Volume 18 of the Handbook of Psychopharmacology represents the first of a series of volumes intended to bring earlier sections of the work up to date. Volumes 7, 8, and 9, published in 1977 and 1978, dealt with principles of behavior, drugs and neurotransmitters, and neuroanatomy. In subsequent volumes dedicated to these issues, a mixture of topics will be covered in a given volume, covering both advances in basic knowledge in these three areas of the subject and reviews of theoretical and meth odological issues deemed to be of particular relevance at present. L. L. !. S. D. !. S. H. S. vii CONTENTS CHAPTER 1 Behavior as a Measure of Adverse Responses to Environmental Contaminants BERNARD WEISS 1. Special Perspectives 1 1. 1. Pharmacology and Toxicology. 1 1. 2. Origins of Behavioral Toxicology. 2 1. 3. Special Problems 2 2. Specific Substances. 5 2. 1. Heavy Metals 5 2. 2. Volatile Solvents 20 2. 3. Pesticides. 33 2. 4. Air Pollutants 36 2. 5. Nonspecific Poisons. 42 2. 6. Food Additives 44 3. Future Prospects 47 3. 1. Chemical Waste. 47 3. 2. Susceptible Populations. 48 3. 3. The Statistics of Risk. 49 3. 4. Screening 49 3. 5. Implications for Psychopharmacology 51 4. References. 51 CHAPTER 2 State Dependent Learning and Drug Discriminations DONALD A. OVERTON 1. Introduction. 59 2. Description of State Dependent Learning. 59 ix x CONTENTS 3. History of Development of Knowledge about SDL 60 3. 1. Nineteenth Century Reports.