Listing of decomposition products on MSDSs where they are present during normal use or only in the event of a fire.

Standard Number: 1910.1200(g)

February 17, 1989

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.