GHS / HazCom term · Glossary
Classification
Verified vs OSHA sources · 2026-10-05
The process of evaluating the available scientific evidence for a chemical against the GHS criteria to decide whether it is hazardous and, if so, the hazard class and category of each effect. Classification is the first step in HazCom — its result determines every label element (pictogram, signal word, hazard and precautionary statements) and SDS content.
Also known as: hazard classification
Classification at a glance
- Done by the manufacturer or importer — the duty to classify is theirs (1910.1200(d)).
- Evaluates physical, health, and environmental hazards against GHS criteria.
- Its output is the hazard class + category for each effect.
- That output drives every label element and the SDS — it's the foundation of HazCom.
In plain English
Working out exactly how dangerous a chemical is, by the rulebook. You compare the data to GHS criteria, decide which hazard buckets (classes) it falls in and how severe (categories), and that decision dictates everything that goes on the label and SDS.
What the rule says
“Classification means to identify the relevant data regarding the hazards of a chemical; review those data to ascertain the hazards associated with the chemical; and decide whether the chemical will be classified as hazardous according to the definition of hazardous chemical in this section. In addition, classification for health and physical hazards includes the determination of the degree of hazard, where appropriate, by comparing the data with the criteria for health and physical hazards.”
In context
A classification or labeling concept from the UN Globally Harmonized System, adopted into US law through OSHA's Hazard Communication Standard (29 CFR 1910.1200) and its appendices.
Where this is written in OSHA's rules
- 29 CFR 1910.1200(d)Read on eCFR / OSHA.gov
- 29 CFR 1910.1200(c)Read on eCFR / OSHA.gov
Example
To classify acetone, a manufacturer checks its flash point (−20°C) and boiling point (56°C) → Flammable Liquid Category 2; its eye effects → Eye Irritation Category 2A; and its CNS effects → STOT-SE Category 3. Those results then set the pictograms (GHS02, GHS07), signal word (“Danger”), and H-statements that appear on every acetone label.
Why it matters
Classification is where HazCom accuracy is won or lost: every downstream element — pictogram, signal word, statements, SDS — flows from it. An under-classified chemical mislabels the hazard for every worker who handles it, and OSHA cites classification errors directly under 1910.1200(d).
Classification vs. labeling
Classification is the evaluation — deciding the hazard class and category from the evidence. Labeling is the output — putting the resulting pictograms, signal word, and statements on the container. You can't label correctly without classifying first.
What classification determines
| Classification result | Label/SDS element it sets |
|---|---|
| Hazard class(es) present | Which pictogram(s) appear |
| Severity (category) | Signal word — Danger or Warning |
| Class + category | Hazard statement(s) — H-codes |
| Class + category | Precautionary statement(s) — P-codes |
Classification: frequently asked questions
- Who is responsible for classifying a chemical?
- The chemical manufacturer or importer. Under 29 CFR 1910.1200(d) they must evaluate the available evidence and classify the chemical's hazards; employers generally rely on that classification via the SDS and label.
- What does classification determine?
- The hazard class and category of each hazardous effect — which in turn set every label element (pictogram, signal word, hazard and precautionary statements) and the content of the SDS.
- Is classification the same as labeling?
- No. Classification is the evaluation that decides the hazards; labeling is communicating those results on the container. Classification comes first and drives the label.
Related terms
Free tools for this
Governing OSHA standards
More GHS terms
A GHS health-hazard class for the harmful effects that follow a single dose, several doses within 24 hours, or a 4-hour inhalation exposure. Chemicals are sorted into categories by route (oral, dermal, inhalation) using LD50/LC50 cut-offs — Category 1 is the most toxic. OSHA's HazCom standard uses Categories 1–4.
Aspiration HazardA GHS health-hazard class for chemicals that can be fatal if swallowed and then enter the airways — directly or by vomiting — causing chemical pneumonia or lung injury. Thin, low-viscosity hydrocarbons (gasoline, kerosene, lamp oil) are the classic example. It is Category 1, with the health-hazard pictogram (GHS08) and signal word “Danger.”
CarcinogenicityA GHS health-hazard class for chemicals that cause cancer or increase its incidence. GHS (and OSHA's HazCom standard) sorts carcinogens into Category 1A (known human carcinogen), 1B (presumed, from animal evidence), and Category 2 (suspected). Carcinogens carry the health-hazard pictogram (GHS08) and a hazard statement such as H350 (“May cause cancer”).
Chemicals Under PressureA physical-hazard class added by OSHA's 2024 HCS update (aligning with GHS Revision 7) for liquids or solids pressurized with a gas, held in pressure receptacles other than aerosol dispensers and not classified as gases under pressure. It is categorized by the flammability of its contents and always carries the gas-cylinder pictogram (GHS04) for the pressure hazard.
Corrosive to MetalsA GHS physical-hazard class for chemicals that, by chemical action, will materially damage or even destroy metals. It is a single category (Category 1), determined by corrosion-rate testing on steel and aluminum, and uses the corrosion pictogram (GHS05) with the hazard statement H290. It is a separate hazard from skin corrosion, even though both use GHS05.
Desensitized ExplosivesA physical-hazard class added by OSHA's 2024 HCS update (GHS Revision 7) for solid or liquid explosives that have been phlegmatized — wetted or diluted — to suppress their explosive properties for safe transport and storage. It has four categories based on the corrected burning rate, and uses the flame pictogram (GHS02), not the exploding-bomb.
Globally Harmonized System (GHS)An internationally agreed framework created by the United Nations (first adopted in 2003) that standardizes how chemical hazards are classified and communicated — using common hazard classes, pictograms, signal words (Danger / Warning), and coded hazard (H) and precautionary (P) statements on labels and safety data sheets. The US adopted GHS into law through OSHA's 2012 Hazard Communication Standard update.
GHS Revision 7The 7th revision of the UN Globally Harmonized System, which OSHA adopted in its 2024 update to the Hazard Communication Standard (with selected elements of Revision 8). It adds new hazard classes — desensitized explosives and chemicals under pressure — folds pyrophoric and chemically unstable gases into flammable gases, and updates label and SDS provisions. The final rule was effective July 19, 2024, with phased compliance dates.
Sources & verification
- 29 CFR 1910.1200(d) (eCFR / OSHA.gov)
- 29 CFR 1910.1200(c) (eCFR / OSHA.gov)
- OSHA — Hazard Classification Guidance (OSHA 3844)
- 29 CFR 1910.1200 (eCFR)
Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.
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