Exposure limits on blended coating safety sheets

April 15, 2011

Mr. Lance Edwards

National Paint & Coatings Association, Inc.

[Recipient address omitted]

Dear Mr. Edwards:

Thank you for your August 14, 2009, letter to the Occupational Safety and Health Administration's (OSHA's) Directorate of Enforcement Programs concerning your question regarding OSHA's Hazard Communication standard, 29 CFR 1910.1200, regarding the requirements for providing a manufacturer's occupational exposure limit (OEL) on a material safety data sheet (MSDS). We apologize for the delay in responding to your question. This letter constitutes OSHA's interpretation only of the requirements herein, and may not be applicable to any situation not delineated within your original correspondence. Your question and background information have been paraphrased below followed by our reply.

Background: In 2009 the American Conference of Governmental Industrial Hygienists (ACGIH) published a reciprocal calculation procedure (RCP) to use for deriving an OEL for certain refined hydrocarbon solvent (RHS) vapor mixtures. The procedure is provided in Appendix H of the ACGIH Threshold Limit Value and Biological Exposure Indices (TLVs/BEIs) (ACGIH Book). The National Paint & Coatings Association/Federation of Societies for Coating Technology (NPCA/FSCT) is requesting clarification from OSHA on how an RPC-OEL is to be treated on an MSDS.

When a manufacturer produces a paint or coating, the formulation typically includes a mixture of RHSs from various suppliers. Many suppliers provide their solvents with an MSDS that includes an OEL calculated with the RCP method (RCP-OEL). The NPCA/FSCT contends that any RCP-OEL provided on a supplier's MSDS should not be required by OSHA to be used or reproduced on the MSDS prepared by the manufacturer of the coating because the RCP-OEL is not a TLV. Additionally, the NPCA/FSCT feels that while RCP-OELs are useful during the formulation process, once blended with other materials these RCP-OELs for the solvents become meaningless for the end-user. This is because the component RCP-OELs no longer apply to the blended mixture. Furthermore, in most cases the MSDS for a given solvent does not contain adequate information to calculate an RCP-OEL for the final mixture of the blended solvents in the coating or paint.

Question: When a supplier of an RHS provides an RCP-OEL value on their product MSDS, would a paint or coating manufacturer have to include that value on the MSDS for their formulated product, and would they need to calculate a new RCP-OEL for the mixture?

Reply: OSHA's Hazard Communication standard at paragraph 1910.1200(g)(2)(i)(C)(1), requires that manufacturers of any product containing a mixture of hazardous ingredients must include on the product's MSDS certain information about these ingredients. This includes, per paragraph 1910.1200(g)(2)(vi), the "OSHA permissible exposure limit, ACGIH Threshold Limit Value, and any other exposure limit used or recommended by the chemical manufacturer, importer, or employer preparing the material safety data sheet, where available."

OSHA believes that an RCP-OEL provided by the manufacturer of an RHS would be considered a recommended exposure limit for the purpose of 1910.1200(g)(2)(vi). The RCP-OEL may provide additional hazard information to other manufacturers and downstream users when performing risk assessments, exposure monitoring, and developing engineering controls. However, since the RCP is a special use calculation, it can only be applied in situations where certain criteria and limitations are satisfied, as specified in the ACGIH Book. OSHA also understands that it might not be feasible for coating and paint manufacturers to calculate an OEL using the RCP for blends containing these RHS solvents. Finally, OSHA agrees that in many cases once an RHS is blended or mixed into a coating or paint product, the RCP-OEL many no longer be appropriate to list on the MSDS for the coating or paint.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 continue to consult OSHA's website at www.osha.gov. If you have any further questions, please feel free to contact the Office of Health Enforcement at 202-693-2190.

Sincerely,

Thomas Galassi, Director

Directorate of Enforcement Programs