How to author an SDS for the US

Authoring a Safety Data Sheet (SDS) for the US market is both a regulatory obligation and a critical safety communication task.  

Whether you are a chemical manufacturer, importer, or distributor, understanding how to write a compliant SDS under OSHA’s Hazard Communication Standard (HazCom), updated to align with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Revision 7, is essential for staying on the right side of the law, and for protecting workers. 

This guide reflects the current standard which is HazCom 2024, published in the Federal Register on 20 May, 2024, and effective 19 July, 2024. If your SDSs were authored under HazCom 2012, it is time to review and update them. 

HazCom 2024: What changed and why it matters for SDS authors

For over a decade, US SDSs were governed by HazCom 2012, which aligned with GHS Revision 3. In the years since, the UN continued updating the GHS every two years, leaving HazCom 2012 increasingly out of step with global best practices and international trading partners. OSHA’s 2024 final rule closes that gap, aligning 29 CFR 1910.1200 primarily with GHS Revision 7, with select elements drawn from Revision 8. 

The changes are more targeted than the sweeping overhaul of 2012, but they are significant, particularly for SDS authors working with aerosols, flammable gases, pressurized chemicals, and desensitized explosives. Updated hazard classifications, revised SDS content requirements, new physical and chemical property fields, and strengthened trade secret provisions all require attention. 

What HazCom 2024 changes for SDS authors

Updated hazard classifications

The most impactful HazCom 2024 changes for SDS authors involve revised hazard classes and categories.  

If your products fall into any of the following areas, your Section 2 classification and associated label elements will need to be reviewed and likely revised: 

Flammable gases 

Category 1 has been subdivided into Categories 1A and 1B, with pyrophoric gases and chemically unstable gases now specifically required to be classified as Category 1A. These subcategories carry different hazard and precautionary statements and communicate more precisely how a gas behaves and what risks it poses during use, storage, or transport. 

Aerosols 

The “Flammable Aerosols” hazard class has been renamed simply “Aerosols” and expanded. A new Category 3 now captures non-flammable aerosols, so products that do not meet flammability criteria but may still present physical hazards such as pressure build-up or container bursting. Flammable aerosols remain in Categories 1 and 2. Under HazCom 2012, many aerosols were classified as “gases under pressure”; that classification no longer applies to most aerosol containers, and SDSs must be updated accordingly. 

Chemicals under pressure 

A new hazard class drawn from GHS Revision 8 addresses liquids and solids pressurized with a gas, where the aerosol and gases-under-pressure classifications do not accurately apply. This class includes Categories 1 to 3. 

Desensitized explosives 

Categories 1 to 4 have been adopted, providing clearer hazard communication for these materials. 

Combustible dust 

A formal definition has been added to the standard, though it was already treated as a hazard under HazCom 2012. 

Updated Section 9: Physical and chemical properties 

HazCom 2024 expands the required physical and chemical properties in Section 9. Property names have been updated, and new properties, including particle characteristics, have been added. SDS authors must ensure that all available data is reported; if a value such as evaporation rate or odor threshold exists in the technical literature or from testing, it should appear in the SDS. 

Revised hazard and precautionary statements 

Hazard and precautionary statements have been updated to align with GHS Revision 7 wording. HazCom 2024 also now permits minor textual variations to avoid redundancy, which gives SDS authors slightly more flexibility in how statements are presented, particularly where space is limited. 

Expanded trade secret provisions 

Section 3 authoring is affected by new trade secret rules. HazCom 2024 expands confidential business information (CBI) provisions, enabling manufacturers to withhold concentration ranges as trade secrets, provided they select from a prescribed list of acceptable ranges. Critically, the update also strengthens protections for workers and first responders by limiting the circumstances in which trade secret claims can prevent disclosure of hazard information on SDSs. SDS authors must carefully balance these competing obligations when documenting ingredient information. 

Downstream use hazards 

HazCom 2024 now requires SDSs to include hazards that may arise during typical downstream use, for example, dusts generated during processing, or reactivity triggered by mixing or heating. This expands hazard communication beyond the product “as supplied” and requires SDS authors to think carefully about foreseeable use scenarios when completing Sections 2, 10, and 11. 

Key principles for US SDS authoring

Get the hazard classification right 

The foundation of a compliant SDS is an accurate GHS hazard classification under the updated HazCom 2024 criteria. Misclassification, or failure to update classifications to reflect the new categories for aerosols, flammable gases, and chemicals under pressure is a primary compliance risk in the current transition period. 

Use plain, precise language 

OSHA’s HazCom standard requires SDSs to be written in English and understandable to workers. A person on a manufacturing floor should be able to read Section 4 (First-aid measures) and know exactly what to do in an emergency. Accuracy and clarity must not be in conflict and both are required. 

