- Chemical hazard pictograms are the 9 GHS symbols (GHS01–GHS09) – black symbols in a white diamond with a red border that warn of the hazards posed by a substance.
- In the EU their use is governed by the CLP Regulation (EC) No 1272/2008; since 2015 they have replaced the old orange squares with letters (Xi, Xn, T, C, F, O, N, E).
- On the label, pictograms are accompanied by a signal word (“Danger” or “Warning”) and by H statements (hazards) and P statements (precautions).
- An oxidising substance (GHS03 – flame over circle) need not burn itself, but it supplies oxygen and may cause or intensify a fire.
- CLP pictograms are not the same as the coloured ADR transport labels – both types of marking may appear on a package.
In short: chemical hazard pictograms are the globally harmonised warning symbols of the GHS, used in the EU under the CLP Regulation. There are nine of them (GHS01–GHS09): explosive, flammable, oxidising, gas under pressure, corrosive, toxic, harmful/irritant (exclamation mark), serious health hazard and hazardous to the environment. Each takes the form of a black symbol in a white diamond with a red border. On the label they are supplemented by the signal word “Danger” or “Warning” and by H and P statements, while full details are given in the safety data sheet.
What are chemical hazard pictograms?
A chemical hazard pictogram is a graphic symbol that quickly conveys the hazardous properties of a substance or mixture. Pictograms are part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) developed by the United Nations. In the European Union it is implemented by the CLP Regulation (EC) No 1272/2008 – named after Classification, Labelling and Packaging.
Each pictogram is a square set on its point (a diamond) with a red border and a black symbol on a white background. It should cover at least 1/15 of the label area, and no less than 1 cm². A single package may carry several pictograms – for example, concentrated sulfuric acid bears the corrosive pictogram, while petrol carries as many as three (flame, exclamation mark and serious health hazard) plus the environmental pictogram.
Pictograms are mandatory on the packaging of substances and mixtures classified as hazardous – in both professional and consumer sales, for example on cleaning products.
What are the chemical hazard pictograms and what do they mean?
The GHS comprises nine pictograms. Each has a code, a name and assigned hazard classes:
| Code | Symbol | Meaning | Example substances |
|---|---|---|---|
| GHS01 | exploding bomb | explosives, self-reactive substances, some organic peroxides | nitroglycerine, TNT, black powder |
| GHS02 | flame | flammable substances (gases, aerosols, liquids, solids), pyrophoric, self-heating | petrol, ethanol, acetone, propane-butane |
| GHS03 | flame over circle | oxidising substances – may cause or intensify fire | concentrated hydrogen peroxide, ammonium nitrate, potassium permanganate |
| GHS04 | gas cylinder | gases under pressure – compressed, liquefied, refrigerated liquefied, dissolved | oxygen, nitrogen, CO₂, acetylene in cylinders |
| GHS05 | corrosion | corrosive to skin and eyes, corrosive to metals | sulfuric acid, hydrochloric acid, sodium hydroxide |
| GHS06 | skull and crossbones | acute toxicity (categories 1–3) – fatal or toxic | cyanides, methanol, nicotine, chlorine |
| GHS07 | exclamation mark | harmful, irritant, skin sensitising, narcotic effects; hazardous to the ozone layer | many detergents, laundry capsules, diluted acetic acid |
| GHS08 | human silhouette with a “star” on the chest | carcinogenicity, mutagenicity, reproductive toxicity, respiratory sensitisation, aspiration hazard | benzene, formaldehyde, petrol, turpentine |
| GHS09 | dead tree and fish | hazardous to the aquatic environment | sodium hypochlorite, copper sulfate, mercury, some pesticides |
GHS01 – explosive
The exploding bomb symbol indicates substances that may explode as a result of impact, friction, a spark or heating. It covers explosives, pyrotechnic mixtures, self-reactive substances and some organic peroxides. Examples: nitroglycerine, trinitrotoluene (TNT), black powder. Such substances are subject to special rules on storage and trade.
