Working safely with corrosive substances
The Control of Substances Hazardous to Health Regulations 2002 (COSHH) is the law that requires employers in the UK to control materials in work environments that can harm workers or visitors. Sometimes it is easy to identify dangerous materials, but people often take it for granted that everyday products, such as paint or bleach, are harmless. However, harmful substances can be:
- Chemicals
- Products containing chemicals
- Fumes
- Dust
- Vapours
- Mists
- Nanotechnology
- Different kinds of harmful gases, including asphyxiating gases
- Biological agents, such as pathogens used in laboratories
Many chemicals contain corrosive agents. These are especially harmful to human tissue and can potentially irritate and damage the:
- Eyes and skin through direct contact.
- Respiratory tract through the inhalation of corrosive vapours and mists.
- Gastrointestinal system through ingestion.
The HSE developed a guide to working with hazardous substances. It contains details on hazardous substances risk assessments and how employers should approach and customise COSHH provisions for their specific workplaces.
Types of corrosives and applicable safety protocols
Corrosives occur in all forms of matter. Employers must be aware of these different forms and the safety protocols to prevent injuries and fatalities.
Corrosive liquids
Corrosive liquids are things such as mineral acids, oxidising solutions or alkali solutions. Examples of highly corrosive liquids are bromine, sodium hydroxide, sulfuric acid and hydrogen peroxide. They are especially dangerous to the skin and eyes as splashes occur rapidly and without warning. Safety measures include:
- Wearing eye protection equipment in an area where workers handle corrosive liquids.
- Wearing gloves and other chemically-resistant PPE such as overcoats to form barriers between the skin and the harmful corrosive substances.
- Adding acids or bases to water to avoid flash steam explosions.
- Keeping acids and bases apart when storing them, and storing these items below eye level.
- Ensuring that emergency kits contain adequate supplies of spill control agents and specialised spill kits for specific corrosive substances.
Corrosive gases and vapours
Corrosive gases and vapours can cause both external and internal harm. Certain organs, such as the eyes and respiratory system, are particularly vulnerable to corrosive gases, mists and vapours. They dissolve in the body fluids and cause severe irritations to chemical burns. Substances with lower solubilities can enter deep into the lungs and cause respiratory distress. Examples of these include nitrogen dioxide, phosgene, sulfur dioxide and ammonia.
Eye, nose or respiratory tract irritations are not always a sure measure of exposure. Risk controls include:
- Wearing PPE such as chemical fume hoods and other respiratory protection. Cover all exposed skin areas.
- Securely closing regulators and valves when cylinders are not being used. Flushing with dry air or nitrogen may also be necessary.
- Preventing reverse flow when mixing gases and liquids.
Corrosive solids
Corrosive solids can burn the skin and eyes. Examples include sodium hydroxide, phenol, potassium hydroxide and sodium hydroxide. Some of these can cause significant heat when mixed with water. The dust released by these solids is also dangerous as it can be inhaled and damage the respiratory tract.
To prevent risks when handling corrosive solids, workers must:
- Wear PPE such as gloves and eye protection.
- Slowly add corrosive solids to water when mixing is required and apply cooling when needed.
- Wear fume hoods when handling generates lots of corrosive dust.
Storing and safe disposal of dangerous corrosive substances
Storing corrosive substances requires special cabinets specifically designed for this purpose. Some substances can be stored together, while others, such as acids and alkalis, must be stored separately. For example, you can safely store nitric acid with oxidisers, but organic acids must be separated from mineral acids.
Corrosive substance storage cabinets are non-metallic and have no internal metallic parts. They also have acid-resistant coatings and floors that can handle corrosive spills.
As corrosive substances are dangerous chemicals, they should be disposed of in terms of COSHH guidelines on chemical waste disposal. These disposal methods must not pose harm to humans or the environment.
Safety signs
It is essential to display the required safety signs in areas where exposure to corrosive substances is possible. Ordinarily, this warning signage must be combined with the compulsory signs of PPE required when entering an area or handling corrosive substances.
Employers must stay updated on legislative changes, which include new signage requirements, to ensure that their work environments comply with the safety regulations applicable to corrosive substances. These dangerous materials cannot be ignored and safety measures are not negotiable.
Take a look at our full range of COSHH safety products.