Avoid over-classification as well as under-classification 

The compliance conversation around hazard classification tends to focus on the risks of under-classification, and rightly so — failure to identify a genuine hazard can put workers in danger. However, over-classification presents its own significant risks that SDS authors should not overlook. When products are routinely assigned hazard categories more severe than their physical properties warrant, workers can become desensitized to hazard signals. If every chemical in a facility appears equally dangerous, none stands out — and employees may apply less care precisely where more is needed. Over-classification also has financial consequences throughout the supply chain, including unnecessary PPE requirements and increased downstream handling costs. The goal must always be accurate classification. 

Start with physical properties, not ingredients 

A common authoring error is building a hazard classification from the bottom up, starting with the ingredient list and working toward the hazard. The more reliable and consistent approach is the reverse: start with the physical properties of the finished product and let those drive classification. The pH, flashpoint, boiling point, vapor pressure, and other measurable properties of the end product are what actually determine how a chemical behaves in use, and they account for more than 90 percent of the information on a completed SDS. Ingredients matter, but ingredients that are individually hazardous may lose those properties when combined — acids and bases are both corrosive individually, for example, but may neutralize each other in a mixture. Classifying from the hazard down, grounded in measured physical properties, produces more accurate, more consistent, and more defensible SDSs. 

Keep exposure limits current 

Section 8 is frequently scrutinized during OSHA inspections. Always include the most current OSHA PELs, ACGIH TLVs, and NIOSH RELs for all relevant components. OSHA’s published PELs are notoriously outdated, best practice is to include all three sets of values and recommend compliance with the most protective limit. 

Address US-specific regulatory requirements 

Section 15 sets US SDSs apart from those authored for other markets. A well-authored SDS covers TSCA inventory status, SARA 302/304/311/312/313 reporting thresholds, CERCLA hazardous substances, and applicable state regulations, particularly California Proposition 65 warnings, New Jersey RTK requirements, and Pennsylvania Hazardous Substance Survey obligations. 

Verify DOT transport classifications 

Section 14 requires DOT classification under 49 CFR, not just IATA or IMDG data. Many SDSs imported from non-US markets carry UN classifications without verifying US DOT proper shipping names, hazard classes, and packing groups. This must be independently verified for every product sold or shipped in the United States. 

HazCom 2024 compliance deadlines 

HazCom 2024 introduced a phased compliance timeline. In January 2026, OSHA published a further final rule extending the original deadlines by four months, citing the need to finalize critical guidance documentation. The current compliance schedule is: 

• Manufacturers and importers of substances, May 19, 2026 

• Manufacturers and importers of mixtures, November 19, 2027 

• Employers, May 19, 2028 (six months after the mixture manufacturer deadline) 

During the transition periods, chemical manufacturers, importers, distributors, and employers may comply with the 2012 version of the standard, the 2024 version, or both. However, given that the substance deadline is imminent, organizations that have not begun reviewing and updating their SDSs should act without delay. 

Ongoing SDS update obligations 

Compliance with HazCom 2024 does not end at the initial authoring stage. Once an SDS is in circulation, OSHA imposes ongoing update obligations that manufacturers, importers, and employers must manage actively. 

Under 29 CFR 1910.1200, an SDS must be revised whenever new and significant information about a chemical’s hazards or protective measures becomes available. There is no fixed annual or periodic review cycle — updates are event-driven, triggered by new toxicological or hazard data, product formulation changes, regulatory reclassification, updated exposure limits, or the discovery of previously unlisted hazards or impurities. Once such information is identified, the revised SDS must be completed within three months, and any corresponding labels must be updated within six months. 

Manufacturers and importers are required to provide updated SDSs downstream at two specific points: at the time of the first shipment of a product, and with the next shipment following any SDS revision. Importantly, OSHA does not require automatic redistribution of updated SDSs to all prior customers in the absence of a new shipment — but this places a corresponding responsibility on employers to monitor supplier communications and proactively replace outdated SDSs in their workplace libraries when updates are received. 

Common SDS authoring mistakes to avoid

• Failing to update hazard classifications for aerosols, flammable gases, or chemicals under pressure to reflect HazCom 2024 categories. 

• Copying SDSs from EU or pre-2024 sources without adapting Section 15 for US regulations and Section 14 for DOT requirements. 

• Generic boilerplate in Section 8 that does not reflect the actual hazards of the specific product. 

• Omitting CAS numbers or using concentration ranges that do not satisfy HazCom 2024’s updated ingredient disclosure rules. 

• Using outdated hazard or precautionary statement wording from HazCom 2012 for newly classified or reclassified hazard categories. 

• Ignoring downstream use hazards that must now be addressed on the SDS. 

Authoring a compliant US Safety Data Sheet under HazCom 2024 demands accurate hazard classification against updated GHS Revision 7 criteria, knowledge of new and revised hazard categories, familiarity with US-specific regulatory requirements, and a commitment to clear communication. With compliance deadlines now actively running, organizations that manage chemical portfolios should prioritize a systematic review of their SDS libraries. 

Read further information on pitfalls when authoring SDS.