Organohalogen concentrations and a gross and histologic ...

Introduction
Polar bears (Ursus maritimus) from East Greenland, Svalbard and the Kara
Sea carry higher loads of anthropogenic organohalogen compounds (e.g.
PCBs; polychlorinated biphenyls) than polar bears elsewhere in the Arctic
(e.g. Bernhoft et al., 1997; Norstrom et al., 1988, 1998; de March et al., 1998;
Andersen et al., 2001; AMAP, 2004) as these three areas receive air- and seaborn
pollutants from the same lower latitudinal sources. PCB levels this high
are in the range believed to negatively affect reproduction and survival of
seals in the Baltic Sea (e.g. de March et al., 1998; AMAP, 2004; Bergman and
Olsson, 1985; Swart et al., 1994; Ross et al., 1995, 1996, ). Organohalogens are
transferred transplacentally from mother to fetus in mammals (e.g. Bernhoft
et al., 1997; Polischuk et al., 2002) and act as agonists and/or antagonists to
hormones in endocrine organs and tissues (de March et al, 1998; AMAP,
2004; Colborn et al., 1993; Damstra et al., 2002).
In organohalogen dose-response and case-control experiments, toxic effects
on renal and adrenal histology have been found in rats (Bruckner et al.,
1974a, b; McCormack et al., 1978; Brandt et al., 1992; Wade et al., 2002),
bream fish (Abramis brama) and asp fish (Aspius aspius) (Koponen et al, 2001).
Studies of free-ranging grey seals (Halichoerus grypus) and ringed seals
(Phoca hispida) from the Baltic (Bergman and Olsson, 1985; Bergman et al,
2001) have shown an association between organochlorines and renal and
adrenal lesions. Damage to the proximal kidney tubules and adrenals can induce
demineralisation of the skeletal system (Fanconi’s syndrome) leading
to renal osteodystrophy (osteoporosis) (Friberg et al., 1986; WHO, 1992).
Specific to polar bears, recent studies on PCB levels in bears from Svalbard
indicated endocrine disruption of plasma testosterone in males, plasma progesterone
in females, plasma retinol (vitamin A) and T4 (Skaare et al., 2001;
Haave et al., 2003; Oskam et al., 2003). Additionally, high levels of organochlorines
were associated with low levels of IgG, suggesting possible immunotoxic
effects (Bernhoft et al., 2000; Lie et al., 2004, submitted).
Therefore samples of renal tissue from 91 bears and adrenals from 43 were
collected from East Greenland polar bears (Ursus maritimus) through local
subsistence hunters in the municipality of Scoresby Sound, 1999-2002. These
samples were examined histologically and correlated to individual levels of
organohalogens and to skull bone mineral density in a sub-set of 60 bears, to
evaluate the potentially chronic toxicity of these.
Materials and Methods
Sampling and preparation
Renal (n=91), adrenal (n=43) and subcutaneous adipose tissue (n=39) as well
as skulls (n=60) were sampled from polar bears by local subsistence hunters
in the Ittoqqortoormiit/Scoresby Sound area in central East Greenland
(69˚00’N to 74˚00’N) in 1999-2002. All samples were taken