GHS hazard pictograms

The nine pictograms

Exploding bomb: explosive. Explosive, self-reactive and some organic peroxide hazards. In a school or lab, picric acid is the chemical most associated with this hazard, although wetted stock may carry the flame symbol instead. Treat any such stock as a priority for specialist advice. If it may have dried out, do not move it.

Flame: flammable. Flammable gases, liquids, solids and aerosols, plus certain peroxides and reactive or self-heating substances. Some substances under this symbol release flammable gas when in contact with water, and sodium metal is an example. Flammable solvents belong in a suitable fire-resisting cabinet or store, away from oxidisers. Water-reactive stock such as sodium metal needs storage suited to that reaction.

Flame over circle: oxidising. Oxidising gases, liquids and solids. These can start or intensify a fire by supplying oxygen, even where nothing looks flammable. Potassium permanganate and sodium chlorate are examples. Keep them away from flammable and organic material. A flame and a flame over a circle look alike at a glance and call for quite different storage.

Gas cylinder: gas under pressure. Gases held under pressure, in cylinders and other containers. In labs this usually means compressed or liquefied gas cylinders, which need securing and need ventilated storage. Waste cylinders are quoted by enquiry, not online.

Corrosion: corrosive. Severe skin burns and eye damage, or serious eye damage alone. Concentrated acids and alkalis are the examples everyone knows, but HSE notes that some cleaning products carry this symbol because of the eye damage they can cause. It may also be used for substances corrosive to metals. Keep these low on the shelf, and use eye protection every time.

Skull and crossbones: acute toxicity. Severe acute toxicity, where a small amount can kill or seriously harm you by swallowing, skin contact or breathing it in. Keep such substances locked away.

Exclamation mark: health hazard. Less severe acute toxicity, skin irritation and serious eye irritation. HSE lists this symbol as health hazard and hazardous to the ozone layer. It appears on many ordinary lab and cleaning products. It is the mildest of the health symbols, and it still calls for reading the statements.

Health hazard: serious health hazard. The head and shoulders with a star. Respiratory sensitisers, mutagens, carcinogens, reproductive toxins, serious organ toxicity and aspiration hazards. This symbol is easy to underrate because effects may be long-term and nothing seems to happen on the day. Formaldehyde, xylene and many solvents carry it. Take the fume cupboard and exposure questions seriously for anything that has it.

Environment: hazardous to the environment. The dead tree and fish, for harm to the environment, including aquatic life. Mercury and silver compounds are examples. This is one more reason nothing should go down the sink as a matter of routine.

Signal words

GB CLP uses two signal words. Danger is shown for more severe hazards and Warning for less severe ones. Only one appears on a label, and it is chosen according to the most severe hazard. A label showing Danger for a chemical you considered ordinary is worth a second look.

Hazard and precautionary statements

A hazard statement describes the nature of the hazard. Each has a code beginning with H, such as H318, which reads "Causes serious eye damage". H2 codes are physical hazards, H3 codes health hazards and H4 codes environmental hazards.

A precautionary statement gives recommended measures to minimise or prevent harm. Each has a code beginning with P, such as those telling you to wear eye protection. HSE says suppliers usually select no more than six. P2 codes generally deal with prevention, P3 with response, P4 with storage and P5 with disposal.

The H statements are what you most need for a risk assessment. The pictogram draws your attention to the hazard, and the statement tells you what it is. For example, HSE explains that a product labelled H318 carries the corrosive pictogram and one labelled H319 (causes serious eye irritation) carries the exclamation mark.

Reading a label in a prep room

Take a sound, labelled bottle from the shelf. Read the name and concentration first. Then look at the signal word, the pictograms and the H statements together. Finally, look at any date written on it. For anything unfamiliar, the supplier's safety data sheet has far more detail.

Concentration changes the picture. A concentrated stock solution and a bench dilution of the same chemical may carry quite different labels. If you make up a dilution, it needs its own correct label, and that label should reflect the hazard at that strength.

Pictograms and storage

Pictograms offer useful hints on where a bottle belongs, but they are not a storage plan on their own. A chemical may carry several pictograms, and some storage issues never show up on the label at all. Peroxide formation in old ether is an example. Our chemical storage classes guide explains how to turn hazards into an arrangement for your shelves.

Old labels

Older stock may show the former orange-square symbols instead of the red diamonds. Those bottles are not exempt from anything, and the label is often a useful sign that the stock has been around for a long time. Check its condition, and consider whether you still need it. If you are in any doubt about what is in it or whether it is stable, do not open it. See expired and unlabelled chemical disposal.

Pictograms on our site and in the register

Every page in our chemical database shows the chemical's pictograms, signal word, and H and P codes, with the source and retrieval date. In the Chemical Register that data appears on each container, and it can print GHS container labels. These are guidance only: check your own risk assessment and your supplier's safety data sheet.