An identification system for occupationally hazardous materials is described with recommendations for a standard, basis for the system, scope and objective of the system, and components of the system. The system consists of five parts containing information and instructions for the development of an alert symbol, label statements, and a Material Safety Data Sheet (MSDS). The five parts are: definition of a hazardous material; criteria for determination of degree of hazard; preparation of a MSDS; preparation of a hazard alert symbol; and selection of label statements. Relative toxicity rating and acute toxicity criteria are given for materials with different degrees of hazard. Ratings are also given for the flammability and reactivity of materials.