OSHA’s Hazard Communication Standard (HCS) is being updated for the first time since 2012. The 2024 final rule aligns the United States standard with the seventh revised edition of the United Nations Globally Harmonized System (GHS Revision 7), introducing new hazard categories, refined label requirements, and updated safety data sheet content. With the first compliance deadline now days away — May 19, 2026 for substance manufacturers — most chemical companies operating in the United States are running out of time to finish reclassification and SDS updates.
This guide walks compliance specialists, EHS managers, and regulatory affairs professionals through every operational change introduced by the May 2024 final rule, the four-month deadline extension granted in January 2026, and the practical workflow needed to meet the staggered compliance dates running through May 2028. We cover what HCS 2024 changes from HCS 2012, who must comply when, and where to find the underlying classification data.
At a glance
- Regulation: OSHA Hazard Communication Standard, 29 CFR 1910.1200 (HCS 2024)
- Final rule published: May 20, 2024 (89 FR 44144); effective July 19, 2024
- Aligned to: UN GHS Revision 7 (previously Revision 3 in HCS 2012)
- Key extension: January 15, 2026 final rule pushed all compliance dates back four months
- Geographic scope: United States (federal OSHA jurisdictions and 22 OSHA-approved State Plans)
- Affected parties: Chemical manufacturers, importers, distributors, employers, downstream users
- Imminent deadline: May 19, 2026 — substance manufacturers, importers, distributors must comply
- Related tools: ATE Calculator · GHS Label Constructor
Table of Contents
- What is the OSHA Hazard Communication Standard?
- What HCS 2024 Changes from HCS 2012
- Compliance Deadlines and the 2026 Extension
- Practical Compliance Workflow
- Frequently Asked Questions
- How GHS Pictograms Tools Help
What is the OSHA Hazard Communication Standard?
OSHA promulgated the original Hazard Communication Standard in 1983 to standardize how chemical hazards are communicated to U.S. workers. The standard requires manufacturers and importers at the top of the supply chain to evaluate the hazards of the chemicals they produce or import, then transmit that information downstream through container labels and Safety Data Sheets (SDSs). Employers must maintain a written hazard communication program, train employees on hazardous chemicals in their workplace, and keep SDSs accessible.
The 2012 update — sometimes called HazCom 2012 — first aligned the U.S. standard with the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS), specifically Revision 3. Compliance with that update was phased in between 2013 and 2016. Since then, the UN has published several further GHS revisions: Revisions 4 through 9, and most recently Revision 11 in 2025.
By 2022, the gap between the U.S. standard (still on GHS Rev 3 logic) and what manufacturers had to use abroad — GHS Rev 7 in the EU under CLP, Canada’s WHMIS 2015, and several Asian frameworks — created costly duplication. OSHA published a notice of proposed rulemaking in February 2021 and finalized the update on May 20, 2024 (89 Federal Register 44144). The amended standard became effective July 19, 2024, with tiered compliance dates running through 2028.
For a comparison of how different jurisdictions adopt UN GHS revisions, see our country-by-country UN GHS implementation map.
- May 20, 2024 Final Rule Published — 89 FR 44144
- May 19, 2026 Substances · Manufacturers — SDS, labels, classification
- Nov 20, 2026 Substances · Employers — Workplace labels, training, written program
- Nov 19, 2027 Mixtures · Manufacturers — SDS, labels, classification
- May 19, 2028 Mixtures · Employers — Workplace labels, training, written program
What HCS 2024 Changes from HCS 2012
Alignment with GHS Revision 7
The headline change is the move from GHS Revision 3 to GHS Revision 7. Four full editions of GHS guidance were skipped, so the cumulative changes are substantial. Most of the new and amended provisions in HCS 2024 trace directly to additions adopted by the UN Sub-Committee of Experts on the GHS between 2009 and 2017. The result is closer alignment with EU CLP (which uses the same GHS Rev 7 logic) and with Canada’s WHMIS framework — easing label and SDS reuse for multinational manufacturers.
