GHS, the Globally Harmonized System of Classification and Labelling of Chemicals, is the framework behind nearly every Safety Data Sheet you'll ever handle. Understanding how it classifies hazards isn't just academic; it directly drives what shows up on your Tier II report.
What GHS actually standardizes
Before GHS, different countries and even different companies used inconsistent hazard classification and labeling systems, making it hard to compare hazard information across products or borders. GHS standardizes hazard classes, pictograms, signal words, and hazard statements so that a classification means the same thing regardless of who wrote the SDS.
Reading SDS Section 2: an annotated example
Section 2 of the SDS, Hazard identification, is where the classification lives. Under OSHA's Hazard Communication Standard (29 CFR 1910.1200), it carries the hazard classification, signal word, hazard statements, pictograms and precautionary statements. Here's how to read one, using acetone as it is commonly classified.
| Source text (SDS Section 2) | Interpretation |
|---|---|
| Flammable liquid, Category 2 | Physical hazard class (flammable liquid) and the category within it |
| Eye irritation, Category 2A | Health hazard class and category |
| Specific target organ toxicity, single exposure, Category 3 | Health hazard class; the hazard statement H336 below identifies the effect (drowsiness or dizziness) |
| Signal word: Danger | One signal word per product: "Danger" for more severe hazards, "Warning" for less severe ones |
| Pictograms: flame; exclamation mark | Flame for the flammability hazard; exclamation mark for the eye irritation and drowsiness/dizziness hazards |
| H225 Highly flammable liquid and vapour | Hazard statement for the flammable liquid classification |
| H319 Causes serious eye irritation | Hazard statement for the eye irritation classification |
| H336 May cause drowsiness or dizziness | Hazard statement for the single-exposure target organ classification |
| Precautionary statements: [as listed on your SDS] | Recommended measures for prevention, response, storage and disposal; read them from the current SDS |
Illustrative only. Classifications can differ between suppliers, grades and formulations, so always read Section 2 of the current SDS for the exact product you hold.
Each line on the left should trace to a line on the right: every hazard statement and pictogram should correspond to a listed classification. When they don't line up, that's a data problem to resolve before the information goes into your inventory or reports.
The structure of a GHS-compliant SDS
A GHS-format SDS follows a standardized 16-section structure, covering everything from identification and hazard classification to handling, storage, exposure controls, and disposal. For EPCRA reporting purposes, a handful of these sections matter most: hazard identification (Section 2), composition and ingredients (Section 3), and physical and chemical properties (Section 9), all of which feed directly into the hazard categories and physical states you're required to report on your Tier II form.
Physical vs. health hazard classes
GHS separates hazards into physical hazard classes (flammability, reactivity, corrosivity to metals, and similar) and health hazard classes (acute toxicity, carcinogenicity, skin and eye irritation, and others). Tier II reporting asks you to report which hazard categories apply to each chemical. Getting this classification wrong doesn't just create a data quality issue. It can misrepresent the actual risk profile responders are planning around.
From SDS hazards to Tier II hazard categories
The Tier II form asks for each reportable chemical's physical and health hazard categories. A reviewer reads the classifications in SDS Section 2 (and the composition in Section 3 for mixtures), then selects the matching categories from the current EPA Tier II forms and instructions or your state's version of them. Record which SDS revision the selection came from, so it can be rechecked when the SDS changes.
A GHS classification doesn't decide whether you have to file. Tier II applicability depends on whether OSHA requires you to maintain an SDS for the chemical and whether the maximum amount on-site at any one time reached the threshold: 10,000 lbs, or 500 lbs or the TPQ (whichever is lower) for an Extremely Hazardous Substance. The hazard categories describe a chemical once it is reportable.
Verify against the source document whenever something looks off. Compare your record with the supplier's current SDS; you can search safety data sheets to find a product and view its SDS summary (downloading the document requires platform access).
If you use AI SDS extraction to structure hazard data from SDS PDFs, treat the result as a draft for review. NeoTech's extraction assigns a confidence score to every field and flags low-confidence fields for review, but a person should still confirm the hazard categories before they reach a report.
Human review for missing or inconsistent hazard data
- SDS is the current revision for the exact product, supplier and formulation in inventory
- Section 2 contains a GHS classification, not only a legacy rating system
- Every pictogram and hazard statement corresponds to a listed classification, and vice versa
- Signal word is consistent with the classifications listed
- For mixtures, the Section 2 classification is for the product as supplied; component data from Section 3 is recorded separately
- Changes from the previous SDS revision are noted and the inventory record updated
- Tier II hazard categories are selected from the current instructions and match Section 2
- Missing, illegible or conflicting data is sent back to the supplier with the request date recorded
- Reviewer name and review date are recorded
Where classification errors commonly happen
- Reading an outdated or non-GHS-format SDS that uses a legacy hazard system instead of current classification
- Misreading a mixture's classification, which can differ from any single ingredient's individual classification
- Applying a hazard class from a similar but not identical product, when a supplier updates a formulation
- Manually transcribing hazard data from a scanned or image-only SDS, where transcription errors are easy to introduce
Why this matters beyond compliance paperwork
Hazard classification isn't just a reporting formality, it's the information your LEPC and fire department are relying on to plan an actual emergency response. An incorrect hazard class on a Tier II report is the kind of error that only becomes visible in the worst possible circumstances.
Official source
SDS content and hazard classification requirements in the US are set by OSHA's Hazard Communication Standard, 29 CFR 1910.1200. Tier II reporting, including the hazard categories on the form, is established under the Emergency Planning and Community Right-to-Know Act (EPCRA); see EPA Tier II forms and instructions for the form. Always verify current state-specific rules with your SERC.
SourceHazard Communication | OSHARegulatory statements in this article were checked against the official sources linked above on .