A Guide to OSHA’s Proposed Updates to the Hazard Communication Standard

The Occupational Safety and Health Administration’s (OSHA’s) Hazard Communication Standard (HCS) is set to change soon. The HCS changes are still under review, but they’re expected to become law sometime in 2024.

What’s changing?

OSHA proposed its latest round of changes to the HCS in 2021. These changes are meant to keep pace with the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). The GHS standardizes how chemical manufacturers, importers and distributors classify chemical hazards and communicates those hazards so everyone can understand them. Harmonized classification and labeling are essential in a global supply chain.

The last time OSHA updated the HCS was in 2012.

OSHA’s proposed changes affect the entire HCS. They include significant changes to the appendices, from definitions to chemical classifications to health and physical hazards. Many changes relate to how chemicals are evaluated and classified. This is something chemical manufacturers, importers and distributors do.

Even if your business doesn’t evaluate chemicals, you should familiarize yourself with these revisions. Changes to how a chemical is classified also affect its label, safety data sheet (SDS) information and pictogram. You’ll need to educate your employees on these changes.

The following summarizes key changes in OSHA’s “Proposed Rulemaking to Amend the Hazard Communication Standard.”

Changes to definitions

OSHA has proposed changes to the definitions in subsection 1910.1200(c). They include the following:

Definitions in 1910.1200(c)	Text of the definition
Bulk shipment	A bulk shipment is any hazardous chemical transported where the mode of transportation (vehicle) is the immediate container (e.g., a tanker truck, rail car or intermodal container).
Combustible dust	Combustible dust is finely divided solid particles of a substance or mixture liable to catch fire or explode on ignition when dispersed in air or other oxidizing media.
Gas	Gas is a substance that has a vapor pressure greater than 43.51 pounds per square inch (psi) or 300 kilopascals (kPa) absolute at 122 F (50 C); or is completely gaseous at 68 F (20 C) at a standard pressure of 14.69 psi (101.3 kPa).
Immediate outer package	An immediate outer package is the first package enclosing the hazardous chemical container.
Liquid	A liquid is a substance or mixture that: Has a vapor pressure of no more than 43.51 psi (300 kPa (3 bar)) at 122 F (50 C) Is not completely gaseous at 68 F (20 C) and at a standard pressure of 101.3 kPa Has a melting point or initial melting point of 68 F (20 C) or less at a standard pressure of 14.69 psi (101.3 kPa) A viscous substance or mixture for which a melting point cannot be determined shall be subjected to one of the following tests, incorporated by reference in 1910.6: A test of whether the material is a liquid or solid using the ASTM D 4359-90 (2019) A penetrometer test for determining fluidity, prescribed in the European Agreement Concerning the International Carriage of Dangerous Goods by Road, section 2.3.4 of Annex A (2019)
Physician or other licensed health care professional (PLHCP)	A PLHCP is an individual whose legally permitted scope of practice (i.e., license, registration or certification) allows them to independently provide or be delegated the responsibility to provide some or all of the health care services referenced in the section on trade secrets, 1910.1200(i).
Pyrophoric gas	OSHA relocated the definition of pyrophoric gas from subsection 1910.1200(c) to Appendix B.2, Flammable Gases. (More on these changes later.)
Released for shipment	A chemical is released for shipment once it has been packaged and labeled in the manner in which it will be distributed or sold.
Solid	A substance or mixture that does not meet the definitions of liquid or gas.

Hazard classification of chemicals

OSHA added text to hazard classification section 1910.1200(d). Chemical manufacturers, importers and distributors are responsible for classifying chemicals. When classifying a chemical, they should consider the hazards that can exist under normal use and in foreseeable emergencies. They should include risks associated with changes to the chemical’s physical form or resulting from a reaction with other chemicals under normal conditions of use.

Labels and other forms of warning

OSHA added text in section 1910.1200(f). A summary of these changes is below:

• Regarding chemical hazards not otherwise classified (HNOC), OSHA added that HNOC and “hazards resulting from a reaction with other chemicals under normal conditions of use” don’t have to be addressed on the container.
• Any chemicals requiring labels, tags or markings must also include the date the chemical was released for shipment.
• When a chemical manufacturer, importer or distributor moves large amounts of dangerous chemicals, the warning label can be put directly on the container or sent electronically or with shipping documents. The idea is that workers receiving the shipment will have immediate access to the warning label in printed form.
• If the Department of Transportation (DOT) already requires a particular pictogram on a shipped container’s label, it should use the DOT’s pictogram, not OSHA’s.

Changes to the trade secrets section

OSHA replaced “percentage of composition” with “concentration or concentration range” throughout. It also replaced “physician or nurse” with “PLHCP.”

