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• Standard Number: 1910.1450

U.S. Department of Labor
Occupational Safety and Health Administration
Washington, D.C. 20210

Reply to the Attention of:

JUL 5 1990 

MEMORANDUM FOR:     DAVID M. SMITH, Director
                   Office of Health Compliance Assistance

FROM:               SHELDON WEINER, Director
                   Office of Standards Analysis and Promulgation

SUBJECT:            Interpretation of Substances With High Acute Toxicity as
                   Used in the Occupational Exposures to Hazardous 
                   Chemicals in the Laboratory Standard
Helen Li, Industrial Hygienist, has requested the following interpretation.

Although there is a basic difference between the Hazard Communication Standard and the Occupational Exposures to Hazardous Chemicals in the Laboratory Standard, the laboratory standard strives to be consistent with Hazard Communication Standard definitions.

The Hazard Communication Standard (HCS) delineates between "acute" and "chronic" on the basis of severity or duration of effects and states, "acute effects usually occur rapidly as a result of short-term exposures, and are of short duration." The HCS also defines explicitly the terms "highly toxic" and "toxic" as they relate to chemicals. The preamble discussion of the Chemical Hygiene Plan describes substances with "high acute toxicity" as highly toxic noncarcinogenic materials or highly volatile toxic materials such as hydrogen cyanide, hydrogen sulfide and nitrogen dioxide. The preamble also states that such substances may be fatal or cause damage to target organs as a result of a single exposure or exposures of short duration.

Therefore, the laboratory standard requirements for substances with "high acute toxicity" must include those substances defined in the HCS as highly toxic or toxic which may be fatal or cause damage to target organs as a result of a single exposure or exposures of short duration.

If there are any further questions regarding this issue, please contact Jennifer Courtney at 523-7166.

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