GHS03 – oxidising substance
The flame over circle indicates oxidising substances, which need not be flammable themselves but supply oxygen and may cause a fire or greatly intensify it on contact with combustible materials. Examples: concentrated hydrogen peroxide, ammonium nitrate, sodium nitrate, potassium permanganate, sodium chlorate. We discuss them in detail in a separate section below.
GHS02 – flammable substance
The flame is one of the most common pictograms. It indicates flammable gases, aerosols, liquids and solids, as well as pyrophoric substances (which ignite spontaneously in air), self-heating substances and substances which emit flammable gases on contact with water. Examples: petrol, ethanol, acetone, propane-butane, solvents, aerosols.
GHS04 – gas under pressure
The gas cylinder indicates compressed, liquefied, dissolved and refrigerated liquefied gases. The hazard is the cylinder exploding if heated and, in the case of refrigerated gases, cryogenic burns. Examples: compressed oxygen and nitrogen, carbon dioxide, acetylene, liquid nitrogen. This pictogram says nothing about the toxicity or flammability of the gas – those hazards are indicated by additional pictograms.
GHS06 – toxic substance
The skull and crossbones indicates acute toxicity in the highest categories: the substance may be fatal or toxic if swallowed, in contact with skin or if inhaled, even in small amounts. Examples: potassium cyanide, arsenic compounds, methanol, nicotine, chlorine (gas).
GHS07 – harmful and irritant substance (exclamation mark)
The exclamation mark covers less severe hazards: harmful if swallowed, inhaled or in contact with skin, skin and eye irritation, skin sensitisation, respiratory irritation or narcotic effects (drowsiness, dizziness), and harm to the ozone layer. You will find it on many detergents, laundry capsules and washing-up liquids.
GHS05 – corrosive substance
The symbol showing a liquid eating away at a hand and a piece of metal indicates substances that cause severe skin burns, serious eye damage or are corrosive to metals. Examples: sulfuric acid, hydrochloric acid, sodium hydroxide (caustic soda), drain cleaners and some descalers.
GHS08 – serious health hazard
The human silhouette with a “star” on the chest indicates long-term hazards: carcinogenicity, mutagenicity, reproductive toxicity, respiratory sensitisation, specific target organ toxicity and aspiration hazard (liquid entering the airways, e.g. petrol or lamp oil). Examples: benzene, formaldehyde, petrol, turpentine.
GHS09 – substance hazardous to the environment
The dead tree and fish indicate substances that are toxic to aquatic organisms – acutely or with long-lasting effects. Such products must not be poured down the drain or onto the ground. Examples: sodium hypochlorite (bleaches), copper sulfate, mercury, many pesticides.
What is an oxidising substance?
An oxidising substance (oxidiser) is a compound that readily gives up oxygen or accepts electrons in chemical reactions. It usually does not burn itself, but it sustains and accelerates the combustion of other materials – even without access to air. This is why an oxidiser in contact with wood, paper, oil, fabrics or organic powders can cause a fire or a violent reaction.
Oxidising substances are marked with the GHS03 – flame over circle pictogram, and the label carries statements H270–H272 (e.g. H272 “May intensify fire; oxidiser”). It should not be confused with the GHS02 pictogram (flame alone), which indicates flammable substances.
Examples of oxidising substances:
- concentrated hydrogen peroxide (perhydrol),
- nitrates: ammonium, sodium, potassium – used among other things in fertilisers,
- potassium permanganate,
- chlorates and perchlorates, e.g. sodium chlorate,
- peroxides and persulfates, e.g. sodium persulfate,
- oxygen and nitrous oxide in cylinders (oxidising gases).
Oxidising substances are stored away from combustible materials, reducing agents, acids and sources of heat, in tightly closed, labelled containers. Spilled oxidisers are cleaned up without using sawdust or paper.
What do the signal words “Danger” and “Warning” and the H and P statements mean?
The pictogram is only part of the label. Under CLP, the labelling of a hazardous substance also includes:
- a signal word – “Danger” for more severe hazards or “Warning” for less severe ones,
- H statements (hazard statements) – describe the nature of the hazard, e.g. H225 “Highly flammable liquid and vapour”, H314 “Causes severe skin burns and eye damage”, H400 “Very toxic to aquatic life”,
- P statements (precautionary statements) – set out precautionary measures, e.g. P280 “Wear protective gloves/protective clothing/eye protection/face protection”, P305+P351+P338 on rinsing the eyes,
- the name of the substance or mixture, the supplier’s details and the nominal quantity.
