What is chemical hazard? Types, Chemical hazard symbols and examples

We explain to you what the chemical hazard is, in what circumstances it is higher, what types of chemical hazard that are exist and the characteristics of each one.

What is chemical hazard?

In chemistry , chemical risk or chemical hazard is understood as those conditions of potential damage to health caused by uncontrolled exposure to chemical agents of various kinds. In other words, it is about the danger posed by chemical compounds  and chemical substances , capable of causing diseases, chronic effects or death.

The severity of these risks depends on factors such as the nature of the chemical agents, their concentration, or the time and route of exposure to them.

It is not exaggerated, however, if it is claimed that virtually every reactive chemical has a potential for change in the nature ( chemical contamination ) or in the organism of a living being , only that some will be more harmful in the short term and others will be, on the contrary, less immediate.

There is a potential chemical risk in jobs that involve the management of toxic substances , or in those that are underproduced and not properly managed, or in which personnel lack the minimum basic protections.

However, there is also a chemical risk in nature itself, since the dumping of chemical substances into the environment takes place in alarming daily proportions. And not always nature can deal with them effectively and autonomously.

  1. Types of chemical hazard

chemical risk types laboratory protection
Laboratories have protection against various forms of chemical risk.

The chemical risks can be diverse, depending on the effect they may have on living beings, particularly the human being. So, we talk about:

  • Flammable . Substances that react easily with the environment or with themselves after the injection of some energy , releasing very high amounts of heat , that is, caloric energy. Generally this is accompanied by the creation of flames, that is, of fire, capable of spreading to other materials.
  • Extremely flammable: Liquid substances and preparations, whose flash point is between 21 ° C and 55 ° C. For example: hydrogen, ethyne, ethyl ether, etc. Caution: avoid contact with ignitive materials (air, water).
  • Explosives . Materials that react quickly and violently to combustion, generating huge amounts of heat, light and kinetic energy ( movement ), either in a controlled and usable way, or uncontrolled and catastrophic.
  • Oxidizing . Substances capable of generatingviolent oxidation in flammable substances, that is, that can trigger fire or delay its extinction.
  • Corrosives . Those compounds endowed with a great capacity of oxide-reduction before organic matter , generating an exothermic and highly destructive reaction, capable of producing burns without the need for flame. Corrosive materials can oxidize metal or destroy organic tissues by contact.
  • Irritants . A lighter version of corrosives, capable of producing reversible lesions on human skin or mucous membranes, but not completely destroyed.
  • Toxic . These compounds have molecular properties that make them highly reactive with the organism , thus causing unpredictable effects on it.
  • Very toxic: By inhalation, ingestion or absorption through the skin, it causes serious health problems and even death. For example: Cyanide, Arsenium Trioxide, Nicotine, etc. Caution: all contact with the human body must be avoidable.
  • Radioactive: . These are atomically unstable substances, whose molecules emit particles (neutrons, protons, etc.) constantly as they decompose into another stable element. The emission of these particles can alter the genetic code and damage the tissues.
  • Dangerous for the environment: The contact of this substance with the environment can cause damage to the ecosystem in the short or long term. Precautions: Due to its potential risk, it should not be released into the pipes, the ground or the environment. Special treatments have to be taken.These substances are represented by symbols of universal recognition, which are called pictograms, which are represented in black characters on a yellow background, except for the one representing harmful or irritating substances, which are represented on orange backgrounds to avoid confusion with traffic signs. .

Types of hazardous chemicals

The material form of a hazardous chemical can influence how it enters the body and to some extent the damage it causes. The main material forms of hazardous chemicals are solids, powders, liquids, vapors, and gases.


Solids are the forms of dangerous chemicals that are likely to cause chemical poisoning, although some can cause poisoning if they touch the skin or get into food when ingested. Hazardous chemicals in solid form can give off toxic fumes that can be inhaled, and solids can be flammable and explosive, as well as corrosive to the skin.

Metallic fumes

They are solid particles that are generated from molten condensation.


Powders are small particles of solids. The main danger from hazardous dusts is that they can be breathed in and get into the lungs. The smallest particles are the most dangerous because they can enter the lungs and have harmful effects, or they can be absorbed into the bloodstream and pass to parts of the body, or they can cause injury to the eyes. Under certain conditions, dusts can explode, for example in grain silos or flour mills.


Many liquid chemicals are dangerous as they give off vapors that can be inhaled and can be highly toxic, depending on the substance. Some products can immediately damage the skin and others pass directly through the skin into the bloodstream so they can travel to different parts of the body. Moisture and vapors are often invisible.


Many liquid chemicals evaporate at room temperature, which means they form a vapor and remain in the air. The vapors of some chemicals can irritate the eyes and skin, and inhalation can have serious health consequences. Vapors may be flammable or explosive.


Gaseous substance at a temperature of 20 ° C and a pressure of 101.3 kPa (1 atm). Some gases may have harmful (toxic, corrosive …) or dangerous (flammable, explosive …) properties. Detecting its presence by odor is misleading: Many gases and vapors have their toxicity threshold below the odor threshold.

Activities in which it is exposed to chemical hazard

  • Teaching and research activity in laboratories.
  • Welding tasks.
  • Degreasing operations.
  • Foundry operations.
  • Distillations, rectifications and extractions.
  • Cleaning with chemicals.

