Hazardous substances

Substances hazardous to health are defined in UK legislation under the Control of Substances Hazardous to Health Regulations 2002 (COSHH) as those that are 'Very Toxic, Toxic, Corrosive, Harmful or Irritant.' COSHH applies to a very wide range of substances and preparations (mixtures) with the potential to cause harm if they are inhaled, ingested or come into contact with, or are absorbed through, the skin.

To comply with COSHH you need to:

• assess the risks to health;
• 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 foreseeable accidents, incidents and emergencies; and
• ensure that employees are properly informed, trained and supervised.

Suppliers of chemicals must provide an up-to-date safety data sheet for all substances classed as ‘dangerous for supply’. They provide information on substance hazards, safe handling, storage and emergency measures. This information is helpful to users of chemicals in making their own risk assessments under COSHH.

COSHH implements the requirements of the Chemical Agents Directive (EU no.98/24/EC) and places a strong emphasis on prevention of exposure to hazardous substances in order to prevent workers suffering ill health. Where prevention is not possible then exposure must be adequately controlled by applying the principles of good control practice.