The OECD Guidelines for the Testing of Chemicals are a collection of about 100 of the most relevant internationally agreed testing methods used by government, industry and independent laboratories to identify and characterise potential hazards of new and existing chemical substances, chemical preparations and chemical mixtures. They are a basic set of tools used primarily in regulatory safety testing and subsequent chemical and chemical product notification and chemical registration. In addition, they can also be used for the selection and ranking of candidate chemicals during the development of new chemicals and products and in toxicology research. They cover tests for physical-chemical properties of chemicals, human health effects, environmental effects, as well as degradation and accumulation in the environment. Adopted in 1981, the Guidelines have become the recognised reference tool for professionals working on the testing of chemicals and the assessment of their potential hazards.