Environmental Engineering Reference
In-Depth Information
Atmosphere
E uents
Leaching
Surface runoff
Water
Fishes
Rooted
Sediment
FIGURE 13.1
Dynamic movement of pesticides in the aquatic environment.
eastern parts of Europe (Jaward et al. 2004). As a result of all these pathways, pesticides
are widely found in rivers. OCPs cause major damage to aquatic life (Van der Werf 1996).
Pimentel et al. (1993) estimated that from 1977 to 1987 in the United States, 6-14 million fish
per year were killed by pesticides.
13.2.1  Hazards of Pesticide Residues in Water
The two main hazards of pesticide residues in water are the deposition of chemicals in
the bodies of fish, which are effective filters of suspended particulate matter, and in the
bodies of aquatic organisms that form the food for the fish, and as a result of both, more
chemical gets deposited in the fish than is found free in water. The accumulation of pes-
ticides in fish is of great importance because they form food for humans and birds. OCPs
are characterized by high persistence, low polarity, low aqueous solubility, and high lipid
solubility (lipophilicity), and as a result, they have a potential to bioaccumulate in fish and
in the food chain, posing a great threat to human health and the environment globally
(Lars 2000). For example, omega-3 fatty acids offer excellent health benefits, but they come
from the fatty tissues of fish, which are also the best part of the fish to store pesticides.
Problems occur when people who want to improve their health naturally rely on omega-3
fatty acids but unknowingly ingest high amounts of pesticides. It is known that OCPs
in water are taken up very rapidly by living organisms. Holden (1962) and Marth (1965)
demonstrated that fish can take up 80%-90% of the DDT from water through gills. It is
therefore important to determine the levels of OCP residues in fish samples, considering
the adverse health effects OCPs cause in humans.
13.3 Fish Exposed to Pesticides
Fish and aquatic animals are exposed to pesticides in three primary ways: (1) dermally, direct
absorption through the skin by swimming in pesticide-contaminated waters, (2) breathing, by
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