Environmental Engineering Reference
In-Depth Information
this last sentence why scientists working with POPs are casting a worried eye on climate
warming.
2. Are POPs being accumulated in biota (the biological part of the ecosystem) far
from source regions?
POPs are thought to have the potential to cause impacts on biota at
concentrations expressed often in parts per billion or even parts per trillion. This means
that environmental chemists are frequently operating at close to the detection limits of their
equipment. Great care must be taken in sampling and analytical procedures. Frequent inter-
laboratory comparisons are needed to ensure continuity and comparability between labor-
atories when investigating changes in levels in biological material between regions (spa-
tial) or over time (temporal). One of AMAP's first tasks was to establish procedures to help
compare data from different laboratories. Even today, achieving data comparability from
different organisations remains a challenge, but back in the 1980s and early 1990s, this
difficulty severely limited the ability to assess circumpolar data. Consequently, the 1994
POPs state of knowledge report was able to show that most POPs could be found in biota
throughout the UNECE region, including North America, Europe and the former Soviet
Union, but it was cautious about making comparisons. Nevertheless, it explained that al-
though levels were generally highest in industrial catchment areas (such as the Great Lakes
and the mouth of the River Rhine), another factor was at play. The longer the food chain,
the higher the degree of biomagnification and the higher the pollutant body burdens in
fatty tissues. Some top trophic Arctic predators carried similar concentrations as were be-
ing measured in the most heavily polluted industrial areas.
3. Should there be concern for deleterious impacts associated with POPs levels mainly
attributable to atmospheric transport?
The task force report began its answer by pointing
out that it is very difficult to prove or disprove that a POP in the environment is responsible
fordisease orachangeinterrestrial, aquatic orhumanpopulations andthatexposurewould
always be to a mixture of similar POPs anyway. In practice, a weight of evidence rationale
is used. This includes comparing “health” outcomes from dose response relationships in
controlled laboratory studies with observations from wildlife or from human populations
that are environmentally exposed to high levels of the pollutant. It showed that the main
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