Distribution and Effects of Chemicals in Communities and Ecosystems - Organic Pollutants: An Ecotoxicological Perspective - page 98

4.9 Summary
The movement of organic pollutants along food chains, and their fate in soils and
sediments, is dependent upon biological as well as chemical factors. The chemical
and biochemical properties of pollutants determine the rates at which they move
between compartments of the environment, cross membranous barriers, or undergo
chemical or biochemical degradation. Highly lipophilic compounds with high K ow
values are of particular concern because they tend to be immobile and persistent in
soils and sediments. Where they are chemically stable and resist metabolic degrada-
tion, they tend to be biomagnified in food chains, reaching relatively high concen-
trations in top predators. Examples include persistent OC insecticides and PCBs,
PCDDs, PCDFs, and methyl mercury.
In the field, effects of chemicals upon individuals may be measured by the use
of mechanistic biomarkers. This approach has recently been strengthened by new
technologies arising in the field of genomics. Free-living or deployed organisms may
be sampled in order to measure responses to environmental chemicals.
In ecotoxicology, the largest concern is about effects of organic pollutants at the
levels of population, community, and ecosystem. Population effects may be on num-
bers (population dynamics) or on gene frequencies (population genetics). Data on
effects upon individuals obtained by using biomarker assays can provide vital evi-
dence of causality at the population level and above when conducting field studies.
In communities and in ecosystems there may be effects on either or both structure
and function. The potential use of population models incorporating biomarker data
for studying pollutant effects is discussed.
furtHer readIng
Burczynski, M. (Ed.) (2003). An Introduction to Toxicogenomics —Describes, with examples,
the use of genomic techniques in toxicology.
Newman, M.C and Unger, M.A. (2003). Fundamentals of Ecotoxicology , 2nd edition—A
valuable account of ecological effects of pollutants.
Peakall, D.B. (1992). Animal Biomarkers as Pollution Indicators —A wide-ranging account of
biomarker assays in higher animals.
Peakall, D.B. and Shugart, L.R. (Eds.) (1993). Biomarkers: Research and Application in the
Assessment of Environmental Health —Conclusions and statements of principle from a
NATO Symposium.
Schuurmann, G. and Markert, B. (Eds.) (1998). Ecotoxicology —A multiauthor work giving a
very detailed account of the environmental fate of certain chemicals.