Changes to the HCS appendices

OSHA made significant changes to the HCS appendices in this update. The changes are addressed below, broken down by each appendix:

• Appendix A — Health Hazard Criteria (Mandatory)
• Appendix B — Physical Criteria (Mandatory)
• Appendix C — Allocation Of Label Elements (Mandatory)
• Appendix D — Safety Data Sheets (Mandatory)
• Appendix E — Definition Of Trade Secret (Mandatory)
• Appendix F — Guidance For Hazard Classifications Re: Carcinogenicity (Non-Mandatory)

Appendix A — Health Hazard Criteria

Appendix A is a substantial guideline on identifying and characterizing health hazards. It defines chemical health hazards and suggests they can cause the following health problems:

• Acute toxicity (through any route of exposure)
• Skin corrosion or irritation
• Eye damage or irritation
• Respiratory or skin sensitization
• Germ cell mutagenicity
• Carcinogenicity
• Reproductive toxicity
• Target organ toxicity (through single or repeated exposure)
• Aspiration hazard

It also explains how to classify these hazards using recommended or alternative test methods and criteria for mixtures. It offers updated classification systems to reduce animal testing for some chemicals. For example, in the case of classifying inhalation toxicity, OSHA suggests that chemical evaluations consider data gathered from:

• Expert judgment
• Workplace exposures
• Testing done in a tube or dish (in vitro)
• Existing animal testing

The subsections can help you assess and categorize the severity and likelihood of each type of hazard. For example, OSHA lists five hazard categories for acute toxicity, from one (fatal or toxic substances) to five (may be harmful if exposed).

OSHA proposed changes to Appendix A, including the following:

Section	Title	Notable revisions
A.1	Acute toxicity	Changed the definition of “acute toxicity,” removing the time frames required for exposure. Changed the criteria for testing and classifying chemicals to their potential to harm when inhaled. If evidence suggests the chemical or mixture can destroy tissue (aka corrosive), the classifier must evaluate whether it can damage the respiratory tract.
A.1.2	Classification criteria for substances	Expanded this section to include the respiratory tract. If evidence suggests the chemical or mixture can destroy tissue when inhaled, the classifier must evaluate whether it can damage the respiratory tract.
A.2	Skin corrosion/irritation	Changed the definitions of “skin corrosion” and “skin irritation,” removing the time frames required for exposure. Changed section A.2.3 to reflect a tiered approach for classifying substances using other data elements. These changes were also reflected in the corresponding Figure A.2.1. The aim is to organize, evaluate and classify hazards based on available evidence. This helps avoid additional animal tests whenever possible. Added guidance on calculating ingredients for Table A.2.3: Concentration of ingredients of a mixture classified as skin Category 1 or 2 that would trigger classification of the mixture as hazardous to the skin.
A.3	Serious eye damage/Eye irritation	Changed the definitions of “serious eye damage” and “eye irritation,” removing the time frames required for exposure. Added guidance to section A.3.2 on how to classify substances. Clarified the methods for classifying irreversible (Table A.3.1) and reversible (Table A.3.2) eye damage. Changed the tiered methodology for assessing eye damage and eye irritation. Added a definition for “germ cell mutagenicity.” Changed the definition of “carcinogenicity.” Changed the definition of “reproductive toxicity.” Amended the definitions “specific target organ toxicity–single exposure (STOT-SE)” and “specific target organ toxicity–repeated exposure (STOT-RE).” Added the definition of “aspiration hazard.” Added guidance on classifying mixtures when all or some data are available.

Appendix B  — Physical Criteria

Appendix B gives detailed physical criteria for classifying hazardous chemicals. This information is mandatory for all workplaces that handle hazardous materials. It is designed to ensure workers are aware of and adequately protected against workplace hazards.

The section is broken down into three subsections. The subsections explain different aspects of classifying hazardous chemicals based on physical properties:

• Flammable liquids define the various categories of flammable liquids based on flash point and boiling point.
• Gases under pressure distinguish between four categories of gases: compressed gas, liquefied gas, refrigerated liquefied gas and dissolved gas.
• Chemicals under pressure outline the definitions and classification of aerosols, gases and desensitized explosives.

OSHA proposed changes to Appendix B, including:

Section	Title	Notable revisions
B.1	Explosives	Added two notes under section B.1.3, “additional classification considerations,” including a reference to desensitized explosives.
B.2	Flammable gases	Added definitions and categorizations of “pyrophoric gas” and “chemically unstable gas.” Added new classification considerations and Category 1B to flammable gases in sections B.2.2 and B.2.3.
B.3	Aerosols	Classified aerosols into three categories, depending on their flammability and combustion properties. Changed the phrase from “flammable aerosol” to “aerosol” throughout the section. Added a third category for classifying aerosols to Table B.3.1. Removed aerosols from the scope of flammable gases, gases under pressure, flammable liquids and flammable solids.
B.11	Self-heating chemicals	Added a note about classifying solid chemicals under Table B.11.1.
B.14	Oxidizing solids	Added a test method to section B.14.2 for classifying oxidizing solids.
B.17	Desensitized explosives	Added a chapter on desensitized explosives.

