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A Guide To Hazardous Chemicals In The Workplace

A Guide To Hazardous Chemical In The Workplace

Every year thousands of workers contract illnesses via exposure to harmful chemicals in the workplace. In 2018-19 alone, 1.4m workers suffered from work-related ill-health, while 12,000 deaths occurred during the same period due to the contraction of occupational lung disease.

Such startling figures are not acceptable – and in most cases they’re avoidable. Aside from the moral implications – it’s the law (Health and Safety at Work etc. Act 1974; Control of Substances Hazardous to Health – COSHH).

In this article, we’ll provide a handy guide to hazardous chemicals, and explain how duty holders can mitigate their risk.

What are the hazardous chemicals?

Hazardous chemicals are those that pose a threat to human health. They can cause harm in numerous ways, such as by inhalation, swallowing, absorption through the skin, infection, or injury.

Hazardous chemicals come in various states: solids, liquids, gases (including vapours and fumes), and their size and form determine their toxicity. Nanoparticles can sometimes be more toxic than larger particles, for instance.

What substances are considered hazardous under COSHH?

The risk of chemical exposure applies to workers in almost every sector. Therefore, it’s the employer’s duty to protect their staff by implementing the necessary measures that eliminate potential exposure. However, the form that hazardous chemicals take can vary massively.

COSHH guidelines cover hazardous chemicals in a range of forms, including:

  • Mists
  • Dust
  • Vapours
  • Gases
  • Fumes
  • Disease-causing germs
  • Biological agents
  • Chemicals and products containing chemicals

The effects of hazardous chemicals on health

The Health and Safety Executive (HSE), asserts that chemical exposure can cause “discomfort, pain, time off work and, all too often, premature retirement and early death.” See below for specific examples.

  • Irritation, which can lead to dermatitis
  • Sensitisation, which can lead to asthma
  • Infection by bacteria
  • Loss of consciousness, from toxic fumes or inadequate oxygen
  • Chronic effects causing fatal diseases – e.g. cancer 

There are four hazardous chemical categories that differ in the way they are detected: 


Develops quickly and is easily identifiable – e.g. exposure to fumes


Difficult to link the chemical to an illness – e.g. carcinogens


Direct effect where the chemical comes into contact with the body – e.g. dermatitis on hands


Affects other or all parts of the body – e.g. chemical breathed in which causes cancer

How can employers comply with COSHH?

Employers must prevent workers’ exposure to harmful chemicals by adhering to COSHH guidelines. Where prevention is not possible, employers must adequately minimise exposure. Both prevention and minimisation are attained by carrying out a thorough risk assessment.

Below, we have listed the necessary steps employers should take to comply with COSHH, before unpacking the risk assessment process.

• Assess the risks
• Decide what precautions are needed
• Prevent or adequately control exposure
• Ensure that control measures are used and maintained
• Monitor exposure
• Carry out appropriate health surveillance
• Prepare plans and procedures to deal with accidents, incidents and emergencies
• Ensure that employers are adequately informed, trained and supervised

Hazardous chemical risk assessments

What is a risk assessment?

Risk assessments refer to the process of taking the required steps to prevent workplace ill-health. When it comes to harmful chemicals, employers must determine how, and how much, their employers are exposed to.

While tasks involving trace amounts and carry little chance of exposure, the risk is relatively low. However, common tasks such as cleaning up and chemical disposal carry high risk as the chemical can be breathed in or contact the skin.

How to conduct a risk assessment

Identify all harmful chemicals

Identify all hazardous chemicals in the workplace, before assessing the risks of each, including:

  • Those handled and stored
  • Chemicals emitted by a process
  • Chemicals produced by accident
  • Chemicals used for or caused by maintenance and cleaning

Use safety data sheets

Safety data sheets (SDS) include all the information pertaining to hazardous chemicals. Suppliers of these substances must provide relevant data sheets, which include the following:

  • Hazards, risks, and exposure symptoms
  • First aid requirements
  • Stable and reactive states
  • Handling, storage, and disposal instructions

Consider the likelihood of threat to health

After identifying all harmful chemicals, employers must consider:

  • The chemical’s hazardous properties
  • How exposure will occur (i.e. inhalation, skin contact etc.)
  • Health effects
  • Workplace exposure limits (WELs)
  • If certain groups are more at risk

Prevent exposure to harmful chemicals

When all toxic chemicals have been identified, the employer should consider the following:

  • Cease use of the chemical(s)
  • Modify the chemical process so by-products are not produced
  • Change the method so that exposure is avoided (e.g. brush the product on rather than spraying)

Chemical substitution

Harmful chemicals can also be substituted to reduce risk. Examples of chemical substitution include:

  • Using a less harmful alternative (e.g. milder cleaning products)
  • Using chemicals in a safer form (e.g. pellets instead of powder – reducing exposure to dust)
  • Not exceeding WELs

Minimise exposure to harmful chemicals

When elimination and substitution are not possible, employers must minimise risks. For control and minimisation to be adequate, employers must:

  • Ensure WELs are not exceeded
  • Comply with COSHH guidelines
  • Design and provide efficient work processes and procedures
  • Minimise chemical exposure at the source
  • Provide adequate PPE

Employee skills and experience

Employee skills and experience

While risk assessments are essential, they are not fool proof; therefore, all workers who work with or around harmful chemicals must be qualified to do so. To ensure a risk assessment is comprehensive, employers should include their employees in the process, encouraging them to suggest improvements and report problems.

Employers must also provide training where necessary and monitor future exposure to harmful chemicals according to WELs. Finally, employers should conduct staff health checks at appropriate intervals.

How to dispose of chemical cleaning products

Once work with chemicals is completed, all chemicals must be disposed of safely and efficiently, as per the Environment Protection Act 1990. As we’ve covered, harmful substances can be identified by their CLP classification, Safety Data Sheets (SDS), and government guidelines to hazardous waste.

Businesses should use an authorised waste contractor to handle and dispose of their waste, including hazardous waste. For more information, we always recommend contacting your local council to find out how to dispose of waste from your business if you are not sure.

We stock a wide range of environmentally-friendly cleaning products and biological cleaning products from brand like InnuScience, giving you the option to reduce the potential damage to the environment you cause through chemical waste.

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