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Hazardous Substances (COSHH)

Health and SafetyIn this section:

The Control of Substances Hazardous to Health Regulations 2002 (as amended 2004) (COSHH) [1,2] require employers to undertake an assessment of and control any substance that might present a hazard to employees and others (e.g. patients; visitors; staff repairing or servicing reusable dental equipment; dental laboratory staff handling dental impressions and appliances).

Hazardous substances can take the form of solids, liquids, gases, fumes, dust or biological agents. Exposure to these substances can be by swallowing, inhaling, skin puncture or absorption through the skin or eyes.

COSHH covers:

  • Substances or preparations that are classified as ‘dangerous’ under the Chemicals (Hazard Information and Packing Supply) Regulations 2009 (CHIP 4) [3] and European Regulation on Classification, Labelling and Packaging of Substances and Mixtures (CLP) [4].
    NB: under the European REACH Regulations [5] which operate alongside COSHH, suppliers of such substances must provide a Material Safety Data Sheet (MSDS) for users. The MSDS is used to assist with the completion of a COSHH Risk Assessment.

* Note: Following Brexit, European Union REACH Regulations no longer apply to the UK. UK REACH Regulations replace these.


  • Substances with a workplace exposure limit (WEL). WELs have replaced maximum exposure limits (MELs) and occupational exposure standards (OESs). WELs only apply to substances that can be inhaled, e.g. nitrous oxide, mercury, detergent powder.
  • Biological agents that are classified into four hazard groups depending on: their ability to cause infection; the severity of the disease that might result from exposure; the risk that the infection might spread to the community; and the availability of vaccines for effective treatment.
  • Dust in substantial quantities.

COSHH does not cover lead, asbestos or radioactive substances; these substances have their own regulations.

Hazardous substances in the dental practice that need assessment and control include:

  • Potentially infected blood and body fluids;
  • Chemicals (e.g. cleaning fluids), assessment of which will generally be straightforward, covering points such as storage in a safe place and what to do in case of spillage;
  • Mercury, including amalgam, which requires adequate facilities and staff training to ensure safe handling (see Mercury Handling);
  • Latex (see Latex Allergy);
  • Products for cosmetic procedures, e.g. Botox®.

The Health and Safety Executive [6,7] and Healthy Working Lives [8] provide further, more detailed information about COSHH.

Sources of Information

  1. Control of Substances Hazardous to Health Regulations 2002 (www.legislation.gov.uk/uksi/2002/2677/contents/made)
  2. Control of Substances Hazardous to Health (Amendment) Regulations 2004 (www.legislation.gov.uk/uksi/2004/3386/contents/made)
  3. Chemicals (Hazard Information and Packaging for Supply) Regulations 2009 (CHIP 4) (www.legislation.gov.uk/uksi/2009/716/contents/made)
  4. European Regulation on Classification, Labelling and Packaging of Substances and Mixtures (CLP)  (https://osha.europa.eu/en/themes/dangerous-substances/clp-classification-labelling-and-packaging-of-substances-and-mixtures)
  5. REACH [webpage]. Health and Safety Executive (www.hse.gov.uk/reach)
  6. Working with Substances Hazardous to Health: A brief guide to COSHH. Health and Safety Executive (2012) (www.hse.gov.uk/pubns/indg136. (PDF))
  7. COSHH [webpage]. Health and Safety Executive. (www.hse.gov.uk/coshh)
  8. Hazardous Substances [webpage]. Healthy Working Lives, Public Health Scotland (www.healthyworkinglives.scot/workplace-guidance/safety/hazardous-substances)