The Dictionary of Hazardous Substances lists 329 materials and describes pertinent data under the headings of general properties, toxicity and detection. The Manual is a field handbook for officials who are responsible for damage assessment after a spill of oil or hazardous polluting substances. It gives procedures and checklists for on-site use, with a dictionary of data about hazardous substances. The Manual is to be used before a field investigation, as a reminder of what will have to be done; during the investigation, as a guide to techniques and step-by-step procedures; and when reporting, as a check-list on completeness. The Manual refers to standard methods for detection and identification of a spill and for measurement of damage and gives rules for selection of sampling stations and schedules. A systematic method is recommended for applying the field data to quantitative damage assessment. To guide the investigation and reporting, sections of the Manual deal with statistical requirements, layman's rules for meeting legal requirements, and a check-list of details that should be in a full damage assessment report.