Radiolabelled pesticides are used: in studies involving improved formulations of pesticides, to assist in developing standard residue analytical methodology, and in obtaining metabolism data to support registration of pesticides. This manual is designed to give the scientist involved in pesticide research the basic terms and principles for understanding the detection and measurement of ionizing radiation, its hazards, and some of the more common applications. The manual is divided into six parts. Part I provides a general introduction to experimental work with isotopes and radiation, reviewing various aspects of atomic physics and radiation measurements. Part II reviews basic concepts of radiation biology. Part III consists of a series of review questions. Part IV is an introduction to practical work, examining such areas as experimental design, statistics, safety, and waste disposal. Part V consists of two sections, a set of basic laboratory exercises and a set of applied exercises. Statement of purpose, list of materials needed, and procedures are provided for each of these exercises. Part VI consists of 10 appendices which include information on radioactive waste disposal and sources of radiolabelled chemicals. Part VII is a glossary of basic terms and concepts. (JN)