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Chemical safety essentials: what everyone should know

An essential guide to recognising and managing chemical risks at work

Chemicals can be found in almost every type of workplace, which makes knowing how to spot them and handle them safely vital for protecting people and meeting legal duties where required.

In this resource

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). They can be:

  • Naturally occurring - minerals like asbestos or gases like methane
  • Manufactured - such as cleaning products or industrial chemicals
  • By-products - created during industrial processes, like welding fumes.

While many chemicals are useful and necessary, they may also be harmful and/or hazardous, and 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:

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.

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 etc.
  • Carcinogenic – cancer-causing substances like silica dust, diesel fumes, asbestos
  • Mutagenic – can cause damage to DNA causing changes, like benzene
  • Toxic reproduction – can affect fertility or harm unborn children, such as lead and phthalates.

Environmental hazards

  • Dangerous to the environment – pesticides, chlorofluorocarbons (CFCs)

Some chemicals may become hazardous when they react with other chemicals, through the generation of a lot of heat or producing toxic gases and/or compounds. Examples include sodium hypochlorite (bleach) and acetic acid (vinegar), which together produce chlorine gas.

How chemicals enter the body

Understanding the routes of exposure helps you select effective controls:

Inhalation (breathing in)

  • Most common route for workplace exposure
  • Includes vapours, gases, dust, mist and fumes
  • Goes directly to the lungs into the bloodstream

Absorption (skin/eye)

  • Many chemicals can pass through the skin
  • Eyes are particularly vulnerable to chemical splashes
  • Can happen without you noticing

Ingestion (swallowing)

  • Usually accidental - contaminated hands, food or drink
  • Can occur through poor hygiene practices
  • Less common but can be profoundly serious

Injection

  • Through cuts, puncture wounds or needlestick injuries
  • Direct route into bloodstream
  • Medical and laboratory workers at particular risk

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. 

A safety data sheet (SDS) is a document that provides detailed information about a chemical’s properties, including hazards, safe handling, storage, and emergency measures. They are your most valuable resources for understanding manufactured chemicals. They tell you:

  • what the chemical is and its hazardous properties
  • first aid measures
  • fire-fighting measures
  • safe handling and storage requirements
  • personal protective equipment needed.

A chemical risk assessment should be completed by a competent professional. They should record all chemical hazards and make recommendations for their storage, handling, use and transport - these may be described as 'risk controls'.

A business’ control of hazardous substances such as chemicals may be subject to inspection by authorities, as most countries have specific regulations covering chemical hazards. It is an employer’s responsibility to comply with these as a minimum approach to keeping workers safe.

Note: a 'competent professional' is someone who holds a combination of knowledge, skills, experience and attributes, which is a quality or feature regarded as a characteristic or inherent part of someone, and can also be described as attitudes or behaviours.

Key questions about keeping workers safe from chemicals

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?
  • what are their hazardous properties?
  • what are they used for?
  • who uses them?
  • does anyone use them who might be at greater risk, such as pregnant workers, young workers, or workers with existing health conditions?
  • how much is used and how often?
  • how long are people exposed for?
  • how might exposure occur?
  • where and how are the chemicals stored?

Understanding this information about your working environment will help you keep people safe and support compliance.

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.

Key takeaways

  • 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

Remember: 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 whilst allowing your organisation to benefit from the many advantages chemicals provide.

This guide aligns with IOSH's competency framework at the 'understand' level for risk identification and profiling, risk assessment and analysis, risk prioritisation, and risk control, mitigation and resilience.

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Frequently asked questions

    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.

    A competent professional with the right knowledge, skills and experience should carry out the assessment and advise on appropriate controls.

    Start with higher‑level controls such as eliminating or substituting hazardous chemicals, then consider engineering measures before relying on training, procedures or PPE.

    Controls should be checked regularly – especially when processes change, new chemicals are introduced or exposure monitoring shows that risks may have increased.

    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.