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.

September 25, 1991

William B. Bunn, III, M.D., J.D., M.P.H.
Senior Director
Health, Safety & Environment
Manville Sales Corporation
Post Office Box 5108
Denver, Colorado 80217-5108

Dear Dr. Bunn:

Thank you for your letters of March 18 and August 19, regarding interpretation and application of the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS), 29 CFR 1910.1200. We apologize for the long delay of this response. You specifically requested that we confirm three interpretations of the HCS; the following statements have been restated from your most recent request of August 19:

"1. If a hazardous material, crystalline silica in this situation, is present in the finished product at greater than the HCS-listed thresholds of 0.1% for suspected or known carcinogens, or 1% for other hazardous ingredients, and if the potential exists for exposure, appropriate MSDSs and labels must be prepared to communicate the hazard. (e.g. the product used contains >O.l% crystalline silica and is in a form which will release dust (powder) when handled, or will be cut or fabricated releasing dust.)"

Assuming that when you refer to a "finished product," you mean something like a roofing shingle, the correct interpretation is related to the definition of "article" and is described as follows:

If a hazardous material such as crystalline silica is present in a finished product, and if, under normal conditions of use, an employee could be exposed to more than very small quantities of that material, appropriate material safety data sheets and labels must be prepared and utilized to communicate the hazard. If the release is a very small quantity, but it still poses a physical hazard or health risk to workers, data sheets and labels must be prepared and utilized.

The percentage cut-offs you referred to are in the hazard determination provisions of the rule. The hazard determination provisions are only applied to the release, or the chemical(s) employees are actually or potentially exposed to under normal conditions of use. For more complete explanation of this interpretation, please see the notice of proposed rulemaking (NPRM) published on August 8, 1988, pp. 29833 through 29898 (copy enclosed.)

"2. Any assessment of risk which may arise as a result of actual, measurable exposure must be separately evaluated by the end user and minimized through their development of suitable engineering or work practice controls for their situation."

This is a correct interpretation of the intent of the rule. OSHA's recently-revised Compliance Instruction for the HCS, CPL 2-2.38C, provides a similar discussion which addresses both issues raised by you in your letter. The language appears in the directive as part of a discussion (Appendix A, page A-21) of a chemical manufacturer's labeling requirements under the rule, but the idea expressed is central to the intent of the HCS:

"Exposure calculations are not permitted in determining whether a hazard must appear on a label. If there is potential for an exposure other than in minute, trace or very small quantities, the hazard must be included when substantiated as required by the HCS. Suppliers may not exclude hazards based on presumed levels of exposure downstream (i.e., omitting a carcinogenic hazard warning because, in the supplier's estimate, presumed exposures will not be high enough to cause the effect). The hazard is an intrinsic property of the chemical. Exposure determines degree of risk and should be addressed in training programs by the downstream employer." (Emphasis added.)

"3. A product containing crystalline silica classified as an article, such as a tire, a brake shoe or roofing shingle, which does not release crystalline silica during normal handling and use, would not be included in labeling and MSDS provisions."

This is a correct interpretation; however, if the finished products you mention are capable of releasing any other hazardous chemicals other than silica, then those exposures would, of course, have to be considered for labeling and MSDS purposes. "Tires", however, are specifically mentioned in OSHA's compliance directive on Hazard Communication as an example of an item that would be considered an "article" under the HCS.

We appreciate having had the opportunity to meet with you and the other representatives of the Manville Corporation and hope this letter affirms our position on the application of the HCS.


Patricia K. Clark, Director
Directorate of Compliance Programs