This statement directs the busy physician to sources of information on the use of limitingexposure guides in the prevention and diagnosis of occupational illness. Basic principles are discussed and reference is made to sources giving detailed information. Limitations refer to appropriate levels of (1) air- or water-borne materials or physical energy in the work place, and of (2) toxic material within the bodies of employees. In each case, generally speaking, the limits refer to environmental concentrations of substances or of physical energy or the internal deposition of substances which it is believed that nearly all workers may tolerate day after day without adverse effect. Exceptions to this general rule are explained in the various publications discussed in this guide. Because individual susceptibility varies, discomfort and aggravation of a preexisting condition or occupational illness may result on occasion from exposure at or even below the guide (threshold) limit.
Derivation of Limits