Organohalogen concentrations and a gross and histologic ...

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sis suggested that firm conclusions could not be drawn regarding the general
time trend based on these two sampling periods. The range of half-lives
of the various OC classes were estimated to lie between 4.5 and 20.6 years
depending on the age and sex groups considered.
Keywords: Polar bear, Ursus maritimus, East Greenland, organochlorines,
OCs, DDTs, PCBs, Chlordanes, Dieldrin, Hexachlorocyclohexane, Chlorobenzenes,
seasonal and temporal variation.
*Corresponding author Tel. +45-46-30-19-38; fax: +45-46-30-19-38 Email address:
rdi@dmu.dk (R. Dietz)
Introduction
Since the 1950s, large quantities of organochlorine (OC) contaminants such
as chlorinated pesticides (dichlorodiphenyltrichloroethanes (DDTs), chlordanes
(CHLs), hexachloorcyclohexanes (HCHs), toxaphenes), industrial
products (PCBs) and by-products (hexachlorobenzene (HCB), chlorinated
dioxins and furans) have been released into the atmosphere in the Northern
Hemisphere. The persistence and lipophility of these OCs has resulted in
their accumulation in animals in the Arctic marine environment following
long-range atmospheric transport from their areas of use in the midlatitudes
of Europe, Asia and North America. The polar bear is one of the
most exposed species of the Arctic biota and, in a variety of Arctic marine
biota, the highest OC concentrations have generally been found in the East
Greenland, Svalbard and Kara Sea areas (de March et al., 1998; AMAP,
2004).
OCs concentrate through Arctic marine foodwebs, and are stored in the adipose
tissue due to their high lipophilicity and persistence. Tissues of polar
bears (Ursus maritimus) contain some of the highest OC levels in the Arctic
and the Arctic Monitoring and Assessment Programme (AMAP) has therefore
recommended that special attention be paid to this species (de March et
al., 1998). Polar bears are reliant on a high fat (lipid) diet derived from their
primary prey, ringed seal (Phoca hispida), and to a lesser extent from bearded
seals (Erignathus barbatus) (Stirling and Archibald, 1977; Smith, 1980). In
particular, high levels of OCs are found in polar bear and ringed seals from
populations in the eastern Atlantic Arctic (Norstrom et al., 1988; Norheim et
al., 1992; Kleivane et al., 1994; Norstrom and Muir, 1994; de March et al.,
1998; Norstrom et al., 1998; Muir and Norstrom, 2000; Andersen et al., 2001;
Kucklick et al., 2002).
OCs were first detected in polar bears in 1975, in fat samples of individuals
taken from Cornwallis Island and southern Hudson Bay, Canada and western
Greenland (Bowes and Jonkel, 1975; Clausen and Berg, 1975). Subsequently,
OC residues have been detected in polar bears from most Arctic
areas (Norstrom et al., 1988; Norheim et al., 1992; Kleivane et al., 1994;
Letcher et al. 1995a, 1995b; Letcher et al., 1998; Norstrom and Muir 1994;
Norstrom et al., 1998; Muir and Norstrom 2000; Andersen et al., 2001; Kucklick
et al., 2002). Overall, concentrations of chlorobiphenyls (CBs) and chlordanes
(and metabolites such as oxychlordanes) have been found to be quite
high, whilst DDT and HCH are relatively low.
Concentrations of OCs in some individual polar bears from East Greenland
and Svalbard were similar to those suspected to have led to a reduction in the