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.

November 4, 1993

Mrs. J. L. Bunyan
Deputy Registration Manager
SafePharm Laboratories Ltd.
Post Office Box No. 45
Derby DEI 2BT

Dear Mrs. Bunyan:

This is a response to your letter of April 21, concerning the requirements under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS), 29 CFR 1910.1200, for hazard evaluation of mixtures containing established mutagens. We will respond to your questions as they were presented in your correspondence.

1. If a mixture contains a known quantity of one or more mutagenic ingredients, is the mixture deemed to be mutagenic, or is further testing required to prove mutagenic potential?

OSHA's Hazard Communication Standard (HCS) (29 CFR 1910.1200) does not specifically address mutagenicity in either the text of the standards final rule (Federal Register, August 24, 1987) or the preamble discussions. It is the agency's position that in vitro tests, independent of other data, do not establish a health hazard as specified under the hazard determination provisions of the standard. Under the HCS the manufacturer does have the responsibility to review all available scientific data when performing a hazard determination for the chemicals they produce. If an in vitro study is the only data available linking a mutagenic response to a chemical exposure, then these studies do not have to be reported on the product's MSDS. Also in terms of testing for mutagenic potential, the HCS does not require testing of chemicals to determine their hazards.

2. Is there a minimum level of a mutagenic ingredient contained in a mixture above which the mixture does not need testing, but can be assumed to be mutagenic?

Please refer to the answer above, the standard does not require testing. For mixtures of hazardous chemicals the HCS requires the following:

If a hazardous chemical is present in the mixture in quantities (i.e., 0.1% for carcinogens, and 1% for other health hazards), it must be reported unless the mixture has been tested as a whole or unless the material is bound in such a way that employees cannot be exposed. If there really is no exposure (and the standard defines exposure as including potential as well as measurable exposure by any route of entry), either under normal conditions of use or in a foreseeable emergency, then the chemical is not covered by the standard, (See Paragraph (b)(2) of 29 CFR 1910.1200). Further, information must also be included on a MSDS for ingredients of a mixture present in concentrations of less than 1% (or 0.1% for carcinogens) when the hazardous substance may be released in a concentration which exceeds an OSHA Permissible Exposure Limit or an American Conference of Governmental Industrial Hygienist's Threshold Limit Value or may present a health risk to exposed employees. An example of the latter may be TDI because it is a sensitizer in very small concentrations, thereby presenting a health risk that must be noted on the MSDS.

We hope this information is helpful. If you have any further questions please contact the Office of Health Compliance Assistance at (202) 219-8036.


Roger A. Clark, Director
Directorate of Compliance Programs