In the Hazard Communication Standard (HCS), the Occupational Safety and Health Administration (OSHA) chose labels, Material Safety Data Sheets (MSDSs), and training as the vehicles for conveying to workers information about hazards on the job. Labels have always been aimed at the worker. MSDSs, on the other hand, have been written largely for health professionals. Training should, therefore, include the meaning of technical terms in labels and MSDSs so that workers can understand them.

A label is intended to provide an immediate warning about hazardous materials in the workplace. It may be in written or graphic form and must be tied in with training and MSDSs. The label must include the identity of the hazardous chemicals and appropriate warnings about the hazards. The label format is optional, and existing systems may be used. Some alternatives to labeling are allowed, such as large posters describing contents and hazards of a series of similar reactors. Chemical manufacturers, importers, and distributors must also include the name and address of the manufacturer of materials being shipped out of a plant. Substances covered by other federal laws are exempt from HCS's shipped container labeling requirements.

MSDSs complement the label and are more complex. They include: (1) the identity used on the label (except trade secrets) and the specific chemical identity of the hazardous ingredients; (2) physical and chemical characteristics of hazardous materials; (3) fire, explosion, and reactivity hazards; (4) health hazards—both short- and long-term; (5) safe handling and use procedures; (6) emergency and first aid procedures; and (7) date and name of the responsible party preparing the MSDS.

The Hazard Communication standard requires chemical manufacturers to make MSDSs available to their employees. It also requires them to supply MSDSs to downstream manufacturing employers, who in turn must make them available to employees. Clearly then, the chemical manufacturers face the challenge of preparing complete MSDSs. Manufacturing employers must be sure that their workers do indeed get the message.