How to Use Chemical Safety Signs, Pictograms and Charts for Hazard Identification

One picture can speak a thousand words, which seems to be true when it comes to hazard identification and communication. Pictures, or rather hazard pictograms, which are used for the labelling of chemicals, are meant to convey a clear message about potential dangers and hazards of the labelled chemical product across the language barriers and help the user stay safe while handling the chemical by informing them about the risks and risk preventive measures.

What are the hazard pictograms, and why do we use them?

Hazard pictograms are used to alert the presence of a hazardous chemical. The pictograms should help us know which chemicals we are using might be dangerous and can cause harm to people or the environment. Globally Harmonized System (GHS) for classifying and labelling chemicals prescribes nine different pictograms. The GHS hazard pictograms appear in the shape of a diamond with a distinctive red border and white background. Due to the GHS regulation implementation around the globe, these are now considered almost universal and applicable in most markets and countries worldwide. 

The pictograms are used to describe specific hazards associated with the chemicals. It is not unusual to have more than one pictogram appearing on the labelling of a single chemical. The table below shows all GHS hazard pictograms with a short description and the associated hazards.

Table 1. GHS hazard pictograms

Pictogram symbol

Pictogram code

Associated hazards

General explanation

GHS01

Explosive (Symbol: exploding bomb)

  • Unstable explosives
  • Explosives
  • Self-reactive substances and mixtures (Types A, B)
  • Organic peroxides (Types A, B)

Chemicals that can cause explosions.

GHS02

Flammable (Symbol: flame)

  • Flammable gases, aerosols, liquids and flammable solids
  • Self-reactive substances and mixtures (Types B, C, D, E, F)
  • Pyrophoric liquids and solids
  • Self-heating substances and mixtures
  • Substances and mixtures, which in contact with water, emit flammable gases
  • Organic peroxides (Types B, C, D, E, F)

Chemicals that can burn or can release gases that burn.

GHS03

Oxidising (Symbol: flame over circle)

  • Oxidising gases, liquids and solids

Chemicals that give off oxygen and can make a fire spread.

GHS04

Gas under pressure (Symbol: gas cylinder)

  • Gases under pressure
  • Compressed gases
  • Liquefied gases
  • Refrigerated liquefied gases
  • Dissolved gases

Gases or liquids which are under pressure and for that reason can explode.

GHS05

Corrosive (Symbol: corrosion)

  • Corrosive to metals, skin or eyes (severe eye damage)

Chemicals that cause permanent damage to skin or eyes are corrosive to metals.

GHS06

Acute toxicity (Symbol: skull and crossbones)

  • Acute toxicity (oral, dermal, inhalation) – categories 1-3

Poisonous chemicals can quickly cause severe sickness or even death. These toxins attack one or more body parts/organs. Considered toxic or fatal.

GHS07

Health hazard/ Hazardous to the ozone layer (Symbol: exclamation mark)

  • Acute toxicity (oral, dermal, inhalation) -hazard category 4
  • Skin irritation
  • Eye irritation
  • Skin sensitisation,
  • Specific Target Organ Toxicity — Single exposure - hazard category 3
  • Respiratory tract irritation
  • Narcotic effects

Chemicals which can cause health issues, which usually do not lead to severe illnesses or death. Pictograms might also be used for chemicals that destroy the ozone layer.

GHS08

Serious health hazard (Symbol: health hazard)

  • Respiratory sensitisation
  • Germ cell mutagenicity
  • Carcinogenicity
  • Reproductive toxicity
  • Specific Target Organ Toxicity — Single exposure - hazard categories 1, 2
  • Specific Target Organ Toxicity — Repeated exposure - hazard categories 1, 2
  • Aspiration hazard

Chemicals can cause serious health issues or illnesses. Effects can be immediate or delayed.

GHS09

Hazardous to the environment (Symbol: environment)

  • Hazardous to the aquatic environment

Chemicals dangerous for the environment. These chemicals should not enter waterways or soil.

The GHS hazard pictograms are primarily used for the labelling of the containers for the consumers and at the workplace. While they can be used in transport, the second set of pictograms is usually used to transport dangerous goods. Transport pictograms are used in a wider variety of colours and may contain additional information such as a subcategory number.

