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OSHA Hazard Communication Letters of Interpretation
Acute Toxicity classification under hazard communication
- Issued
- Record type
- Interpretation
- Historical HazCom standard
- HCS 2012
- Current HazCom standard
- HCS 2024, as amended
ILPI assessment: Evidence-based principles retained; use current criteria and renumbered provision
Its main HazCom principles remain useful: omitted precautionary statements need a reasoned evidence basis, and mixture classification must use available data and the applicable tiered criteria. An absence of classification due to missing data is not a finding that the mixture is harmless. This letter interprets HCS 2012.
Under the current HCS, the omission provision is C.2.4.9, rather than the quoted former C.2.4.8. Apply general classification considerations, acute-toxicity criteria, and unknown-acute-toxicity labeling with SDS hazard information. Assess each relevant route and all other hazard classes; do not infer that lack of acute data excuses evaluation of the available evidence.
Last reviewed: .
About this ILPI assessment
This comparison with current requirements is not a finding that OSHA has formally withdrawn this letter. This assessment reflects editorial judgment informed by human review and AI assistance. It is an opinion, may contain errors or omissions, and is not an official OSHA determination. For guidance on how OSHA requirements apply to your circumstances, contact your local OSHA office.
OSHA's notice about interpretation letters
The following notice is published on OSHA's interpretation pages; it is general guidance, not a letter-specific withdrawal notice.
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.
Source: OSHA's original letter page.
April 15, 2014
David Cawthon, Ph.D.
Center for Toxicology and Environmental Health, LLC
5120 North Shore Drive
North Little Rock, AR 72118
Dear Dr. Cawthon:
Thank you for your October 14, 2013, letter to the Occupational Safety and Health Administration's (OSHA) Directorate of Enforcement Programs. Your question concerns classification and labeling requirements under the Hazard Communication standard, 29 CFR 1910.1200 [ILPI: Original HCS 2012 context · Current HCS], which was revised March 26, 2012 (HCS 2012). 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.
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Question 1: In the HCS 2012, Appendix C, Allocation of Label Elements, C.2.4.8 [ILPI: Original HCS 2012 context · Current HCS; renumbered from C.2.4.8 to C.2.4.9] states, "If the chemical manufacturer, importer or responsible party can demonstrate that a precautionary statement is inappropriate to a specific substance or mixture, the precautionary statement may be omitted from the label." What specifically needs to be done to "demonstrate" a precautionary statement is inappropriate? For example, how would one demonstrate that the precautionary statement, "Store locked up" is not appropriate for a wall board joint compound, which contains crystalline silica, a known carcinogen?
[ILPI note: Original HCS 2012 context · Current HCS. Demonstrable inappropriateness is not a general permission to delete precautionary statements without evidence.]
Response: Paragraph (f)(1)(v) [ILPI: Original HCS 2012 context · Current HCS] of HCS 2012 requires labels of shipped containers of hazardous chemicals to include, among other label elements, the precautionary statements appropriate for the chemical's hazards, as delineated in Appendix C. Under Appendix C.4.9 [ILPI: Original HCS 2012 context · Current HCS], a chemical that is a carcinogen must include the precautionary statement "Store locked up." In some cases, however, the precautionary statement, "store locked up," may not be appropriate for a particular chemical. If the manufacturer, importer or responsible party can document that the chemical will never present the hazard during storage, but only during use or processing, this precautionary statement may be omitted. If the downstream user has a question about the presence or absence of a precautionary statement, he or she should contact the manufacturer for further information.
The manufacturer, importer or responsible party must have reasonable information, studies or data to support its position that a precautionary statement is inappropriate. The data must meet the criteria in the HCS, Appendix A, Health Hazard Criteria, chapter A.0 [ILPI: Original HCS 2012 context · Current HCS]. It is not acceptable for a manufacturer, importer or responsible party to omit a precautionary statement without data or based only on anecdotal evidence.
