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Hazardous Chemicals: OSHA Offers Weight-of-Evidence Guidance

Feb. 23, 2016
Document aims to assist manufacturers evaluating hazardous chemicals

On February 16, 2016, the U.S. Occupational Safety and Health Administration (OSHA) released for public comment its “Guidance on Data Evaluation for Weight of Evidence Determination.” The document aims to help employers consider all available information when classifying hazardous chemicals for labeling and safety data sheet (SDS) completion purposes. Because of the critical importance of satisfying these regulatory obligations correctly, understanding the Guidance is essential.



As part of OSHA’s efforts to protect workers from the potential hazards chemicals may pose, the agency plans to issue new guidance on how to apply the weight-of-evidence approach when dealing with scientific studies. According to OSHA, the approach assists manufacturers, importers and employers in evaluating scientific studies on a chemical substance with a view toward assessing the chemical’s potential health hazards and determining what information must be disclosed on the label and in the SDS in compliance with the Hazard Communication Standard (HCS). The Guidance is a companion document to a recently posted Hazard Classification Guidance, on which OSHA is not accepting comment.

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Regulatory changes necessitated the need for new guidance. In March 2012, OSHA aligned the HCS with the U.N. Globally Harmonized System of Classification and Labeling of Chemicals (GHS) (For details on GHS, see: “Prepare for the GHS Compliance Deadline”). The GHS expressly allows criteria that include the use of a weight-of-evidence approach when evaluating the health hazards of a chemical. Under the HCS, chemical manufacturers and importers must review all available scientific evidence concerning the physical and health hazards of the chemicals they produce or import to determine if they are hazardous.

This evaluation is required under several provisions of the HCS. First, chemical manufacturers and importers must evaluate the hazards of chemicals they produce or import under 29 C.F.R. § 1910.1200(d). Second, for chemicals found to be hazardous, the manufacturer or importer must prepare an SDS and container labels must be transmitted to downstream users of the chemicals. Employers also must maintain an SDS in the workplace for each hazardous chemical they use (29 C.F.R. § 1910.1200(f) and (g)). Finally, all employers must develop a written hazard communication program and provide information and training to workers about the hazardous chemicals in their workplace (29 C.F.R. § 1910.1200(e) and (f)).

Given the introduction of a weight-of-evidence approach in determining health hazards that must be disclosed on a product’s label and SDS, OSHA properly recognized that guidance on how to conduct a systematic application of this approach was needed. The Guidance sets forth the elements of such an approach that, in OSHA’s view, is consistent with the GHS criteria and explains the various types of information that must be considered to establish classification under the HCS. The Guidance aims to help the label and SDS preparer apply the weight-of-evidence approach when dealing with complex scientific studies.

OSHA notes the Guidance isn’t a standard or regulation, doesn’t create any new legal obligations, and is intended to assist employers in providing a safe and healthful workplace. The recommendations are advisory in nature, informational in content, and intended to educate scientists and non-scientists alike who prepare labels and SDSs so that they provide accurate and consistent information.


This is important guidance and a weight-of-evidence approach is essential to evaluating hazardous chemicals. Stakeholders will appreciate that in the past, if a single positive study on a chemical was identified, OSHA could permissibly rely on this single study for classification and labeling purposes. In light of HCS 2012, a weight-of-evidence approach can take a more systematic assessment of possible hazards relying upon a careful review of all available pertinent data and information. This is good news, so a careful review of the Guidance is recommended.

OSHA will accept comments until March 31, 2016. The document is detailed; stakeholders may request more time to review and comment on this important document.

LYNN BERGESON is Chemical Processing's Regulatory Editor. You can e-mail her at [email protected]Lynn is managing director of Bergeson & Campbell, P.C., a Washington, D.C.-based law firm that concentrates on conventional, biobased, and nanoscale chemical industry issues. She served as chair of the American Bar Association Section of Environment, Energy, and Resources (2005-2006).

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