New hazard classes and categories
Flammable gases are restructured into more granular subcategories. HCS 2012 had Categories 1 and 2; HCS 2024 introduces Category 1A and Category 1B, with Category 1A further split into pyrophoric gases and chemically unstable gases. This pattern mirrors the GHS Rev 7 structure and aligns with how flammable gases are already classified for transport.
Aerosols gain a new Category 3 — for non-flammable aerosols that may still pose pressure-related hazards. Previously, only flammable aerosols (Categories 1 and 2) were classified under HCS. Non-flammable aerosols now fall under HazCom and require labels.
Desensitized explosives become a distinct hazard class with five categories, separating them from generic flammable solids and liquids.
Chemicals under pressure is a new hazard class for substances or mixtures stored under gas pressure. A January 8, 2025 corrective rule clarified the definitions of “chemicals under pressure” and “liquid” after several drafting issues were identified in the original final rule.
Label and packaging changes
Several practical label changes reduce burden on manufacturers without weakening the information employees receive:
- Released for shipment. Containers already in the distribution chain when a hazard reclassification occurs do not need to be relabeled. Manufacturers may instead include the updated label with each subsequent shipment.
- Electronic label transmission. Labels may now be transmitted electronically — but only when the recipient explicitly agrees to that arrangement.
- DOT pictogram coexistence. When a container bears a U.S. Department of Transportation pictogram for a given hazard, the corresponding HCS pictogram for the same hazard is now optional rather than prohibited. This clarifies a long-standing inconsistency.
- Small containers. If the immediate outer package contains the full hazard information, very small inner containers may carry abbreviated labels — product identifier, pictogram, and a statement directing the user to the outer package.
SDS content updates
Section 9 (physical and chemical properties) of the SDS template adds GHS Revision 7 endpoints — particle size and shape, where relevant — and refines existing entries. Section 11 (toxicological information) and Section 12 (ecological information) accept the broader hazard classes added by GHS Rev 7. Manufacturers should also expect cross-checks against the corrective rule of January 8, 2025, which fixed several drafting errors in the original final rule.
Trade secrets and “reasonably anticipated use”
HCS 2024 gives manufacturers more flexibility to claim concentration ranges of ingredients as a trade secret on the SDS, provided the actual concentration falls within the disclosed range and the range is not so broad as to mislead downstream users. Hazard classifications must also now consider chemical reactions that occur under conditions of “reasonably anticipated use,” not just the chemical’s properties at rest. This is a less drastic interpretation than the original 2021 proposal, which would have required a generic safe-use evaluation.
Compliance Deadlines and the 2026 Extension
OSHA adopted a tiered compliance schedule in the May 2024 rule. Manufacturers, importers, and distributors face deadlines first, followed by employers, who depend on suppliers to issue compliant SDSs and labels before they can update their workplace materials. The schedule splits further by substances versus mixtures.
The original deadlines drew significant industry pushback. In July 2025, a coalition of 19 trade associations submitted a letter to OSHA documenting unresolved questions in the 2024 rule and asking for additional guidance. Citing the absence of finalized guidance materials, OSHA published a final rule on January 15, 2026 (91 Federal Register 1695) extending all compliance dates by four months. The agency invoked the “good cause” exception under the Administrative Procedure Act, bypassing notice-and-comment rulemaking on the grounds that the imminent January 19, 2026 deadline made formal procedure impractical.
Updated compliance schedule
| Group | Substance/Mixture | Original deadline | Extended deadline |
|---|---|---|---|
| Manufacturers, importers, distributors | Substances | January 19, 2026 | May 19, 2026 |
| Employers (workplace, training, written program) | Substances | July 20, 2026 | November 20, 2026 |
| Manufacturers, importers, distributors | Mixtures | July 19, 2027 | November 19, 2027 |
| Employers (workplace, training, written program) | Mixtures | January 19, 2028 | May 19, 2028 |
Two important nuances apply.
Transitional flexibility, set out in 29 CFR 1910.1200(j)(4), remains intact. Between May 20, 2024 and the applicable deadline, regulated entities may comply with HCS 2012, HCS 2024, or any combination of the two. This lets manufacturers stage updates incrementally rather than performing a single cutover.