Question 2: HCS 2012 Appendix A, Health Hazard Criteria, A.1.3.6.2.3 [ILPI: Original HCS 2012 context · Current HCS] states, in pertinent part, "Where an ingredient with unknown acute toxicity is used in a mixture at a concentration ≥ 1%, and the mixture is not classified based on testing of the mixture as a whole, a statement that X% of the mixture consists of ingredient(s) of unknown acute toxicity is required on the label and safety data sheet in such cases ..." What specific evidence is necessary to make a determination that a mixture does not need to be classified for acute toxicity when no actual data is available for the ingredients or the mixture as a whole?
Response: When classifying a product, manufacturers, importers or responsible parties must comply with all the information in both Appendices A and B of HCS 2012. Specifically, the classification should start with chapter A.0 [ILPI: Original HCS 2012 context · Current HCS], General Classification Considerations, as this chapter provides guidance on the appropriate data to use in determining a product's classification. In A.0.2 [ILPI: Original HCS 2012 context · Current HCS], Available Data, Test Methods and Test Data Quality, A.0.2.3 [ILPI: Original HCS 2012 context · Current HCS] defines the term "scientifically validated" as it relates to data used in classification. In addition, A.0.2.5 [ILPI: Original HCS 2012 context · Current HCS] and A.0.2.6 [ILPI: Original HCS 2012 context · Current HCS] discuss the type of data used and the use of epidemiological data and experience. In A.0.3 [ILPI: Original HCS 2012 context · Current HCS], Classification Based on Weight of Evidence, A.0.3.2 [ILPI: Original HCS 2012 context · Current HCS] discusses evaluating the quality and consistency of the data. In A.0.4 [ILPI: Original HCS 2012 context · Current HCS], Considerations for the Classification of Mixtures, A.0.4.1(c) [ILPI: Original HCS 2012 context · Current HCS; subparagraph (c) in the linked paragraph] discusses what to do if testing data is not available for the mixture and the bridging principles cannot be applied: "...the method(s) described in each chapter for estimating the hazards based on the information known will be applied to classify the mixture (e.g., application of cut-off values/concentration limits)." Please note, as stated in A.0.2.1 [ILPI: Original HCS 2012 context · Current HCS], there is no requirement to test a product.
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The approach for classifying mixtures for acute toxicity is tiered, and where the mixture has been tested to determine its acute toxicity, it is classified according to the criteria provided in Table A.1.1 [ILPI: Original HCS 2012 context · Current HCS]. See A.1.3.4 [ILPI: Original HCS 2012 context · Current HCS]. If there is no acute toxicity data for the mixture, A.1.3.5 [ILPI: Original HCS 2012 context · Current HCS] requires that classification be based on bridging principles. If bridging principles cannot be applied, classification is based on the ingredients of the mixture. See A.1.3.6 [ILPI: Original HCS 2012 context · Current HCS]. If there is no acute toxicity data for the mixture as a whole, bridging principles cannot be applied, and there is no acute toxicity data for the individual ingredients, the mixture does not need to be classified as an acute toxicant and it is not necessary to indicate that there is an ingredient with unknown acute toxicity. As explained in the preamble to HCS 2012, the requirement in A.1.3.6.2.3 [ILPI: Original HCS 2012 context · Current HCS] to include the percent of the mixture that contains one or more ingredients of unknown acute toxicity only applies where there are other ingredients known to be acutely toxic in the mixture. 77 FR 17574, 17738 ("[W]here there is one or more ingredient of unknown toxicity in a mixture of other ingredients known to be acutely toxic, the calculation for predicting the acute toxicity cannot be completely accurate. Therefore, as suggested in the GHS, OSHA has indicated that a statement must be on the label and SDS indicating that a percentage of the mixture has unknown acute toxicity.").
[ILPI note: Original HCS 2012 context · Current HCS. This is a narrow no-data scenario, not evidence of safety. Apply current acute-toxicity criteria and unknown-toxicity statements, considering routes, known ingredients and all relevant information.]
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 https://www.osha.gov. If you have further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.
Sincerely,
Thomas Galassi, Director
Directorate of Enforcement Programs
The original official public domain version of this document is available from OSHA at https://www.osha.gov/laws-regs/standardinterpretations/2014-04-15-0.