The Davis Strait - DCE - Nationalt Center for Miljø og Energi

7.2 Conclusions on contaminant levels
In general, the AMAP studies have revealed that levels of organochlorines in
Arctic biota are highest in the marine organisms belonging to the top trophic
level (e.g. whales). This is particularly true in relation to bio-magnification of
PCBs and DDT. AMAP activities have also shown a decrease in the levels of
some POPs (e.g. PCBs and DDT), resulting from introduction of bans and restrictions
relating to their use in other parts of the world (AMAP 2004, Muir
& de Wit 2010). At the same time, however, levels of new persistent pollutants,
such as brominated flame retardants, are on the increase (AMAP 2004,
Muir & de Wit 2010), also in animals from Greenland. Levels of petroleum
compounds, including PAHs, are relatively low in the Greenland environment
and are regarded as background concentrations.
The short overview given in this section documents that our present
knowledge on contaminant levels in marine organisms from West Greenland
and the assessment area is still limited. Further studies are needed to
understand better whether and to what degree the biota in the assessment
area are already impacted by contaminants, but also to serve as a baseline
for future monitoring and assessments. In this respect it is important to learn
more about the relationship between contaminant loads and potential biological
impact, including sublethal health effects or impairments.
7.3 Biological effects
The research and monitoring activities described in the previous section
clearly indicate the presence of different kinds of contaminants (e.g. POPs,
heavy metals) in biota from Greenland. Regional differences in contaminant
level have been found as well as differences between species, with highest
concentrations apparent in top predators (e.g. polar bear, seals). However,
contaminant levels are often still lower than in biota from more temperate
regions, e.g. the North Sea or Baltic Sea. The question arises of whether the
levels found in the Arctic are sufficiently high to cause biological effects and
what the threshold level of impact might be.
Threshold levels have been estimated for various contaminants in a range of
species both under laboratory conditions and in the field in European waters.
These studies have clearly indicated that organisms are affected by contaminants
and that their physiological responses depend on the duration
and extent of exposure. The effects observed range from enzyme inhibition
and changes in cellular processes, to immuno-suppression, neurotoxic and
genotoxic effects up to reproduction impairment or histopathology alterations
as endpoint of the pollutant impact. Differences in response have been
demontrated among species and regions (Van der Oost et al. 2003, Lehtonen
et al. 2006, Picado et al. 2007). Toxicity tests have also widely been used in
temperate regions to relate environmental concentrations to biological effects,
but very few tests have been published on polar species.
Species living in the Arctic and Sub-Arctic have very specific life strategies
and population dynamics as a result of adaptation to the harsh environment.
Moreover, their fat content and seasonal turnover can differ when compared
to more temperate species (AMAP 2004). The lower temperatures in Greenlandic
waters are also likely to have an impact on the toxicity of contaminants.
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