American Coatings Association

OSHA Seeks Comment on Guidance: Applying the “Weight of the Evidence” Approach for Dealing with Complex Scientific Studies when Classifying Products under HCS 2012


On Feb. 16, the U.S. Occupational Safety and Health Administration (OSHA) released new guidance on how to apply the “weight of the evidence” (WoE) approach when dealing with complex scientific studies and classifying chemicals and mixtures under HCS 2012. OSHA is accepting comments on this guidance during a brief 45-day comment period, until March 31. According to OSHA, the guidance is intended to help employers consider all available information when classifying hazardous chemicals. The guidance is also intended to help educate chemical manufacturers and importers about OSHA’s expectations on how to prepare accurate safety data sheets (SDS) and labels required to protect worker safety.

According to OSHA’s press release, the “weight of evidence” approach assists manufacturers, importers and employers to evaluate scientific studies on the potential health hazards of a chemical and determine the Hazard Communication Standard (HCS 2012) classification. The HCS 2012 classification then informs manufacturers what information must be disclosed on the label and SDS for compliance with the HCS 2012. This draft is a companion document to a recently posted Hazard Classification Guidance.

Under OHSA’s HCS, as outlined in the guidance, 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 document aims to help the label and SDS preparer apply the “weight of evidence” approach when dealing with complex scientific studies. The guidance is not a final regulation or proposed regulation, but according to OSHA, is “advisory” in nature and should be used to clarify compliance requirements.

In particular, OSHA is interested in receiving comments on the guidance in response to its following questions:

  1. OSHA’s primary goal in the draft WoE guidance is to provide classifiers with an overview on how to approach a weight of evidence evaluation using the criteria that was adopted under the Hazard Communication Standard (29 CFR 1910.1200). Has OSHA achieved this goal?
  2. OSHA intended to write this draft guidance in language that is appropriate for, and easily understood by, personnel who would be primarily responsible for the classification process. Has OSHA achieved this objective?
  3. OSHA has also provided guidance on how to use other authoritative bodies that use a weight of evidence or systematic approach. Is this type of guidance helpful? Are there other authoritative bodies that OSHA should reference that that provide weight of evidence evaluations that would be relevant to worker exposures?
  4. To simplify the guidance OSHA has primarily focused on chronic hazards: Carcinogens, germ cell mutagens and reproductive toxicants since these are more complex endpoints and generally need a higher degree of expert judgement to interpret studies. Did OSHA adequately identify the key considerations for a WoE evaluation of these toxicants? Was the OSHA discussion of the WoE approach appropriate for this guidance document?
  5. OSHA has provided a section on classification based on a single positive study. Was this section useful?
  6. OSHA has provided a series of examples to demonstrate the principles discussed in the WoE guidance document. Are these examples helpful? How can they be improved?

ACA members are encouraged to read the guidance and notify ACA if they have any concerns or questions before the comment period closes.

Contact ACA’s Javaneh Nekoomaram or Stephen Wieroniey for more information.