In the EU evaluation programme for active substances, the chemical and physical properties of the active substances, such as vapour pressure, partition co-efficient, organic solvents and water solubility, are determined and assessed. The properties to be determined, the test methods and the assessment criteria are outlined in Regulation (EU) No 283/2013 and Communication 2023/C 344/02. Information on the properties of active substances is available from the "Footprint Pesticide Properties Database". A link to this database is found in the right hand column. There is also a link to the European Food Safety Authority (EFSA) which publishes reports with data and conclusions from the EU assessment of active substances. For chemical and physical properties see the document "Conclusion on Pesticides", Appendix 1.

Active substances which are used in the manufacture of plant protection products are often impure in a characteristic way. These impurities can come from starting materials or they may arise as a result of the production process or during storage. The material which comes directly from the production process is referred to as a technical active substance. When an application for authorisation is made, information on impurities must be submitted for each manufacturing site because the impurity profile is influenced by the manufacturing process and the manufacturing plant. Regulation (EU) No 283/2013 defines impurities as being significant if they are present in the technical active substance in quantities of 1 g/kg or more. Impurities of toxicological and/or ecotoxicological or environmental concern are referred to as relevant impurities. They must be declared, even at contents less than 1 g/kg. The approval of an active substance is effected by an Implementing Regulaton which states the minimum purity of the technical material as well as maximum limits for impurities. These are therefore official provisions which are to be considered for the authorisation of a plant protection product.