concentration of the
tetrodotoxin, which characterizes the species. Consequently, the liver has been illegal to serve since 1984. ==Traditions==