In 2018, certain types of nitrosamines (N‑nitrosodiethylamine (NDEA) and N-nitrosodiethylamine (NDMA)) were detected in a number of active substances used in the treatment of hypertension and in related medicines. Nitrosamines are known as possible carcinogens for humans: only very low amounts are acceptable according to current regulatory requirements (ICH M7 “cohort of concern”). Their detection requires highly sensitive analytical methods. As clarified by the European Medicines Agency (EMA), their presence in active substances may be linked to several factors, e.g. from processing conditions to accidental introduction due to cross-contamination (from processes running in parallel on the same production lines) or recovery procedures for solvents, or also from degradation of the substances.