Silica bound in rubber under hazard communication

February 8, 1989

Mr. D. A. Polsinelli
Product Regulatory Specialist
Product Regulatory Operation
Silcone Products
Division General Electric Company
[Recipient address omitted]
Dear Mr. Polsinelli:

This is in response to your letter of August 22, 1988, concerning coverage of hazardous chemicals physically bound in a material under the Hazard Communication Standard (HCS) 29 CFR 1910.1200. Please accept my apology for the delay in response.

Your specific question concerned whether crystalline silica, when bound in a polymeric compound and silicone rubber elastomers used to fabricate rubber articles, is covered by the HCS. If a hazardous chemical is present in a mixture in reportable quantities (i.e., 0.1 percent for carcinogens and 1.0 percent for other health hazards), it is covered by the standard unless the mixture has been tested as a whole or the material is bound in such a way that employees can not be exposed.

The standard defines exposure as including potential as well as measurable exposure, and 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. If there is no exposure either under normal conditions of use or in a foreseeable emergency, then the chemical is not covered by the standard. However, if under normal conditions of use an action, such a cutting or grinding, is performed on the product that could release the crystalline silica, then the product would be covered by the HCS and the presence of silica must be indicated on the material safety data sheet.

We hope this information is helpful to you. Please feel free to contact us again if further assistance is needed.

Sincerely,
Thomas J. Shepich, Director
Directorate of Compliance Programs