Organohalogen concentrations and a gross and histologic ...

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Chapter 5
Histology of East Greenland renal tissue
and adrenals sampled during 1999-2002
Kidney and adrenal investigations were based on tissue samples from 91
and 43 bears, respectively, killed in Inuit hunts in East Greenland during
1999-2002 (the histological examination followed the one for liver tissue,
Chapter 4). In the evaluation of toxicity and histopathological changes, these
were analysed in relation to individual levels of organohalogens in adipose
tissue (∑-PCBs, ∑-DDTs, ∑-CHLs, dieldrin, ∑-HCHs, HCB and ∑-PBDEs).
Damage to proximal kidney tubules, as well as Cushing’s syndrome, can
induce demineralisation of the skeletal system (Fanconi’s syndrome) leading
to osteoporosis (Friberg 1986, WHO 1992). Therefore bone mineral density
was analysed in a sub-set of 56 bears in relation to renal histopathological
changes. These results are described in details in paper V.
Renal lesions
Of the 91 individuals examined, 38 (42%) exhibited glomerular basement
membrane thickening (glomerulonephritis and -sclerosis) and different degrees
of mesangial deposits. In most of these, hyalinisation of tubular basement
membrane (accompanied by atrophy and fibrosis) and glomerular
sclerosis were often present while tubular protein droplet accumulations
and PAS-positive pigments (e.g. bile pigment, melanin, haemoglobin or
byproducts from the metabolism of plant material but not lipofuscin or
haemosiderin) were found in nearly all individuals. In one 7-year-old male
tubular cell proliferation at the corticomedullary border was found as well.
There was a clear age dependency for severe glomerular and tubular lesions,
and indications of old females having a higher prevalence of moderate and
severe changes when compared to old males (Fig. 8). However, this could
not be evaluated statistically due to a relatively low sample size in these two
groups.
The renal histological changes found in the glomeruli in the present study
were similar to those induced by organohalogens – and heavy metals - in
controlled laboratory experiments and humans (e.g. McCormack et al. 1978,
WHO 1992, Maxie 1993, Rao et al. 1993, Churg et al. 1995, Confer and Panciera
1995, Cotran et al. 1999, Wade et al. 2002). The histopathological
changes found in the glomeruli and mesangium of the bears were also to
some degree similar to those found in Baltic grey seals and ringed seals exposed
to high concentrations of organohalogens during the period 1977-1996
(Bergman and Olsson 1985, Bergman et al. 2001) as well as in as free-ranging
Atlantic bottlenose dolphins (Tursiops truncatus) (Rawson et al. 1993) and
Arctic beluga whales (Delphinapterus leucas) (Woshner et al. 2002) exposed to
mercury. Based on a reference material from zoological gardens and Svalbard
(non and low polluted, respectively), as well as a large time trend study
over the entire period 1977-1996, Bergman and Olsson (1985) revealed a
plausible effect of age and chronic exposure to PCBs and DDTs on kidney
histology (the relations to individual levels of organohalogens was investigated
as well). The same age relations were found in the present study,
and based on time trend studies in East Greenland (e.g. AMAP 2004, Dietz et
al. 2004), the renal lesions in the polar bears may be explained by age and