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Chemical Hazard Symbols and Signs and Their Meanings: A Detailed Guide

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Susan is a science geek and writer who loves writing articles and tutorials to help you out!



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Safety in the home, garage and laboratory is essential if you are a scientist, doing chemistry or even an everyday person with dangerous substances in the home and garage. There are many dangers lurking in the laboratory and home waiting to get at you. From chemicals to Bunsen burners you need to be extra careful. However, in schools especially, students are taught about chemicals, their dangers and how to prevent any accidents. However, even in the home and garage, dangerous chemicals could be lying there without your attention. Caustic Soda (lye) which is used in cleaning drains and the making of soap is extra-corrosive and will eat into your flesh should it come in contact with your skin. Moss killer which is used in garden patios is corrosive again. Luckily enough, there are hazard symbols on any products which are classified as harmful. This hub aims to explain all the different hazard symbols and what they mean.

Harmful or Irritant

Harmful or Irritant


This is marked with a black X on an orange background. A lot of products have this such as many weak acids or alkalis. If you get it on your skin, it will cause it to go red and blister. If you are using a product which is irritant, always wear eye goggles and gloves. Wash any spills on your skin.




The word corrosive derives from the Latin verb corrodere meaning 'to gnaw' Concentrated solutions of strong bases such as caustic soda are very corrosive. If this comes in contact with your skin, it will burn and eat away into your flesh. Corrosive substances are very dangerous and be extra careful when handling them! Always wear eye protection, a face shield and gloves. If corrosive substances come in contact with your eyes, it can cause permanent blindness. A drop of a corrosive on the eye may cause blindness within 2-10 seconds!They can come in any state of matter: solid, liquid or gas. A low concentration of corrosive substances are often referred to as 'irritant'.




These are substances that burn very vigorously when ignited at a relatively low temperature. Always handle with care near fire, heat or any other form of shock as they can ignite almost instantly, so do this to prevent any accidental fire.




Lead oxide is considered to be a toxic substance. Any ingestion or inhalation of a toxic substance can cause difficulties with respiratory and other systems, leading to death. You must take utmost care when handling these substances. Always wear a face shield, eye protection and gloves.




These substances do not burn themselves but produce oxygen for highly flammable substances to burn. If you are using an oxidising substance, it could cause your clothing to go on fire so wear eye protection and wear an anti-flammable lab coat.




It is uncommon to get a substance which is explosive in the household, but just in case you come across it in every day life, it is handy to know what the symbol looks like, as you can see on the right. An explosive material is extremely dangerous as it has a huge amount of potential energy of heat, light, sound and power to exert. You may know these substances more simply as 'bombs'. Substances with these symbols must be handled with utmost extreme care and it is advised to keep these substances away from heat, fire and other forms of shock as the substance can go under combustion very easily.

Danger! High voltage!

Danger! High voltage!

High Voltage

This sign means 'high voltage' and is a very good warning sign, too! The term high voltage means electricity at such a high voltage that if any living thing goes near it, it will cause harm or even death. If you see a sign like this at an industrial site, do not go anywhere near that area as the electricity is so high, it will kill or severely harm you.

This sign would be most likely used in industrial and scientific areas as certain equipment requires high voltage to function. You may also find this sign at electrical power distribution centres.

Biohazard, commonly used in hospital laboratories and scientific sites.

Biohazard, commonly used in hospital laboratories and scientific sites.


Biohazards, also known as biological hazards are microorganisms or biological substances that pose a threat to the health of a living organism. These hazards can include toxins, viruses, dangerous bacteria and contagious microorganisms. You would mainly find this sign in laboratories, biochemistry laboratories in hospitals and pharmaceutical sites as scientists working there would have to test viral samples and other bacteria which could pose a threat to the health of the workers there. This sign is also used on the labelling of products which may include hypodermic needles, samples and other substances. Extreme caution must be taken when using these substances and always wear a face mask and gloves. Consult a scientist working in the laboratory for more information on how to handle such products.

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Disposing needles and samples in a sharps container is standard procedure used by scientists. As you can see, the biohazard sign is labelled on this container.

Disposing needles and samples in a sharps container is standard procedure used by scientists. As you can see, the biohazard sign is labelled on this container.


Dangerous To The Environment

This symbol indicates a substance which can harm or kill any living things in the environment. This may include aquatic species in lakes getting killed because of dangerous substances being thrown around the area. Substances like these may include white spirits, which is used to clean paint from clothes.

If you come in contact with a substance like this, do not throw it away down the drain, into the ground, into a lake or any other natural habitat as it may kill or harm trees, plants, fish, animals and other living things. Always handle substances like this with extreme caution and always dispose carefully, in bins which allow toxic and dangerous substances to be thrown into. Consult your council for more information.


NEW: Hazardous To Life

This image shows that the chemical liquid or gas may cause problems for the organism including the respiratory, sensory and nervous systems. These substances are highly dangerous and life threatening! Do not come in contact with these substances and always consult a scientist for more information.

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Please Note...

The author of this text does not claim any responsibility for accidents that occur in the laboratory, always consult an expert for more information. All experiment are carried out at your own risk.


MB on January 18, 2020:

Really helped with my science homework.


izzy on September 11, 2017:

helped me with my homework lots

Peter on August 31, 2016:

Thanks! It helped me a lot about my homework! :)

sara on October 19, 2015:

this was good

Susan W (author) from The British Isles, Europe on June 26, 2015:

Thanks Catherine! Glad I could help!

catherine on June 26, 2015:

it was a big help thanks !

Jordan on January 15, 2015:

add a radioactive sign but make it secondary

jai on January 15, 2015:


Hello on November 14, 2014:

Nice information! Maybe give more examples of these symbols in everyday life. Thanks

bub on October 21, 2014:

this is actually very useful

Epic cheese on February 11, 2014:

needs more variety of signs other than radioactive based ones

Ashley on January 26, 2014:

this helped me

Kas on September 21, 2013:

Cool signs ur good

tae joon soo on September 10, 2013:

thanks for posting this....this will help me to prevent accidents.....

Mati on September 09, 2013:

Thank you very much for such a great sign

Awesome description ,

Thanks for solved my problem

Susan W (author) from The British Isles, Europe on April 24, 2013:

Thanks so much for the great comment! I'll be updating next week fo make sure to stop by!

Cuttler from HubPages on April 24, 2013:

Thanks for sharing this. I often confuse these warning signs and it's great that you decided to share this. Hope to see more of the signs. Nice hub

NISARG MEHTA from SURAT, Gujarat, India on April 13, 2013:

Sounds great!!! Will be waiting for more.. [Smiles]

Susan W (author) from The British Isles, Europe on April 13, 2013:

Thanks for the wonderful comments! Don't worry, I'll be updating this again so make sure to stay tuned! I've plans for a lot more signs and their details down the pipeline!

NISARG MEHTA from SURAT, Gujarat, India on April 12, 2013:

Nice hub. I will be waiting for more such signs and their details. Thanks for sharing. [Smiles]

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