Effects of chemical hazard

  • Corrosion: They produce partial or total destruction of the tissues with which it contacts (skin, eyes and digestive system are the most affected parts).
  • Irritation: Irritants cause inflammation of the tissues with which they come into contact.
  • Allergic reactions: They can be dermatological or respiratory, causing pictures of itching, rhinitis, contact dermatitis, etc.
  • Pneumoconiotics: They produce chronic pulmonary alteration by prolonged inhalation of particles.
  • Asphyxia: Asphyxiants exert their effect by preventing the transfer of oxygen to the tissues.
  • Anesthetics and Narcotics: They act as central nervous system depressants causing dizziness, nausea, etc., normally reversible (industrial solvents).
  • Cancer: Known human carcinogens are substances that act by interfering with the reproductive or sexual functions of the person.
  • Systemic toxics: They are the agents that cause injury to certain organs or specific systems of the body such as the brain, liver, kidney, lung, etc.

Symbols of Chemical hazard

Corrosive Chemical hazard symbols

Corrosive chemical hazard

Definition: These chemicals cause destruction of living tissues and / or inert materials.

Caution: Do not inhale and avoid contact with skin, eyes and clothing.


  • Hydrochloric acid
  • Hydrofluoric acid
  • Potassium hydroxide
  • Sulfuric acid

Explosive Chemical hazard symbols Explosive chemical hazard

Definition: Substances and preparations that can explode under the effect of a flame or that are more sensitive to shocks or frictions than dinitrobenzene .

Caution: Avoid bumps, shocks, friction, flames or sources of heat.


  • Nitroglycerine
  • fluorine

Oxidizing Chemical hazard symbols Oxidizing chemical hazard

Definition: Substances that have the ability to ignite other substances, facilitating combustion and preventing fire fighting.

Caution: Avoid contact with combustible materials.


  • Oxygen
  • Potassium nitrate
  • Hydrogen peroxide


Definition: Substances and preparations that can be heated and finally ignited in contact with air at a normal temperature without the need for energy, or that can be easily ignited by a brief action of a source of ignition and that continue to burn or burn after having removed the source of ignition, or flammable in contact with air at normal pressure, or that, in contact with water or humid air, emit easily flammable gases in dangerous quantities.

Caution: Avoid contact with ignitive materials (air, water).


  • Hydrogen
  • Ethyne
  • Ethyl ether
  • Ethanol
  • Acetone

Gas Chemical symbols Gas

Classification : Compressed, liquid or dissolved gaseous substances, contained at pressure of 200 kPa or higher, in a container that can explode on heat.

Caution : Never throw them into fire


  • Pressurized gas bottles
  • Homemade insecticides
  • Home air fresheners

Skin irritation symbols Skin irritation

Classification : Substances and preparations that by skin penetration, may involve serious, acute or chronic health risks.

Caution : All contact with the human body should be avoided.


  • Ammonia
  • Bleach

Acute toxicity symbols Acute toxicity

Definition: Substances and preparations that by inhalation, ingestion or absorption through the skin, cause serious health problems and even death.

Caution: All contact with the human body should be avoided.


  • Cyanide
  • Arsenic trioxide
  • Methanol

Dangerous by aspiration Chemical hazard symbols Dangerous by aspiration

Definition: Substances and preparations which, by inhalation, ingestion or skin penetration, may pose serious or acute health risks.

Caution: Contact with the human body, as well as inhalation of vapors, should be avoided


  • Methanol
  • Carbon monoxide
  • Chlorine

Dangerous for the environment Chemical hazard symbols Dangerous for the environment

Definition: The contact of this substance with the environment can cause damage to the ecosystem in the short or long term.

Handling: Due to its potential risk, it should not be released into the pipes, the ground or the environment.


  • Benzene
  • Potassium cyanide
  • Lindane

Norms to reduce the risk derived from storage

One way to control and reduce the risk associated with chemicals is stored in suitable conditions for which there exists a rules based on technical and legal aspects:

  • Take into account the dangerous characteristics of the products and their incompatibilities.
  • Keep the stored quantity to an operating minimum.
  • Group and / or separate for chemical compatibility.
  • Isolate or confine those with special characteristics.
  • Check the labeling, condition of the containers, exterior cleanliness …
  • Keep an updated record of stored products.
  • Use security cabinets.

The accumulation of chemicals in storage places creates risks that can and should be eliminated or reduced. In this regard, it is necessary to distinguish industrial facilities with high volumes of substances from other places with limited storage capacity (laboratories, hospitals …).

In the case of industrial premises, storage facilities must comply with European and Spanish standards.  These include storage guidelines, called “Supplemental Technical Instructions” or ITCs for some specific compounds. It is worth highlighting the obligation to register in a Register of Industrial Establishments when the quantity of stored product exceeds certain limits.

In the case of places with limited storage capacity (laboratories, hospitals …) a series of basic work rules are recommended.

Managing the risks of chemical warehouses involves following minimum management measures:

  • -Adequate storage space: Passage areas must be marked and free of obstacles and the maximum stacking height is limited.
  • -Stored product management system: In addition to having inventory control, it is recommended to reduce the amount of stored product to the minimum admissible.
  • -Distribution of the products taking into account the incompatibilities between them.
  • -Measures to prevent accidents and emergencies: They include ventilation systems, spillage retention buckets, showers and eyewashes, alarm systems, protective equipment …

An important aspect to consider is the ability of some chemicals to react with each other, so the risk of an uncontrolled reaction must be prevented. For this, chemicals are usually separated based on their reactivity.

The basic incompatibilities are:

  • Acid-base
  • Oxidizer-reducer
  • Water-alkali metals
  • Air-pyrophoric materials

To this is added the convenience of separating toxic products from flammable and explosive products, so that the incompatibility table can be expanded with a more detailed classification of the types of incompatible substances.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Back to top button