A small piece published on the New York Times website.  Useful for beginners in the US:

The U.S. Occupational Safety and Health Administration (OSHA) requires that business owners maintain a Material Safety Data Sheet (MSDS) for every potentially hazardous material their employees come in contact with during the course of their daily business activities. These documents provide information such as melting and boiling points for hazardous materials, toxicity levels, possible health effects of exposure, first aid procedures, storage and disposal advice, and spill and leak procedures.

An MSDS protects both you and your employees and also keeps you in compliance with government regulations. You can be penalized for noncompliance.