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Polar bears, along with other fish-eating carnivores of the polar regions, concentrate large amounts of vitamin A in their liver -- so much, in fact, that the livers of polar bears, seals, and even huskies can be toxic. Ingestion of polar bear livers and huskie livers has been reported to cause hypervitaminosis A in [[Polar Explorers]].
{|border = "1" style="text-align: center;" align="center"
|+ '''Vitamin A levels (Retinol, i.u./g) in the liver of various animals'''
! width =200 | Species
! width = 60 | n
! width = 100 | Average
! width = 100 | Maximum
! Reference
|-
! Polar Bear (Greenland)
| align = "center" | 3 || 16,300 || 18,000 ||Rohdal & Moore 1943
|-
! Polar Bear (Alaska)
| 2 || 32,600 || 34,600 || Russell 1966
|-
! Polar Bear (Alaska)
| 14 ||22,100 || 30,400 || Lewis & Lentfer 1967
|-
! Hooded Seal
| 40 || 3,000 || 24,000 || Rohdal & Davies 1949
|-
! Greenland Seal
| 70 || 3,441 || 15,000 || Rohdal & Davies 1949
|-
! Atlantic grey seal
| 1 || na || 1,550 || Rohdal & Davies 1949
|-
!Bowhead whale
| 1 || na || 4,320 || Lewis & Lentfer 1967
|-
!Bearded seal
| 1 || na || 1,780 ||Lewis & Lentfer 1967
|-
!Ringed seal
| 1 || na || 2.450 || Lewis & Lentfer 1967
|-
! Common seal
| 2 || 56 || 90 || Rohdal & Davies 1949
|-
!Domestic Cat
| 1 || na || 18 || Russell 1966
|-
|}
''NB: 1 international unit = 3.3 micrograms of retinol''
'''References'''
Rodahl, K., and T. Moore. 1943. The vitamin A content and toxicity of bear and seal liver. Biochemical Journal 37:16668. PMID 16747610
Rodahl, K. and A.W. Davies. 1949 Vitamin A in seals. Biochem J. 45:408-12. PMID 15394431
Rodahl, K. 1949. Toxicity of polar bear liver. Nature 164:530.
Russell, F. E. 1967. Vitamin A content of polar bear liver. Toxicon 5:6162. PMID 6036254
Lewis, R. W., and J. A. Lentfer. 1967. The vitamin A content of polar bear liver: range and variability. Compar. Biochem. Physiol. 22:923-926.
Southcott R, Chesterfield N, Lugg D. Vitamin A content in the livers of huskies and some seals from Antarctic and subantarctic regions. Med J Aust 1971; 1: 311-313.
{|border = "1" style="text-align: center;" align="center"
|+ '''Vitamin A levels (Retinol, i.u./g) in the liver of various animals'''
! width =200 | Species
! width = 60 | n
! width = 100 | Average
! width = 100 | Maximum
! Reference
|-
! Polar Bear (Greenland)
| align = "center" | 3 || 16,300 || 18,000 ||Rohdal & Moore 1943
|-
! Polar Bear (Alaska)
| 2 || 32,600 || 34,600 || Russell 1966
|-
! Polar Bear (Alaska)
| 14 ||22,100 || 30,400 || Lewis & Lentfer 1967
|-
! Hooded Seal
| 40 || 3,000 || 24,000 || Rohdal & Davies 1949
|-
! Greenland Seal
| 70 || 3,441 || 15,000 || Rohdal & Davies 1949
|-
! Atlantic grey seal
| 1 || na || 1,550 || Rohdal & Davies 1949
|-
!Bowhead whale
| 1 || na || 4,320 || Lewis & Lentfer 1967
|-
!Bearded seal
| 1 || na || 1,780 ||Lewis & Lentfer 1967
|-
!Ringed seal
| 1 || na || 2.450 || Lewis & Lentfer 1967
|-
! Common seal
| 2 || 56 || 90 || Rohdal & Davies 1949
|-
!Domestic Cat
| 1 || na || 18 || Russell 1966
|-
|}
''NB: 1 international unit = 3.3 micrograms of retinol''
'''References'''
Rodahl, K., and T. Moore. 1943. The vitamin A content and toxicity of bear and seal liver. Biochemical Journal 37:16668. PMID 16747610
Rodahl, K. and A.W. Davies. 1949 Vitamin A in seals. Biochem J. 45:408-12. PMID 15394431
Rodahl, K. 1949. Toxicity of polar bear liver. Nature 164:530.
Russell, F. E. 1967. Vitamin A content of polar bear liver. Toxicon 5:6162. PMID 6036254
Lewis, R. W., and J. A. Lentfer. 1967. The vitamin A content of polar bear liver: range and variability. Compar. Biochem. Physiol. 22:923-926.
Southcott R, Chesterfield N, Lugg D. Vitamin A content in the livers of huskies and some seals from Antarctic and subantarctic regions. Med J Aust 1971; 1: 311-313.