Biotransformation of Individual Pesticides: Some Examples - Pesticide Biotransformation and Disposition - page 192

9

CHAPTER

Biotransformation of Individual
Pesticides: Some Examples

Ernest Hodgson
North Carolina State University, Raleigh, NC, USA

OUTLINE
Introduction

195

Selected Pesticides 195

Carbamate Insecticides—Carbaryl 195

Organochlorine Insecticides—DDT 197

Organophosphorus Insecticides 199

Chlorpyrifos 199

Phorate 199

Neonicotinoid Insecticides—Imidacloprid 199

Phenylpyrazole Insecticides—Fipronil 202

Pyrethroid Insecticides—Permethrin 202

Chloroacetamide Herbicides—Alachlor and Butachlor 205

Triazine Herbicides—Atrazine 207

Conclusions 207

Acknowledgments 207

References 207

INTRODUCTION
This chapter is intended to show how the general features of pesticide metabolism are
expressed in surrogate species and, in some cases, in humans, using individual, well-
known pesticides as examples. Of particular interest is the integration of the role of
several phase I and/or phase II enzymes to effect the overall metabolism of a single
chemical entity. In several cases both detoxication and activation pathways are apparent.

SELECTED PESTICIDES
Carbamate Insecticides—Carbaryl
Carbaryl (chemical name 1-naphthalenyl methylcarbamate, CAS No. 63-25-2) is sold
under many trade names, the most common being Sevin. It is widely used in agriculture,
in horticulture, and in residential settings. The primary mechanism of action is reversible
inhibition of acetylcholinesterase and it is generally regarded as being safe with respect to
human health. Metabolism in the rat is shown in Figure 9.1 ( Blacker et al., 2010 ).