The GHS corrosive pictogram represents three distinct hazard classes: skin corrosion, serious eye damage, and corrosion to metals. You’ll recognize it as the image of a substance eating through a surface and a hand, printed inside a red diamond border. Each of these three hazards triggers the same symbol, but they involve different risks and different classification criteria.
The Three Hazard Classes
Under the Globally Harmonized System (GHS) of chemical classification, the corrosive pictogram covers hazards to skin, eyes, and metal surfaces. Specifically:
- Skin corrosion/irritation, Category 1 (including sub-categories 1A, 1B, and 1C): Chemicals that cause irreversible destruction of skin tissue. The hazard statement reads “Causes severe skin burns and eye damage” (H314), and the signal word is “Danger.”
- Serious eye damage/eye irritation, Category 1: Chemicals that produce tissue damage in the eye or serious decay of vision that doesn’t fully reverse. The hazard statement is “Causes serious eye damage” (H318), also with the signal word “Danger.”
- Corrosive to metals, Category 1: Chemicals that degrade steel or aluminum at a significant rate. The hazard statement is “May be corrosive to metals” (H290), with the signal word “Warning.”
An important distinction: milder forms of skin and eye hazards, like skin irritation (Category 2) or eye irritation (Category 2A), do not use the corrosive pictogram. Those get the exclamation mark pictogram instead. The corrosive symbol is reserved for the most severe categories.
Skin Corrosion vs. Skin Irritation
The line between corrosion and irritation comes down to one factor: reversibility. Skin corrosion means irreversible damage, specifically visible destruction of tissue through the outer skin layer (epidermis) and into the deeper layer (dermis). Skin irritation, by contrast, is reversible damage from the same kind of exposure. That’s why irritation gets a less severe pictogram.
Skin corrosion is further divided into three sub-categories based on how quickly damage occurs:
- Sub-category 1A: Corrosive response after 3 minutes or less of exposure, observed within 1 hour. These are the most aggressively corrosive substances.
- Sub-category 1B: Corrosive response after more than 3 minutes but no longer than 1 hour of exposure, observed over up to 14 days.
- Sub-category 1C: Corrosive response after more than 1 hour but no longer than 4 hours of exposure, observed over up to 14 days.
All three sub-categories carry the same corrosive pictogram and the signal word “Danger.” The sub-category distinction helps safety professionals assess how quickly a chemical can cause harm, which matters for emergency response planning and protective equipment choices.
Serious Eye Damage Criteria
A chemical qualifies as causing serious eye damage (Category 1) when it produces effects on the cornea, iris, or the membrane lining the eye that don’t fully reverse within a 21-day observation period. This includes severe corneal cloudiness, tissue adhesion, and interference with iris function or sight.
The threshold is strict: even one irreversible outcome in testing can trigger Category 1 classification. Less severe eye effects, like redness or irritation that clears up within days, fall into Category 2A or 2B and use the exclamation mark pictogram instead.
Corrosive to Metals
This hazard class is often overlooked because people associate the corrosive pictogram with bodily harm. But it also applies to chemicals that attack metal surfaces, specifically those that corrode steel or aluminum at a rate exceeding 6.25 mm per year when tested at 55°C. If a substance fails the test on either steel or aluminum, it doesn’t even need to be tested on the other metal to receive the classification.
The signal word for this class is “Warning” rather than “Danger,” reflecting that the risk is to equipment and containers rather than human tissue. Still, a chemical corrosive to metals may also carry skin corrosion or eye damage classifications, meaning multiple hazard statements can appear on a single label alongside the same pictogram.
What Doesn’t Use the Corrosive Pictogram
Several related hazards look like they might belong under the corrosive symbol but don’t. Skin irritation (Category 2), mild skin irritation (Category 3), serious eye irritation (Category 2A), and plain eye irritation (Category 2B) all fall outside the corrosive pictogram’s scope. Categories 2 and 2A use the exclamation mark pictogram with the signal word “Warning.” Categories 3 and 2B carry no pictogram at all, though they may still require hazard statements on the label.
The pattern is consistent: the corrosive pictogram marks the most severe category within each hazard class. If the damage is reversible or mild, a different symbol applies.
Handling Chemicals With This Pictogram
When you see the corrosive pictogram on a chemical label, the primary concern is preventing contact with skin, eyes, and metal surfaces. For skin and eye protection, this typically means chemical-resistant gloves, splash-proof goggles or a face shield, and protective clothing that covers exposed skin. The specific glove material matters: butyl rubber gloves resist highly corrosive acids like sulfuric acid and nitric acid, while natural latex gloves handle most water-based acid and alkali solutions.
Corrosive chemicals also require careful storage. Containers must resist the chemical inside them, and corrosive-to-metals substances need to be kept away from steel or aluminum equipment and shelving that could degrade over time. Checking the Safety Data Sheet (SDS) for the specific product will tell you exactly which materials are compatible and which protective equipment is recommended for that substance.