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Understanding signal words: “Danger” and “Warning” under the Hazard Communication Standard

Under OSHA’s Hazard Communication Standard (HCS), 29 CFR 1910.1200, chemical hazard information must be communicated clearly to employees—primarily through hazard communication labels, Safety Data Sheets (SDSs), and training. One of the most visible (and often misunderstood) parts of a compliant label is the signal word.

Many people search for “signal words danger and …” because they’re trying to understand what comes next: Danger and what? Warning and what? In the HCS-aligned GHS system, the key point is this: signal words communicate severity, and they work alongside pictograms, hazard statements, and precautionary statements to provide a complete hazard message.

If your organization stores or uses hazardous chemicals, a centralized SDS and labeling workflow—such as SwiftSDS—can help keep signal words, label elements, and SDS information consistent across your chemical inventory.

What are signal words on labels?

Signal words on labels are standardized terms that indicate the relative level of hazard severity for a chemical. OSHA’s HCS, aligned with the Globally Harmonized System (GHS), recognizes only two signal words:

  • Danger (more severe hazards)
  • Warning (less severe hazards)

A signal word is required on shipped container labels when a chemical is classified as hazardous and the relevant hazard class/category calls for one.

“Danger” vs. “Warning”: how OSHA intends them to be used

The system is intentionally simple:

  • Danger is used for higher hazard categories (for example, more severe acute toxicity or more severe skin corrosion).
  • Warning is used for lower hazard categories within the same hazard class.

Only one signal word appears on a label—even if multiple hazards apply. When both would be triggered, Danger takes precedence.

Important: Signal words don’t replace training. OSHA expects employers to train employees on label elements and SDSs under 29 CFR 1910.1200(h).

Signal words and the required elements of hazard communication labels

OSHA’s HCS requires specific label elements for shipped containers of hazardous chemicals. While many teams focus heavily on pictograms, signal words are equally important because they influence how workers interpret urgency.

Under 29 CFR 1910.1200(f), compliant hazard communication labels must include:

  • Product identifier
  • Supplier identification (name, address, telephone number)
  • Signal word (when required)
  • Hazard statement(s)
  • Precautionary statement(s)
  • Pictogram(s)

Why label consistency matters in the workplace

In real facilities, labels aren’t just on shipped drums—they’re also copied onto secondary containers, used in mobile operations, and referenced during maintenance tasks. Inconsistent signal words can create confusion, especially when the SDS says one thing and the workplace label shows another.

SwiftSDS helps reduce this risk by providing a centralized SDS library and chemical inventory tools so EHS teams can standardize how SDS data (including sds signal words) is referenced across sites and departments.

Pictograms used on labels must be understood alongside signal words

A common compliance misconception is that pictograms alone are enough. In reality, pictograms used on labels must be presented with the other required label elements (including the signal word), and employees must be trained to understand the full message.

Pictograms provide quick visual hazard recognition (for example, flame for flammables, skull and crossbones for severe acute toxicity). The signal word adds severity context, and hazard/precautionary statements provide the specific nature of the hazard and protective measures.

How pictograms and signal words work together (practical example)

Consider a product classified as a flammable liquid and causing serious eye damage:

  • The flame pictogram cues flammability.
  • The corrosion pictogram cues serious eye damage/skin corrosion.
  • The signal word may be Danger if the categories are severe.
  • Hazard statements specify what’s happening (e.g., “Highly flammable liquid and vapor” and “Causes serious eye damage”).

This combination supports quick decisions at the point of use: PPE selection, storage segregation, ignition control, and emergency response.

Where signal words appear on the SDS (and why “SDS signal words” matter)

The SDS is the deeper technical reference behind the label. While the OSHA SDS format requires 16 sections, the signal word most commonly appears in Section 2: Hazard(s) Identification.

That’s why “sds signal words” is a useful compliance checkpoint: the label signal word should align with the SDS classification and hazard statements.

If the SDS and label disagree

Misalignment can happen when:

  • An SDS is outdated or superseded
  • A supplier reclassifies a product and issues a revised SDS
  • A workplace label is created manually and isn’t updated

Under 29 CFR 1910.1200(g), employers must maintain SDSs for hazardous chemicals and ensure they are readily accessible to employees. Keeping current SDSs makes it far easier to verify correct label elements—including signal words.

SwiftSDS supports this by storing SDSs in a secure cloud-based location, making it easier to distribute updates, avoid old revisions, and provide mobile access so employees can check Section 2 quickly in the field.

Training requirements: helping workers interpret “Danger” and “Warning” correctly

OSHA’s HazCom training requirement (29 CFR 1910.1200(h)) includes ensuring employees understand:

  • Label elements (including signal words on labels)
  • SDS format and how to find key information
  • Measures to protect themselves from hazards

Training tips that reduce incidents and improve compliance

  • Teach employees that “Danger” means the more severe hazard category—not necessarily that an immediate emergency is occurring.
  • Use real examples from your facility’s SDS library (especially Section 2).
  • Reinforce that pictograms, signal words, and hazard statements must be read together.
  • Practice “find it fast” drills: locate signal word, hazard statements, and key PPE guidance on an SDS.

Managing multi-site label and SDS accuracy with SwiftSDS

Organizations often struggle with SDS and labeling consistency because chemicals move between locations, supervisors create secondary labels differently, or SDS binders aren’t updated. These gaps can undermine HazCom compliance and worker understanding.

SwiftSDS helps address these SDS management challenges by enabling:

  • A Centralized SDS Library for consistent access and revision control
  • OSHA compliance support aligned with 29 CFR 1910.1200 expectations
  • GHS support for classification and labeling alignment
  • Chemical inventory management to track where hazardous chemicals are used and stored
  • Mobile access so workers can retrieve SDS information instantly

If you’re building or improving a HazCom program, consider pairing consistent workplace labeling practices with a modern SDS management system. You can also explore our related resources, including Safety Data Sheet management and Hazard Communication Standard compliance.

Conclusion: get signal words right to strengthen HazCom compliance

Signal words are a small label element with a big impact. Getting “Danger” and “Warning” right—and ensuring alignment between hazard communication labels, pictograms, and SDS Section 2—supports clearer hazard recognition and helps fulfill OSHA HazCom requirements.

The goal of HazCom isn’t paperwork—it’s ensuring employees can quickly understand chemical hazards and protect themselves.

Call to action: Streamline your SDS access, keep revisions current, and standardize hazard information across labels and locations with SwiftSDS. Contact us to schedule a demo and see how SwiftSDS can support your HazCom program end-to-end.