Organohalogen concentrations and a gross and histologic ...

have the potential for adverse health effects, e.g. on growth and development
(Takagi et al. 1976, Tanabe et al. 1982, Koppe et al. 1992, Birnbaum 1994,
Polischuk et al. 1995, Bernhoft et al. 1997, Polischuk et al. 2002).
Various organohalogens have been linked to dysosteogenesis (periodontose)
in mammal wildlife (Zakharov and Yablokov 1990, Bergman et al. 1992,
Mortensen et al. 1992, Schandorff 1997a) and in the laboratory (Render et al.
2000a,b, Render et al. 2001). In various mammalian wildlife, periodontitis in
skull and mandibles during distinct periods of exposure to anthropogenic
pollutants have been examined in e.g. grey seal (Halichoerus grypus), ringed
seal (Phoca hispida) and harbour seal (Phoca vitulina) (Zakharov and Yablokov
1990, Bergman et al. 1992, Mortensen et al. 1992, Schandorff 1997a-b). These
studies showed relationhips between organohalogens and exostosis, periodontitis,
loss of alveolar bone structures, osteoporosis, widening of the canine
opening and enlargement of the foramen mentalia.
Polar bears (Ursus maritimus) from East Greenland, Svalbard and the Kara Sea
carry higher loads of organohalogens than polar bears elsewhere in the Arctic
due to their reliance on blubber from ringed seal (P. hispida) and bearded seal
(Erignathus barbatus) (e.g. Bernhoft et al. 1997; Dietz et al. 2004, de March et al.
1998, Norstrom et al. 1988, 1998; Andersen et al. 2001, Derocher et al. 2002, Lie
et al. 2003, AMAP 2004). Recent studies of polar bears from Svalbard have
indicated that high levels of organohalogens negatively affect retinol (vitamin
A) and thyroid levels (Skaare et al. 2001) and possibly also negatively affect on
sex steroids and reproductive organs (female pseudohermaphrodites) - although
these latter mechanisms are not clearly understood (Wiig et al. 1998,
Haave et al. 2003, Oskam et al. 2003, Sonne et al. In press). Other studies have
associated high levels of organohalogens with low levels of IgG suggesting a
possible immunotoxic effects on the IgG answer (Bernhoft et al. 2000, Lie et al.
2004, Lie et al. submitted). Overall, these studies support the notion that organohalogens
may cause endocrine disruption in the polar bear and thereby
potentially lower the immune response.
To determine whether exposure to organohalogens may have contributed to
periodontitis and alveolar bone structure, 272 East Greenland polar skulls
collected from 1892 to 2002 were compared to detect a time trend in the
prevalence between the period without pollution (1892-1960) and with pollution
(1961-2002). Finally, the prevalence of periodontitis in a subset of 79
individuals was analysed in relation to individual adipose body burden of
various organohalogens.
Materials and methods
Sampling and preparation
A sample of 272 skulls and 52 bacula from East Greenland (sampled between
Skjoldungen at 63º15’N and Danmarks Havn at 76º30’N) was studied.
The specimens had been sampled by scientific expeditions (n=167) from
1892 to 1987 and stored at the Zoological Museum in Copenhagen (Denmark)
and during our recent collection (n=105) with the assistance of local
hunters in Scoresby Sound (ca. 71 ºN), 1999 to 2002. The preparation method
of the “historical” specimens and the recently sampled skulls and bacula
were macerated and boiled so that muscles and tendons could be removed
gently prior to H 2 O 2 oxidation for 24 to 48 hours. Samples of subcutaneous
adipose tissues from the 105 newly sampled bears were shipped frozen from
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