July 30, 1990

MEMORANDUM FOR: LINDA ANKU

REGIONAL ADMINISTRATOR

FROM: PATRICIA K. CLARK DIRECTOR DESIGNATE DIRECTORATE OF COMPLIANCE PROGRAMS

SUBJECT: Laboratory Standard

This is in response to your memorandum of May 1, requesting interpretation of "high degree of acute toxicity" under the laboratory standard, 29 CFR 1910.1450.

Although there are some basic differences between the Hazard Communication Standard (HCS) and the laboratory standard, the laboratory standard tries to be consistent with HCS definitions. The HCS delineates between "acute" and "chronic" on the basis of severity or duration of effects and states that acute effects usually occur rapidly as a result of short-term exposures and are of short durations. The HCS also defines explicitly the terms "highly toxic" and "toxic" as they relate to chemicals. The preamble discussion of the laboratory standard indicates that substances with high acute toxicity may be fatal or cause damage to target organs as a result of a single exposure or exposure of short duration. Examples given are substances such as hydrogen cyanide, hydrogen sulfide, and nitrogen dioxide.

In other words, substances that are considered to have a high degree of acute toxicity are those substances which are highly toxic or toxic as defined under the HCS and may be fatal or cause damage to target organs as a result of a single exposure or exposures of short duration.

If you need further assistance, please feel free to contact us again.

April 27, 1990

MEMORANDUM FOR: PATRICIA CLARK, Director Designate

FROM: LINDA R. ANKU Regional Administrator

SUBJECT: Laboratory Standard

The new laboratory standard 29 CFR 1910.1450, has requirements for additional employee protection for work with particularly hazardous substances as detailed in section (e)(3)(viii) of the standard. This section states that these particularly hazardous substances include those substances which have a "high degree of acute toxicity." The phrase "high degree of acute toxicity" is undefined in the standard and is subject to wide variation in interpretation. Guidance is requested concerning interpretation of this phrase.

Please contact Jim Johnston of my staff (FTS 596-1201) if you have any questions.