OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

February 17, 1989

MEMORANDUM FOR:  LINDA R. ANKU
                REGIONAL ADMINISTRATOR

ATTENTION:       JIM JOHNSTON
                INDUSTRIAL HYGIENIST

THROUGH:         LEO CAREY, DIRECTOR
                OFFICE OF FIELD PROGRAMS

FROM:            THOMAS J. SHEPICH, DIRECTOR
                DIRECTORATE OF COMPLIANCE PROGRAMS

SUBJECT:         Hazard Communication Interpretation

This is in response to your request for guidance regarding the need to list decomposition products on the material safety data sheet where the decomposition products are present during normal use or only in the event of a fire.

The Hazard Communication Standard (HCS) applies to any chemical which is known to be present in the workplace in such a manner that employees may be exposed under normal conditions of use or in a foreseeable emergency.

Specifically, decomposition products released during normal operations, such as hot wire cutting of plastic, must be reported on the material safety data sheet if they pose a health hazards and:

1. They are present in concentrations of 1 percent or greater (by weight or volume), or

2. They are carcinogens and are present in concentrations greater than 0.1 percent (by weight or volume), or

3. They are present in concentrations of less than those given in Subparagraphs 1 and 2 above; but, nevertheless, present a health hazard to employees at that lower level of concentration, or

4. They are present in concentrations of less than those given in the Subparagraphs 1 and 2 above, but on release could exceed an OSHA PEL or ACGIH TLV.

Decomposition products of chemicals exposed to a fire, where exposure to fire is not a normal use of the product, are not covered by the standard and do not have to be listed on the material safety data sheet. In addition, the definition of "foreseeable emergency" does not include employee exposures to hazardous chemicals as a result of a fire.