Organohalogen concentrations and a gross and histologic ...

Paper IV
Liver histology of free-ranging East Greenland
polar bears (Ursus maritimus) in
relation to organohalogen exposure
Sonne C. 1,2* , R. Dietz 1 , P. S. Leifsson 3 , E. W. Born 4 , R. J. Letcher 5 , M.
Kirkegaard 1
, D. C. G. Muir 6
, F. F. Riget 1
and L. Hyldstrup 7
1
Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399,
DK-4000 Roskilde, Denmark
2
Department of Basic Animal and Veterinary Sciences, The Royal Veterinary and Agricultural University,
Bülowsvej 17, DK-1870 Frederiksberg C, Denmark
3
Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, Bülowsvej
17, DK-1870 Frederiksberg, Denmark
4
Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland, Denmark
5
Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Onatrio, Canada
N9B 3P4
6
National Water Research Institute, Environment Canada, Burlington, Ontario, Canada L7R 4A6
7
University Hospital of Hvidovre, Kettegaards Allé 30, DK-2650 Hvidovre, Denmark
* Corresponding author Tel. +45-46-30-19-54; fax: +45-46-30-19-14; Email
address: csh@dmu.dk (C. Sonne)
Summary
The liver histology of 34 subadult, 29 adult female and 25 adult male polar
bears (Ursus maritimus) sampled in East Greenland during 1999-2002 were
studied to evaluate the toxicity of anthropogenic organohalogens (PCBs,
DDTs, CHLs, dieldrin, HCHs, HCB and PBDEs). Lightmicroscopic findings
were nuclear displacement from normal, central cytoplasmic location in parenchymal
cells, mononuclear cell infiltrations (mainly portally and as granulomas),
bile duct proliferations, portal fibrosis and fat accumulation in
hepatocytes and prominar Ito-cells. Of these, portal fibrosis was found to be
positively correlated with age while bile duct proliferation was highly correlated
to the degree of portal fibrosis (some seasonal variations were found as
well). Significant differences in mean concentrations of ∑-DDTs was found
between groups of histological changes but these were thought to be a result
of low sample size. To our knowledge this is a first time evaluation of liver
histology in relation to organohalogen concentrations in mammalian wildlife
species and the signs of chronic hepatitis, also in relation to Glisson’s
triads, is probably natural events in the East Greenland polar bear from
ageing, infectious agents, lipid hyperphagia and fasting, but long-term exposure
to mercury and organohalogen compounds cannot be ruled out as cofactors.
Key words: polar bear, Ursus maritimus, East Greenland, PCBs, DDTs, liver,
bile duct proliferation, portal fibrosis, lipid granulomas, Ito cells.
Introduction
In marine wildlife, chronic exposure to organohalogens (e.g. PCBs and
DDTs) has been associated with toxic effects on several organ systems (Bergman
and Olsson 1985, Bergman 1999, Bergman et al., 2001, Schumacher et
143