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.

April 2, 2013

Mr. Brian Karlovich
Bayer Material Science
100 Bayer Road
Pittsburg, PA 15205

Dear Mr. Karlovich:

Thank you for your January 22, 2013, letter to the Occupational Safety and Health Administration (OSHA). Your letter was referred to OSHA's Directorate of Enforcement Programs for a response to your specific questions regarding the Hazard Communication standard (HCS 2012), 29 CFR 1910.1200, which is now aligned with the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS). This letter constitutes OSHA's interpretation only of the requirements herein, and may not be applicable to any questions not delineated within your original correspondence. Your paraphrased questions and our responses are below.

Scenario: For classification of acute inhalation toxicity, the European Union allows the use of the split entry concept as discussed in Inhalation Toxicology: Methodological and Regulatory Challenges by Jurgen Pauluhn, published in Experimental Toxicology and Pathology. This concept allows for a modified GHS classification in certain situations. For example, when the aerosol size in the laboratory tests differs from the size expected in the workplace, it leads to the conclusion that there is less risk for workers and therefore a lower classification may be warranted. In this case, if the animal data would result in a category 3 classification, the use of the split entry concept suggests that a category 4 classification may be more appropriate.

Question 1: Does HCS 2012 support the use of the split entry concept?

Response: No. OSHA outlines its classification criteria in Appendices A and B to 29 CFR 1910.1200. We reviewed the article you referenced and found that it did not meet the classification process required by the HCS 2012. The article appears to rely on risk based principles that are not appropriate under OSHA's adoption of the GHS.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at http://www.osha.gov. If you have further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.


Thomas Galassi, Director
Directorate of Enforcement Programs