Organohalogen concentrations and a gross and histologic ...

eproductive rates of seals in the Baltic Sea and endocrine disruptions (e.g.
Bergman and Olsson 1985; Colborn et al., 1993; Feldman 1995; Bergman 1999;
Damstra et al., 2002). Halogenated organic substances such as OCs and their
metabolites have been linked to adverse health effects in laboratory mammals,
birds as well as wildlife through interactions with immunologic, reproductive
and endocrine systems, as well as modulation of subcellular enzyme systems
and metabolism (Helle et al., 1976; Safe 1986; Bergman and Olsson, 1985; Tanabe
et al., 1987; Safe, 1991; Bergman et al., 1992; Safe, 1994; Swart et al., 1994;
Wiig et al., 1998; Bergman, 1999; O’Hara and O’Shea, 2001).
Polar bears mate in March-May (Rosing-Asvid et al., 2001) but active gestation
does not commence until September-October, when the pregnant female enters
the hibernation den (Ramsay and Stirling, 1988; Wiig et al., 1992). During hibernation
(October-March) the female is fasting (for up to 6 months) and is drawing
on her fat reserves (Lentfer, 1975). During this period, and until the cubs are
born around 1 January (Arnould and Ramsay, 1994), the OCs that have been
stored in the female’s peripheral tissue (primary fat) are released into the blood
stream, which may adversely affect the foetuses in utero. The cubs also receive
additional OCs via lactational transfer from their mother during suckling (Polischuk
et al., 1995, 2002; Takagi et al., 1976; Tanabe et al., 1982; Koppe et al., 1992;
Bernhoft et al., 1997). Polar bear milk has an average fat content of ca. 33%
(range: ca. 24 to ca. 48%; Jenness et al. 1972), and therefore a high OC load is
transferred to the cub during suckling , which may continue for up to 2 years
(Arnould and Ramsay, 1994; Oehme et al., 1995). Polar bears may also experience
periods when food is scarce or unavailable and, during such periods, the
proportion of adipose tissue may be reduced from 50% to 10% of the body mass
(Pond et al., 1992; Atkinson and Ramsay, 1995). Hence, the OC load of an individual
polar bear not only reflects the initial loads received in utero and during
infancy, but also the bears sex and age, and the season of the year (Bernhoft et
al., 1997; Muir et al., 1999; O’Hara and O’Shea, 2001; Polischuk et al., 1995, 2002).
The purpose of the present study was to determine the extent of change in OC
concentrations in the fat of East Greenland polar since 1990, and to investigate
how OC concentrations vary with age, sex and season. Fat samples were obtained
from 92 individual polar bears that were collected as part of the Inuit
hunt in central East Greenland during the period 1999-2001. Fat samples were
analysed for CBs, DDTs, chlordanes, dieldrin, hexachlorocyclohexanes (HCHs)
and chlorobenzenes (CBz).
Materials and Methods
Sampling
Fat samples from polar bears were collected by local subsistence hunters in
the Ittoqqortoormiit/ Scoresby Sound area in central East Greenland between
69˚00’N and 74˚00’N, 19˚00’W and 24˚00’W in 1999-2001. All tissue
samples were taken as soon as possible post mortem and stored in separate
polyethylene (PE) Whirlpak bags. All samples were kept at outdoor temperature
(-5 to -20 ºC) until transferred to a freezer (-10 to -20 ºC). Samples
were shipped frozen from Scoresby Sound to Roskilde, where the portion of
fat that had been in contact with the PE was trimmed off and the remaining
part was transferred to precleaned glass containers with cleaned aluminum
foil in between the lid and the glass container. Further storage was at -20 ºC.
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