Table 2. Transport of the dangerous goods hazard pictograms

Pictogram

Class 

Associated hazards

1 - Explosives

Division 1.1 - Substances and articles which have a mass explosion hazard

Division 1.2 - Substances and articles which have a projection hazard but not a mass explosion hazard

Division 1.3 - Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard


Note: The asterisks are replaced by the class number and compatibility code

1 - Explosives

Division 1.4 - Substances and articles which are classified as explosives but which present no significant hazard


Note: The asterisk is replaced by the compatibility code

1 - Explosives

Division 1.5 - Very insensitive substances which have a mass explosion hazard


Note: The compatibility code replaces the asterisk

1 - Explosives

Division 1.6 – No hazard statement


Note: The compatibility code replaces the asterisk

2 - Gases

Division 2.1: Flammable gases – Gases which at 20 °C and a standard pressure of 101.3 kPa:

  • are ignitable when in a mixture of no more than 13 % by volume with air; or
  • have a flammable range with air of at least 12 percentage points regardless of the lower flammable limit.

(alternative pictogram)

2 - Gases

Division 2.2: Non-flammable, non-toxic gases – Gases which:

  • are asphyxiant – gases which dilute or replace the oxygen normally in the atmosphere; or
  • are oxidising – gases which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does; or
  • do not come under the other divisions.

(alternative pictogram)

2 - Gases

Division 2.3: Toxic gases – Gases which:

  •  
  • are known to be so toxic or corrosive to humans as to pose a hazard to health; or
  • are presumed to be toxic or corrosive to humans because they have an LC50 value equal to or less than 5000 ml/m3 (ppm).

3 – Flammable liquids

Flammable liquids – Liquids that have a flashpoint of less than 60 °C and which are capable of sustaining combustion


(alternative pictogram)

4 – Flammable solids

Division 4.1: Flammable solids, self-reactive substances and solid desensitised explosives – Solids which, under conditions encountered in transport, are readily combustible or may cause or contribute to fire through friction; self-reactive substances which are liable to undergo a strongly exothermic reaction; solid desensitised explosives which may explode if not diluted sufficiently

4 – Flammable solids

Division 4.2: Substances liable to spontaneous combustion – Substances which are liable to spontaneous heating under normal conditions encountered in transport, or to heating up in contact with air, and being then liable to catch fire

4 – Flammable solids

Division 4.3: Substances in contact with water emit flammable gases – Substances which, by interaction with water, are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities

(alternative pictogram)

5 -Oxidizing substances

Division 5.1: Oxidizing substances – Substances which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to the combustion of other material

5 -Oxidizing substances

Division 5.2: Organic peroxides – Organic substances which are considered derivatives of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals

(alternative pictogram)

6 – Toxic substances

Division 6.1: Toxic substances – substances liable either to cause death, serious injury or to harm human health  if swallowed, inhaled or by skin contact;

6 - Infectious substances

Division 6.2: Infectious substances -

substances known or reasonably expected to contain pathogens. Pathogens are 

defined as microorganisms (including bacteria, viruses, rickettsiae, parasites, fungi) and 

other agents such as prions can cause disease in humans or animals.


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

7 - Radioactive material

Radioactive material means any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed the values specified in the regulation – LSA I (low specific activity 1)


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

7 - Radioactive material

Radioactive material means any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed the values specified in the regulation – LSA II (low specific activity 2)


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

7 - Radioactive material

Radioactive material means any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed the values specified in the regulation – LSA III (low specific activity 3)


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

7 - Radioactive material

Fissile material means uranium-233, uranium-235, plutonium-239, plutonium-241, or any combination of these radionuclides.


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

8 – Corrosive substances

Corrosive substances – Substances which:

  •  
  • cause full thickness destruction of intact skin tissue on the exposure time of fewer than 4 hours; or
  • exhibit a corrosion rate of more than 6.25 mm per year on either steel or aluminium surfaces at 55 °C

9 - Miscellaneous dangerous substances and articles

Miscellaneous dangerous substances and articles - are substances and articles that present a danger not covered by other classes during transport. Includes:


  • environmentally hazardous substances not covered by other classes;
  • elevated temperature substances (substances transported or offered for transport at temperatures equal to or exceeding 100 °C in a liquid state or at temperatures equal or exceeding 240 °C in a solid-state); 
  • GMMOs (Genetically modified microorganisms) or GMOs (genetically modified organisms) do not meet the definition of infectious substances. Still, they can alter animals, plants or microbiological substances in a way not normally the result of natural reproduction. 


