IOSH
Chemical safety essentials: what you should know
Guide to recognising and managing chemical hazards at work
Chemicals can be found in almost every type of workplace. Knowing how to spot them and handle them safely is vital for protecting people and meeting legal duties.
What are chemical hazards?
Chemical hazards are substances that have the potential to harm humans, other species or the environment (including the built environment of the workplace). Chemical hazards can be:
- naturally occurring – minerals like asbestos or gases like methane
- manufactured – such as cleaning products or an industrial chemical
- by-products – created during industrial processes, like welding fumes.
While many chemicals are useful and necessary, they may also be harmful and hazardous. Employers are responsible for managing the risks they present.
What kinds of chemicals are hazardous?
Hazardous chemicals can be grouped into categories based on the effects of the cause. Understanding chemical classifications will help you recognise the risks and required actions.
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Physical hazards
- Flammable or highly flammable – petrol, methylated spirits, liquefied petroleum gas (LPG)
- Explosive – ammunition, fireworks, certain industrial chemicals
- Oxidising – hair dyes, bleaches, and some cleaning products
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Health hazards
- Toxic – substances that interfere with normal body processes, causing illness (asbestos, lead, carbon monoxide)
- Harmful or irritant – cause inflammation or discomfort (many paints, adhesives, some cleaning products)
- Corrosive – destroys living tissue and can corrode surfaces (oven cleaners, caustic soda, strong acids)
- Sensitisers – substances that can cause allergic reactions, such as formaldehyde in nail care products, or preservatives and perfumes in soaps
- Carcinogenic – cancer-causing substances like silica dust, diesel fumes, asbestos
- Mutagenic – can cause damage to DNA causing changes, like benzene
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Environmental hazards
- Dangerous to the environment – pesticides, chlorofluorocarbons (CFCs)
Be aware of chemical reactions
Some chemicals may become hazardous when they react with other chemicals, through the generation of a lot of heat or producing toxic gases or compounds. An example is sodium hypochlorite (bleach) and acetic acid (vinegar), which together produce chlorine gas.
Identifying chemical hazards in your workplace
Before chemical risks can be controlled, records need to be made of the chemicals that may be present and how people might get exposed.
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Safety data sheets (SDS)
An SDS is a document that sets out a chemical's properties, hazards, safe handling and storage requirements, and emergency measures. Every manufactured chemical should have one. An SDS tells you:
- what the chemical is and its hazardous properties
- first aid measures
- fire-fighting measures
- safe handling and storage requirements
- personal protective equipment needed.
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Chemical risk assessment
A risk assessment should be carried out by a competent professional – someone with the knowledge, skills and experience to identify hazards and recommend effective controls. The assessment should cover:
- all chemical hazards present
- how chemicals are stored, handled, used and transported
- who might be exposed and how
- what controls are needed to reduce risk.
Regulatory compliance
Most countries have specific regulations covering chemical hazards. Compliance is a legal minimum, employers are responsible for meeting it as a baseline for keeping workers safe.
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What your workers need to understand
Although a competent professional should assess the risks and recommend the controls, everyone in the business should understand how to follow safe work procedures. It is good practice for employees, especially those responsible for purchasing, to have a basic understanding of the risks to workers. It is helpful to understand:
- what chemicals are used or produced?
- how much is used and how often?
- what are their hazardous properties?
- how long are people exposed for?
- what are they used for?
- how might exposure occur?
- who uses them?
- where and how are the chemicals stored?
- does anyone use them who be at greater risk? (For example, pregnant workers, young workers or those with pre-existing conditions)
Summary
- Chemical hazards exist in most workplaces – learn to recognise them.
- Safety data sheets are your most important source of information for manufactured chemicals.
- Use the hierarchy of control – start with elimination and substitution where possible.
- Engineering controls are usually more reliable than administrative controls or PPE alone.
- Consider all routes of exposure – inhalation, skin contact, ingestion and injection.
- Some workers are at higher risk and need special consideration.
- Regular review and monitoring ensure controls remain effective.
- Training and communication are essential for any chemical safety programme.
Use controls, stay safe
Working safely with chemicals isn’t about avoiding them completely - it’s about understanding the risks and putting in place proportionate, effective controls. With the right knowledge and approach, you can protect workers while allowing your organisation to benefit from the many advantages chemicals provide.
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Checklist
Follow this quick checklist to ensure chemical safety measures are in place and maintained.
- All chemicals used or produced in the workplace have been identified.
- Safety Data Sheets (SDS) are available and reviewed for each chemical.
- Risks have been assessed, and appropriate controls have been implemented or actioned.
- Workers have been trained in safe handling and emergency procedures.
- Proper labels and safe storage of chemicals is being carried out.
- Personal protective equipment (PPE) has been provided and maintained.
- There is a plan in place for spills and emergency response.
- There is a process in place to review and update chemical safety procedures regularly.
Frequently asked questions
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How do I know if the chemicals in my workplace are hazardous?
Review each substance’s Safety Data Sheet (SDS) and check its hazard classifications. If the workplace produces fumes, dusts or by‑products, these should also be assessed.
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Who should complete the chemical risk assessment?
A competent professional with the right knowledge, skills and experience should carry out the assessment and advise on appropriate controls.
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What controls should I prioritise to reduce chemical exposure?
Start with higher‑level controls such as eliminating or substituting hazardous chemicals, then consider engineering measures before relying on training, procedures or PPE.
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How often should chemical safety measures be reviewed?
Controls should be checked regularly – especially when processes change, new chemicals are introduced or exposure monitoring shows that risks may have increased.
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What should workers do if they think a chemical is being handled unsafely?
They should report concerns immediately, follow emergency procedures if needed and speak to their supervisor or OSH professional so the risk can be reassessed and corrected.
