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Degradation of Pesticides by Animals
H. Wyman Dorough and Sue K. Ballard
1. 1. INTRODUCTION
Once a pesticide enters the animal body through ingestion, inhalation, or dermal
absorption, it is subject to metabolism by a variety of mechanisms. The types
of chemical or biochemical transformations a pesticide may undergo in the animal
are varied, and knowledge of the fate of these toxicants in animals contributes
to a better understanding of their advantages and limitations for specific use
situations. This is an important consideration since the almost universal usage
of wide varieties of pesticides may result in the exposure of man and other
nontarget organisms on a regular basis. The effect of this exposure on animals
depends upon many factors such as the concentration and chemical composition
of the pesticide, the species of animal, and the sex and age of the animal. While
complete coverage of the fate of pesticides in animals exceeds the intent of the
present presentation, a general discussion of the biochemistry of pesticides in
animals is necessary if one is to gain even the slightest appreciation of the
complexity of the many factors involved.
Basically, the various types of pesticides (e.g., herbicides, insecticides,
fungicides) may be considered essentially as lipophilic compounds containing
certain functional groups that may undergo well-recognized biochemical reactions. For the most part, these reactions lead to compounds that are more polar
than the parent molecule and more easily excreted from the body. Therefore,
most metabolic transformations of pesticides are detoxification processes. It is
well-established, however, that metabolism often leads to more active comH. Wyman Dorough and Sue K. Ballard • Department of Entomology and Graduate Center
for Toxicology, University of Kentucky, Lexington, Kentucky 40546.
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Degradation of Pesticides by Animals
H. Wyman Dorough and Sue K. Ballard
1. 1. INTRODUCTION
Once a pesticide enters the animal body through ingestion, inhalation, or dermal
absorption, it is subject to metabolism by a variety of mechanisms. The types
of chemical or biochemical transformations a pesticide may undergo in the animal
are varied, and knowledge of the fate of these toxicants in animals contributes
to a better understanding of their advantages and limitations for specific use
situations. This is an important consideration since the almost universal usage
of wide varieties of pesticides may result in the exposure of man and other
nontarget organisms on a regular basis. The effect of this exposure on animals
depends upon many factors such as the concentration and chemical composition
of the pesticide, the species of animal, and the sex and age of the animal. While
complete coverage of the fate of pesticides in animals exceeds the intent of the
present presentation, a general discussion of the biochemistry of pesticides in
animals is necessary if one is to gain even the slightest appreciation of the
complexity of the many factors involved.
Basically, the various types of pesticides (e.g., herbicides, insecticides,
fungicides) may be considered essentially as lipophilic compounds containing
certain functional groups that may undergo well-recognized biochemical reactions. For the most part, these reactions lead to compounds that are more polar
than the parent molecule and more easily excreted from the body. Therefore,
most metabolic transformations of pesticides are detoxification processes. It is
well-established, however, that metabolism often leads to more active comH. Wyman Dorough and Sue K. Ballard • Department of Entomology and Graduate Center
for Toxicology, University of Kentucky, Lexington, Kentucky 40546.
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