Since N-nitrosamines, possible carcinogens for humans, were detected in 2018 in a number of active substances, the EDQM has been working with regulatory authorities to ensure that no medicinal products containing nitrosamine contaminants reach the end user. This has involved, among others, reviewing Certificates of suitability (used in marketing authorisation applications), revising European Pharmacopoeia monographs for the active substances concerned and establishing new reference standards to support the implementation of the new Ph. Eur. general chapter on the analysis of N-nitrosamines. The EDQM OMCL Network has also co-ordinated the development of testing procedures that ensure adequate control of impurities and a risk-based sampling and testing programme.