H codes in the 200 series relate to physical hazards, those in the 300 series to health hazards, and those in the 400 series to environmental hazards. This means the type of hazard can be read even without knowing the language of the label.
How do the new pictograms differ from the old orange symbols?
Before CLP was introduced, Europe used black symbols on orange squares, marked with letters. CLP labelling has been mandatory for substances since December 2010 and for mixtures since 1 June 2015 (products with old labels could be sold until June 2017).
| Old symbol | Meaning | Current GHS/CLP pictogram |
|---|---|---|
| E | explosive | GHS01 |
| O | oxidising | GHS03 |
| F, F+ | highly and extremely flammable | GHS02 |
| T, T+ | toxic, very toxic | GHS06, or GHS08 for long-term effects |
| Xn | harmful | GHS07 or GHS08 |
| Xi | irritant | GHS07, or GHS05 for serious eye damage |
| C | corrosive | GHS05 |
| N | dangerous for the environment | GHS09 |
New in the GHS are the pictogram for gases under pressure (GHS04) and the separation of long-term hazards (GHS08) from acute toxicity (GHS06).
How do CLP pictograms differ from ADR transport labelling?
CLP pictograms inform the user about hazards during the use and storage of a product. Road transport, on the other hand, is governed by the ADR regulations, which require different warning labels: coloured diamonds showing the dangerous goods class number (e.g. class 3 – flammable liquids, class 8 – corrosive substances) and the UN number.
The two systems use similar symbols but are not interchangeable. An outer package may carry both CLP pictograms and ADR labels at the same time. For example, concentrated sulfuric acid bears the GHS05 pictogram on its label, and in transport a class 8 label and UN number 1830 – you can read more about this in the article How does sulfuric acid work: production, applications and safety measures.
Where do you come across chemical hazard pictograms in everyday life?
Pictograms are found not only in laboratories and industrial plants, but also on many household products:
- chlorine bleaches and disinfectants – GHS05 and GHS09 (more in our article on sodium hypochlorite),
- drain cleaners and descalers – GHS05,
- washing-up liquids, laundry capsules – GHS07,
- aerosols, solvents, firelighters – GHS02, often also GHS07 or GHS08,
- fertilisers and plant protection products – including GHS03, GHS07 and GHS09,
- gas cylinders – GHS04 and GHS02.
The packaging of some hazardous consumer products also has child-resistant fastenings and a tactile warning triangle for blind and partially sighted people. Chemical hazard pictograms are also one of the topics covered in chemistry lessons at school.
Who is responsible for labelling and what is a safety data sheet?
The supplier – the manufacturer, importer or distributor placing the product on the market – is responsible for classifying and labelling the substance. Based on the substance’s properties, the supplier assigns hazard classes, pictograms, the signal word and the H and P statements.
The supplier provides professional customers with a safety data sheet (SDS), as required by the REACH Regulation. It consists of 16 sections and covers, among other things, hazard identification, first-aid measures, fire-fighting and accidental release measures, storage, personal protective equipment and transport information. Employers are obliged to give employees access to safety data sheets and to train them in the safe handling of chemicals.
How can you work safely with substances marked with pictograms?
A few basic rules help to reduce the risk:
- read the label and the safety data sheet before use,
- use the protective measures indicated in the P statements – gloves, goggles, protective clothing, respiratory protection,
- store chemicals in their original, labelled containers and never decant them into drinks bottles,
- segregate incompatible substances – e.g. oxidisers away from combustible materials, acids away from alkalis and chlorine bleaches,
- ensure ventilation and access to water for rinsing the eyes and skin,
- do not pour substances bearing the GHS09 pictogram down the drain; hand in used chemicals for disposal.
Foodcom supplies industrial chemicals, including sulfuric acid, sodium hydroxide and sodium nitrate, always with safety data sheets and CLP-compliant labelling. For specifications and availability, please contact our sales team.