State Plan jurisdictions must adopt the federal HCS 2024 update, but their own implementation timelines may differ. The 22 OSHA-approved State Plans have six months to adopt federal updates, though most align their schedules with federal dates. Manufacturers selling into California, Washington, Oregon, or other State Plan states should confirm local effective dates with the relevant agency.
The four-month extension is not a grace period. OSHA has stated that further reprieves are not anticipated. Employers and manufacturers should treat the new dates as firm. The extension exists to give OSHA time to publish final guidance documents — not to ease enforcement pressure.
For SDS workflows that involve mixture reclassification ahead of the November 2027 deadline, our ATE Calculator computes acute toxicity estimates from component data using GHS Rev 7 arithmetic.
Practical Compliance Workflow
The workflow below covers what a substance manufacturer should be doing in May 2026 to meet the May 19 deadline, or — if the deadline has just passed — what closeout activities must be in place.
Step-by-step compliance workflow
- Inventory your substances. List every substance in your catalog. For each, record CAS number, current HCS 2012 classification, and the supplier of underlying hazard data.
- Reclassify under GHS Revision 7. Apply the updated criteria. Most substances will see no change in core hazard classes, but flammable gases, certain aerosols, and chemicals under pressure may shift category.
- Update Safety Data Sheets. Section 9 (physical and chemical properties) and Section 2 (hazards identification) are the most likely to change. Use the corrected definitions from the January 8, 2025 corrective rule when redrafting Section 9 entries.
- Generate compliant labels. Apply the GHS Rev 7 hazard pictograms, signal word, and updated H- and P-statements. The GHS Label Constructor generates HCS-compliant labels with correct pictogram sizing for all five CLP volume tiers, which match the practical packaging sizes used by U.S. manufacturers.
- Notify distributors and customers. Provide updated SDSs to downstream recipients. If electronic transmission is used, document the recipient’s agreement.
- Document the changeover. Keep records of when each product was reclassified, when revised SDSs were sent, and when label stock was updated. OSHA inspectors will look for this audit trail during enforcement actions.
Practical example: Toluene (CAS 108-88-3)
Toluene is a common industrial solvent listed in CLP Annex VI with the harmonized classification of Flammable Liquid Category 2, Skin Irritation Category 2, Reproductive Toxicity Category 2, STOT Single Exposure Category 3, STOT Repeated Exposure Category 2, and Aspiration Toxicity Category 1. Under HCS 2012, the same classification structure applied (drawing on GHS Rev 3 criteria). Under HCS 2024, the core hazards do not change — toluene remains a Cat 2 flammable liquid — but the SDS Section 9 properties section requires GHS Rev 7-aligned data fields, and the workplace label must follow the current HCS 2024 pictogram rendering.
For the full hazard profile, signal word, H-statements, and P-statements, see Toluene on GHSSymbols.
Common compliance gaps
The most frequent issues OSHA cites in HazCom inspections are missing or outdated SDSs in the workplace, generic written hazard communication programs that do not match actual chemical inventories, and inadequate employee training records. None of these are HCS 2024-specific — they are perennial — but the regulation update creates a natural prompt to close them during the same compliance review.
Frequently Asked Questions
What is HazCom?
HazCom is the common name for OSHA’s Hazard Communication Standard, codified at 29 CFR 1910.1200. It establishes the framework for how chemical hazards must be communicated to workers in U.S. workplaces — through container labels, Safety Data Sheets, written hazard communication programs, and employee training. The standard applies to any employer whose employees may be exposed to hazardous chemicals.
What is the purpose of a HazCom program?
A workplace HazCom program documents how an employer meets the requirements of 29 CFR 1910.1200. It identifies the person responsible for compliance, lists hazardous chemicals present in each work area, describes how labels and SDSs are maintained and accessed, outlines employee training procedures, and explains how non-routine task hazards are handled. OSHA requires the program to be in writing and available to employees, designated representatives, and OSHA inspectors on request.
What is HazCom training?
