Toxicity measures the degree to which a substance is capable of causing damage to living organisms. Toxic substances can damage human health or the natural environment.
Under European Union (EU) legislation, hazardous chemicals are subdivided into toxicity classes according to 'Risk Phrases' assigned to individual substances, Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures (amending and repealing Directive 548/1967/EEC and Directive 45/1999/EC, and amending Regulation (EC) No 1907/2006).
The five toxicity classes, beginning with the most dangerous one, are:
- carcinogenic, mutagenic and reprotoxic chemicals;
- chronic toxic chemicals;
- very toxic chemicals;
- toxic chemicals;
- chemicals classified as harmful.