Appendix C — Allocation Of Label Elements

Appendix C provides instructions on assigning appropriate label elements to hazardous products, including the following:

• Allocation procedure. This section outlines the elements of labels that chemical manufacturers, importers and distributors must follow.
• Signal words. You can use only one signal word per label: “danger” and “warning.” Danger is for the most severe threat. Warning is for less severe hazards.
• Hazard statements. Hazard statements describe the nature and degree of a chemical’s hazard. A specific statement is assigned to the chemical depending on its hazard class and category.
• Pictograms. Pictograms are a symbol inside a diamond with a red border. They convey certain health, physical and environmental information. OSHA has created pictograms for specific chemical hazards.
• Precautionary statements. Precautionary statements recommend measures to minimize or prevent adverse effects from exposure, improper storage or handling of hazardous products.
• Precedence of label elements. If there isn’t enough space on a label to include all the relevant signal words, pictograms and hazard statements, this section says what to include and in what order.

OSHA proposed changes to Appendix C, including:

Section	Title	Notable revisions
C.2.3	Hazard symbols and classes	Added “desensitized explosives” to the flame pictogram. Added “hazard not otherwise classified” or the letters “HNOC” to the exclamation below the pictogram. Determined pictograms can only appear once on a label.
C.2.4	Precautionary statement text	Clarified the section on precautionary statements, including substances or mixtures with multiple hazards triggering multiple statements. Labels only need to include one precautionary statement reflecting the highest level and most urgent response. Added the use of “if” statements to clarify multiple precautionary statements concerning medical responses.
C.4	Requirements for signal words, hazard statements, pictograms and precautionary statements	Updated information for each hazard category concerning each pictogram, including desensitized explosives.

Appendix D — Safety Data Sheets

Appendix D outlines the 16 sections an SDS must contain. OSHA proposed changes to Appendix D, including:

Section	Title	Notable revisions
Table D.1	Minimum information for an SDS	Section 9: Changed the terms that should be included in an SDS to describe the chemical’s physical and chemical properties, such as particle size. Section 11: Added a requirement for the SDS preparer to list known chemical interactions. If they use alternative methods, they must show them. For example, they might use information from a similar group of chemicals instead of the exact one to determine its potential harm to health.

Appendix E  — Definition Of Trade Secret

Appendix E sets guidelines for handling proprietary information about chemical compilations considered business trade secrets.

A trade secret could be a formula, pattern, device or compilation a business uses and keeps confidential to give it an advantage over its competitors. Companies may not want to disclose the chemical formula for their product on a label or an SDS. They’d need to get permission from OSHA. This section details ways to handle trade secrets, including disclosing them for evaluation.

OSHA did not change Appendix E.

Appendix F  — Guidance For Hazard Classifications Re: Carcinogenicity

Appendix F is not mandatory and only provides additional guidance on carcinogenicity. The required criteria for classifying a chemical’s carcinogenicity appear in Appendix A.6 of the HCS.

OSHA did not change Appendix F.

Effective dates for the 2024 proposed changes

The 2024 proposed rule removes most of the 2012 HCS text and dates, replacing them with the following compliance dates for the new rules:

• The HSC section revisions take effect 60 days after the date the final rule is published. (It was still pending at the time of this writing.)
• Chemical manufacturers, importers and distributors evaluating substances have one year after the final rule’s effective date to update their evaluation standards, labels and SDSs.
• Chemical manufacturers, importers and distributors evaluating mixtures have two years after the effective date of the final rule to update their evaluation standards, labels and SDSs.

OSHA’s proposed changes will revise the HCS, impacting how chemical hazards are classified and conveyed through labeling. Over the next two years, chemical manufacturers, importers and distributors will adapt to chemical labels and SDS changes. Some chemical manufacturers will be quicker than others to adapt. Be on the lookout once the changes go into effect.

Review your training and hazard communication program

OSHA requires employers to have a current written hazard communication program. Your hazard communication program should include a chemical inventory and documented employee training.

Train your employees on chemical hazards, safety measures, SDSs, pictograms and labels. Ensure they know where your SDSs and chemical lists are stored. Retrain employees before using new chemicals or when chemicals are reclassified. Ask the chemical manufacturer or supplier to highlight changes on the SDSs for your workplace chemicals. If you use SDS management software, ask your account manager for guidance on updates.

You’ll be ahead of the curve and ready to revise your programs if the HCS changes affect your operations.