GHS vs OSHA HCS 2024: What Changed for US Chemical Labelling
In May 2024, OSHA finalised its update to the Hazard Communication Standard (HCS), aligning US requirements with GHS Revision 7. For EHS professionals, chemical manufacturers, and importers, this update introduces significant changes to how chemicals are classified, labelled, and communicated.
Background: HCS 2012 vs HCS 2024
OSHA first aligned HCS with GHS in 2012 (HCS 2012), which adopted GHS Rev.3. The 2024 update advances alignment to GHS Rev.7, bringing the US closer to international and EU (CLP) standards — though not identical.
Key Changes in HCS 2024
1. New and Revised Hazard Classes
HCS 2024 adds several hazard classes not covered in HCS 2012:
| New/Revised Hazard Class | What Changed |
|---|---|
| Flammable gases | Added categories for chemically unstable gases and non-flammable aerosols |
| Desensitised explosives | New hazard class added |
| Non-flammable aerosols | Separated from flammable aerosols |
| Reproductive toxicity | Added new sub-category for effects on lactation |
| Respiratory sensitisation | Added Category 1A and 1B sub-categories |
| Skin sensitisation | Added Category 1A and 1B sub-categories |
2. Updated Label Requirements
Small container labels: HCS 2024 introduces alternative labelling provisions for containers ≤ 100 mL, allowing certain label elements to be placed on pull-out labels, fold-back labels, or tags.
Concentration ranges: Manufacturers may use concentration ranges instead of exact concentrations in Section 3 of the SDS when exact percentages are trade secrets — with tighter ranges than previously allowed.
Bulk shipment labels: Updated requirements for labels on bulk containers and vessels.
3. Revised SDS Requirements
HCS 2024 updates Section 2 (Hazard Identification) and Section 9 (Physical and Chemical Properties) of the SDS format:
- Section 9 now requires additional physical properties including particle size, dust explosion classification, and flammability limits
- Particle characteristics relevant to inhalation hazards must be reported
4. Aerosol Classification Changes
Aerosols are now classified into three categories:
- Flammable aerosol (Category 1 and 2)
- Non-flammable aerosol (Category 3) — new in HCS 2024
- Separate classification criteria based on heat of combustion and chemical composition
Compliance Deadlines
| Requirement | Deadline |
|---|---|
| Chemical manufacturers and importers update SDSs | January 19, 2026 |
| Chemical manufacturers and importers update labels | July 19, 2026 |
| Distributors can ship with old labels | January 19, 2027 |
| Employers update workplace labels and training | July 19, 2027 |
Source: OSHA Final Rule, Federal Register Vol. 89, May 2024
What Stays the Same
The core structure of GHS communication remains unchanged:
- 16-section SDS format
- 9 GHS pictograms (GHS01–GHS09)
- Two signal words (Danger / Warning)
- H-statements and P-statements system
- Requirement for SDS in English (additional languages optional)
HCS 2024 vs CLP (EU): Still Not Identical
Despite both being based on GHS, OSHA HCS and EU CLP differ in important ways:
| Aspect | OSHA HCS 2024 | EU CLP |
|---|---|---|
| GHS revision basis | Rev.7 | Rev.10 (partially) |
| Harmonised classifications | Manufacturer determines | ECHA Annex VI mandatory |
| SDS language | English | All official EU languages |
| Label size requirements | Performance-based | Specific minimum sizes in Annex I |
| M-factors | Not required | Required for aquatic toxicity |
What EHS Professionals Should Do Now
- Audit existing SDSs — identify which documents need updating for new hazard classes
- Check aerosol products — reclassify under new aerosol categories if applicable
- Update respiratory and skin sensitiser classifications — new 1A/1B sub-categories may apply
- Revise label templates — especially for small containers and bulk shipments
- Update employee training — by the July 2027 deadline
Related Resources
- GHS Signal Words: Danger vs Warning — how signal words work under HCS 2024
- GHS H-Statements Complete Guide — updated H-codes under GHS Rev.7
- GHS P-Statements Guide — precautionary statements in HCS 2024 format
- GHS Hazard Symbols and Meanings — pictogram requirements under HCS 2024
Reference: OSHA HCS 2024 Final Rule, 29 CFR 1910.1200 (May 2024). UN GHS Rev.7. CLP Regulation (EC) No 1272/2008 as amended.