I. Metals.- 1 Methylmercury Neurotoxicity and Its Uptake Across the Blood—Brain Barrier.- 2 The Neurotoxicity of Methylmercury in the Developing Nervous System.- 3 Intestinal Absorption of Aluminum: Relation to Neurotoxicity.- 4 Aluminum Ingestion: A Risk Factor for Alzheimer’s Disease?.- 5 The Concept of Direct and Indirect Neurotoxicity and the Concept of Toxic Metal/Essential Element Interactions as a Common Biomechanism Underlying Metal Toxicity.- 6 Neurotoxic Metals and Neuronal Signalling Processes.- 7 Cognitive, Neural, and Behavioral Effects of Low-Level Lead Exposure.- 8 Lead Poisoning, Toxocariasis, and Pica: Links to Neurobehavioral Disorders.- 9 Nocardia: An Environmental Bacterium Possibly Associated with Neurodegenerative Diseases in Humans.- II. Toxicants.- 10 Neurotoxicity of Polychlorinated Biphenyls: The Role of Ortho-Substituted Congeners in Altering Neurochemical Function.- 11 Central Nervous System Plasticity and Pathology Induced by Exposure to Organophosphate Pesticides.- 12 Silver Impregnation of Organophosphorus-Induced Delayed Neuropathy in the Central Nervous System.- 13 Neuroreceptor and Behavioral Effects of DDT and Pyrethroids in Immature and Adult Mammals.- III. Selected Mechanisms of Action.- 14 Formation of Excess Reactive Oxygen Species within the Brain.- 15 Acute and Chronic Neurodegenerative Disorders Produced by Dietary Excitotoxins.- 16 Behavioral and Neuropathological Consequences of Chronic Exposure to Low Doses of the Dopaminergic Neurotoxin MPTP.- IV. Legal Issues.- 17 Courts, Agencies, and Social Risk Assessment.- Epilogue.