Note: Class and pictogram included in the UN Model Regulations but have not been incorporated into the GHS

GMMOs or GMOs are not subject to these Regulations when authorised for use by the competent authorities of the Governments of the countries of origin, transit and destination.

Other chemical safety symbols

Besides the hazard pictograms, other chemical safety signs and symbols are commonly used in the HSE world. These can be divided into four standardised categories – 

  • prohibition, 
  • warning, 
  • mandatory, and 
  • emergency. 

Each category can be recognised by its colour and shape (see table 3). The purpose of these symbols is to instruct the workers to stop the operation, take precautions, move or select the proper personal protective equipment. The following table shows the four categories associated with colours, features, associated instructions, and examples.

Table 3. Other chemical safety signs and symbols

Category

Colour and features

Associated instructions

Pictogram example

Prohibition 

Red circle crossed out frame with black symbol and white background

‘’do not’’;

Stop the operation;

Evacuate;

Prohibited access;

No open flame

Warning

Yellow triangular shape with black frame and black symbol and yellow background

Take precautions

Electricity hazard

Mandatory

Blue round shape with white symbol and blue background

Use this

Complete the action

Wear protective gloves

Emergency

Green or red rectangle or square shape with white symbol and green/red background

First aid or emergency measures

Eye wash station

Fire extinguisher

A single area usually contains more than one sign. Production hall will, for example, have multiple pictograms showing the mandatory personal protective equipment that needs to be used at the workplace and signs on where the first aid kit is located, or fire extinguisher or emergency alarm button can be found. Prohibition signs could also be found, labelling the area where it is restricted or prohibited to eat and drink or smoke. Warning symbols could also be attached for high voltage machinery or a possibility for slipping hazards. All of these can be located in one area or facility if needed.

These symbols are usually used on workplace instructions (WPI) or safety sheets. WPI’s or safety sheets are one- or two-page documents prepared by the HSE personnel to inform the workers about the risks and safety measures associated with using hazardous products. Some countries have implemented the WPI preparation and use at the workplace. WPI’s usually contain information derived from the SDS’ and exposure scenarios but modified to suit the local handling needs. These simplified documents typically contain the following information:

  1. Chemical identification and hazard information

  2. First aid and safety measures

  3. Emergency measures in case of fire

  4. Accidental release measures and information about disposal

  5. Local information (e.g. local emergency numbers, responsible persons info, department information)

If your country has not implemented WPI requirements in their chemical legislation framework, they are probably not prohibiting their use either. This is why, in a joint project, the World Health Organisation (WHO), International Labour Organisation (ILO) and European Commission (EC) have joined hands and formed a collection of over 1700 documents identifying chemical hazards and called them International Chemical Safety Cards (ICSC’s). The ICSC’s are available in the database in 12 different languages: English, French, Spanish, Russian, Chinese, Italian, Japanese, Finnish, Hungarian, Polish, Hebrew, Korean and Persian. All of the documents are being reviewed every two years.

An example of an International Chemical Safety Card. Source: International Labour Organization.

The information available in the ICSC includes:

  1. Identification of the chemical

  2. First aid

  3. Fire and explosion hazards

  4. Preventative measures

  5. Classification and labelling

  6. Firefighting measures

  7. Physical and chemical properties and dangers

  8. Environmental data

  9. Long- and short-term health effects

  10. Storage, packaging and spillage disposal

  11. Acute health hazards and prevention

  12. Regulatory information and occupational exposure limits.

ICSC provides enough information at a glance for a worker who is not familiar with the technicality of the SDS’ to access and use safety information necessary for safe handling of the chemical. Similarly to WPI’s, ICSC documents are also prepared based on the information available in the SDS’. Being the simplified version of the SDS’, ICSC’s are usually used to transpose the SDS information for direct use at the workplace. ICSC’s can’t be used as a substitute for the SDS’ as they do not entirely follow the regulatory requirements according to the SDS’ are prepared. 

Even though hazard pictograms and safety symbols, and cards are internationally used, there may still be some local differences that need to be considered. Please be always advised to check and follow local requirements to stay compliant at the workplace.

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