GHS / HazCom term · Glossary
Skin Sensitization
Verified vs OSHA sources · 2026-10-05
A GHS health-hazard class for chemicals that cause an allergic skin reaction (allergic contact dermatitis) after skin contact. The first exposure “induces” the allergy; later exposures “elicit” the reaction, so once a worker is sensitized even small amounts can trigger it. Skin sensitizers carry the exclamation-mark pictogram (GHS07).
Also known as: allergic contact dermatitis, dermal sensitizer
Skin Sensitization at a glance
- An immune (allergic) reaction — different from direct chemical irritation or corrosion.
- Two phases: induction (first becoming allergic) then elicitation (the reaction).
- Once sensitized, very small amounts can trigger a reaction.
- Category 1 (with sub-categories 1A/1B); pictogram GHS07, “Warning,” H317.
In plain English
How a label flags a chemical that can make you allergic to it. The first contacts may do nothing visible, but once your immune system is “primed,” later contact — even a tiny amount — brings on an itchy, blistering rash.
What the rule says
“Skin sensitization refers to an allergic response occurring after skin contact with a substance or mixture.”
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 App A.4Read on eCFR / OSHA.gov
Example
Epoxy resins and chromates are common skin sensitizers. A worker may handle epoxy for weeks with no problem (induction), then develop a spreading, blistering dermatitis from a single later contact (elicitation). The label carries GHS07, “Warning,” and H317, “May cause an allergic skin reaction.”
Why it matters
Skin sensitization can end a career — once allergic, a worker may not be able to work near the chemical at all. Treating a sensitizer as a simple irritant, or omitting H317, denies workers the warning and is a HazCom classification/labeling issue under 1910.1200.
Skin vs. respiratory sensitization
Both are allergic reactions, but to different routes. Skin sensitization is an allergic skin response (dermatitis) — GHS07, “Warning,” H317. Respiratory sensitization is airway hypersensitivity (occupational asthma) — the more severe GHS08, “Danger,” H334.
Skin vs. respiratory sensitization
| Type | Reaction | Pictogram · signal · H-code |
|---|---|---|
| Skin sensitization | Allergic skin reaction (dermatitis) | GHS07 · Warning · H317 |
| Respiratory sensitization | Airway hypersensitivity (asthma) | GHS08 · Danger · H334 |
Skin Sensitization: frequently asked questions
- What is the difference between skin sensitization and skin irritation?
- Skin sensitization is an allergic immune reaction that develops over time and can be triggered by tiny amounts once you're sensitized (GHS07, H317). Skin irritation is direct, non-allergic inflammation that happens on contact (GHS07, H315). Sensitization is the harder hazard to control.
- What pictogram and statement are used for skin sensitizers?
- The exclamation-mark pictogram (GHS07), the signal word “Warning,” and the hazard statement H317, “May cause an allergic skin reaction.”
- Can someone become sensitized after using a chemical safely for a while?
- Yes. Sensitization has an induction phase — a worker may handle a chemical with no reaction, then become allergic, after which even brief contact elicits dermatitis. This is why sensitizers are flagged regardless of prior tolerance.
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.
ClassificationThe 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.
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.
Sources & verification
- 29 CFR 1910.1200 App A.4 (eCFR / OSHA.gov)
- OSHA — Appendix A to §1910.1200: Health Hazard Criteria (Mandatory)
- UNECE GHS — Part 3: Health Hazards
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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