HazCom training prepares employees who may be exposed to hazardous chemicals to recognize hazards in their work area, read labels and Safety Data Sheets, follow safe handling procedures, and respond to emergencies. Training is required at initial assignment and whenever a new chemical hazard is introduced. Under HCS 2024, employers must also provide additional training on the updated label format, new hazard categories, and any reclassifications affecting chemicals already in inventory.
What is the HazCom standard?
The HazCom standard is OSHA’s regulation at 29 CFR 1910.1200. The current version was promulgated by the May 20, 2024 final rule (89 FR 44144), as amended by the January 8, 2025 corrective rule and the January 15, 2026 deadline-extension rule (91 FR 1695). It aligns U.S. hazard communication with the seventh revised edition of the United Nations Globally Harmonized System.
Does HCS 2024 apply to laboratories?
Laboratories are not exempt from HazCom, but a separate OSHA standard — 29 CFR 1910.1450, the Laboratory Standard — addresses chemical safety in non-production laboratory settings. Lab employers must still comply with HazCom labeling and SDS access requirements, but the Lab Standard’s Chemical Hygiene Plan replaces some of the written program elements.
How GHS Pictograms Tools Help
If you are working through HCS 2024 compliance for a U.S. portfolio, three tools on this site can speed up specific steps.
GHS Label Constructor generates fully compliant container labels with correct pictogram sizing for all five CLP volume tiers, which match the practical packaging sizes used by U.S. manufacturers. → Open Label Constructor
ATE Calculator computes acute toxicity estimates from component data — essential for the November 2027 mixture reclassification deadline. The calculator uses the same arithmetic specified in GHS Rev 7 Annex 9 and outputs a printable summary. → Open ATE Calculator
GHS Pictogram Library provides downloadable, regulation-compliant SVG and PNG versions of all nine GHS pictograms. Eight of the nine are required under HCS 2024 — the environmental pictogram is optional under federal OSHA. → Browse pictograms
For underlying hazard data on individual substances, GHSSymbols.com covers 4,178 CLP Annex VI entries with full classification details.
Key takeaways
- HCS 2024 aligns U.S. hazard communication with UN GHS Revision 7, closing a multi-revision gap that had grown since the 2012 alignment with Revision 3.
- The May 19, 2026 substance manufacturer deadline is the most pressing date. It applies to anyone who manufactures, imports, or distributes pure substances in the United States.
- A four-month extension was granted in January 2026 to allow OSHA to publish final guidance, but no further extensions are anticipated.
- Mixture deadlines run later — November 19, 2027 for manufacturers and May 19, 2028 for employers — but mixture reclassification is more complex and should not be delayed.
- Transitional flexibility under 29 CFR 1910.1200(j)(4) lets regulated entities use HCS 2012, HCS 2024, or any combination of both until the applicable deadline arrives.
Related articles in this hub
- UN GHS Implementation by Country: 2026 Status Map
- GHS Label Constructor for HCS 2024 Labels
- ATE Calculator for Mixture Classification
Sources
- OSHA Final Rule: Hazard Communication Standard. 89 Fed. Reg. 44144, May 20, 2024. Available at: https://www.federalregister.gov/documents/2024/05/20/2024-08568/hazard-communication-standard
- OSHA Final Rule: HCS Compliance Date Extension. 91 Fed. Reg. 1695, January 15, 2026. Available at: https://www.federalregister.gov/documents/2026/01/15/2026-00653/hazard-communication-standard
- OSHA HCS 2024 Compliance Date Extension Notice. Available at: https://www.osha.gov/hazcom/rulemaking/extension
- 29 CFR 1910.1200 — Hazard Communication. Code of Federal Regulations, current version. Available at: https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1910/subpart-Z/section-1910.1200
- United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS), Seventh Revised Edition. UN Economic Commission for Europe, 2017. Available at: https://unece.org/transport/dangerous-goods/ghs-rev7-2017
- Substance classification data referenced in this article is sourced from the GHSSymbols.com Hazards Database, derived from ECHA CLP Annex VI list of harmonised classifications, last synchronised in March 2026.