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Hazardous Substances

What is a hazardous substance?

A substance hazardous to health is anything that is hazardous in the form in which it may occur in the work activity. It need not just be chemical compounds, it can include chemical mixtures, micro-organisms, natural materials such as flour, or processed materials such as wood dust, etc.

When using substances which are potentially hazardous to health, your risk assessment will require all of the substances involved in the process to be assessed, and for the appropriate controls to mitigate the risks to be implemented. In some situations a formal detailed 'Control of Substances Hazardous to Health' or 'COSHH' assessment may be required in addition to the process or activity risk assessment. Where you have an activity that is:-

  • Readily repeatable;
  • Has step by step instructions available (eg in a standard operating procedure or SOP);
  • The controls in place are suitable and operating (eg a fume cupboard);
  • Users are trained, competent and supervised for the activity;
  • Additional specific first aid measures are not required (eg medical oxygen treatment)

a 'Substance Information Note' (SIN) or 'Technical Information Note' (TIN) may be suitable, providing it provides you with sufficient information to manage the risks involved. Check that there is nothing about your activity, the people conducting the work, the environment you are working in, or the equipment you are using that could make it invalid. Where the activity and the SIN/TIN is deemed suitable, then this should simply be referenced as one of your control measures within your activity based risk assessment where the relevant hazardous substances are involved or are generated by the process.

Please use the links in the right hand column for further information.

Essential information about hazardous substances is available on the Safety Data Sheet (sometimes also referred to as an SDS, Safety Data Sheet): see guidance on how to interpret this information.

Regurgitating a Safety Data Sheet does NOT constitute a COSHH assessment

University Links

For Policy on Substances Hazardous to Health see COSHH Assessment

Control of Substances Hazardous to Health (COSHH) Assessment

Substance Information Notes (SIN'S)

Technical Information Notes (TIN'S)

External Links

COSHH Basics - what is a substance hazardous to health? by the HSE

EH40 - Containing the list of Workplace Exposure Limits (WELs) for use with the Control of Substances Hazardous to Health Regulations 2002 (as amended)