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OSHA Hazard Communication Letters of Interpretation
Listing of decomposition products on MSDSs where they are present during normal use or only in the event of a fire.
- Issued
- Record type
- Interpretation
- Historical standard
- 1910.1200, 1987 expanded rule (PDF)
- Current standard
- HCS 2024, as amended
ILPI assessment: Normal-use hazards remain; blanket fire-information omission is superseded
This letter addresses the obsolete 1987 version of the Hazard Communication Standard (HCS). Its requirement to consider hazardous products generated during normal use remains useful. However, the broad conclusion that fire-generated decomposition products need not appear on an SDS is not consistent with the current SDS content requirements.
Under the current HCS, Section 5 requires specific chemical hazards including hazardous combustion products, and Section 10 requires hazardous decomposition products. Apply anticipated-use evaluation, hazard classification, and the relevant modern criteria instead of a universal 1%/0.1% shortcut.
The current enforcement discussion still distinguishes accidental-fire exposure from “foreseeable emergency.” That scope distinction does not eliminate the separate SDS fire-hazard and decomposition disclosures. Do not confuse an SDS content duty with a requirement to classify every hypothetical fire product as an ingredient.
Last reviewed: .
About this ILPI assessment
This comparison with current requirements is not a finding that OSHA has formally withdrawn this letter. This assessment reflects editorial judgment informed by human review and AI assistance. It is an opinion, may contain errors or omissions, and is not an official OSHA determination. For guidance on how OSHA requirements apply to your circumstances, contact your local OSHA office.
OSHA's notice about interpretation letters
The following notice is published on OSHA's interpretation pages; it is general guidance, not a letter-specific withdrawal notice.
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 https://www.osha.gov.
Source: OSHA's original letter page.
February 17, 1989
Safety Emporium supplies laboratory fixtures such as valves and faucets.
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:
[ILPI note: For current duties, use classification and SDS fire hazards/decomposition products. The historical 1%/0.1% list is not a universal modern disclosure test.]
- They are present in concentrations of 1 percent or greater (by weight or volume), or
- They are carcinogens and are present in concentrations greater than 0.1 percent (by weight or volume), or
- 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
- 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 chemical 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.
[ILPI note: At issuance: 1910.1200, 1987 expanded rule (PDF). This blanket SDS omission conclusion is superseded by Section 5 hazardous combustion-product information and Section 10 hazardous decomposition products. The accidental-fire/foreseeable-emergency distinction does not remove those SDS duties.]
The original official public domain version of this document is available from OSHA at https://www.osha.gov/laws-regs/standardinterpretations/1989-02-17.