Organohalogen concentrations and a gross and histologic ...

Frequency (%)
100
80
60
40
20
Severe
0
Moderate
Mild
organohalogens as well. Furthermore, the indications of the prevalence of
moderate and severe changes being higher in old females - when compared
to old males (Fig. 8) - could indicate that adult female polar bears are more
systemic exposed to organohalogens due to adipose mobilization and storage
dynamics associated with reproductive cycle periods of fasting and lactation
(e.g. Polischuk et al. 1995, 2002).
Sonne-Hansen et al. (2002) investigated renal lesions in North West Greenland
ringed seals in relation to cadmium toxicity. These seals were later
analysed for ∑-PCBs and ∑-DDTs (Table 8) and the histopathological
changes found in that study resembled some of those observed in the present
East Greenland polar bears. In Table 8 concentrations of organohalogen
compounds related to renal lesions in additional studies are listed and compared
to the subcutaneous adipose tissue concentration and exposure (intake)
of organohalogens East Greenland polar bears of the present studies. It
is seen that for each of the contaminant groups, solely, the concentration and
exposure of the East Greenland polar bears is lower compared to the studies
linking organohalogen compound exposure to renal lesions. However, the
bears have been long-term exposed for their entire lives including in utero
and neonatally in which the susceptibility to lesions is high.
In the renal tissue of the polar bear we found tubular protein droplets and
pigments which probably were related to the feed composition (e.g. plant
material) or season (fasting or hibernation) and/or a result of glomerular or
tubular lesions due to e.g. age, infections and maybe PCB exposure (Bruckner
et al. 1974a, b; Confer and Panciera 1995, MacLachlan and Cullen 1995,
Bergman et al. 2001). In the Baltic seals, hyperplasia of tubular epithelium
was found and related to estrogenic exposure of PCBs and DDTs (Bergman
et al. 2001). Compared to the Baltic grey and ringed seals the levels in the
present polar bears were significantly lower, which could explain that we
did not find such severe kidney lesions (Blomkvist et al. 1992, Bergman et al.
2001) (Table 8). In addition, we did not have non-exposed polar bear reference
material while the Baltic seal studies had non-exposed zoo seals and relatively
low-exposed seals from Svalbard.
18
16
14
12
10
8
6
4
2
0
Sub Ad. M Ad. F Old M Old F
Mild Moderate Severe
Age/sex groups Group of renal lesions
Sub Ad. M Ad. F Old M Old F
0 3 3 1 4
16 5 4 0 2
34 7 9 3 0
Figure 8
Left: Prevalence (%) of renal lesions in 91 East Greenland polar bears sampled from 1999 to 2002. The lesions are divided by degree
of severity (mild, moderate and severe) and age/sex (subadults, adult females and adult males). No. of observations are given
in the table. Right: Mean age (years) of the individuals categorised into mild, moderate and severe renal lesions. SD shown at the
top. Adult males: ≥ 6 years, adult females ≥ 5 years, old males and females: ≥ 15 years and others as subadults.
Age (years)
45