Valenzuela-Tapia_2025_Toxics_13_

The historical use of toxic chemicals to cause intentional harm has evolved from blister agents in World War I to highly lethal organophosphates and emerging families of chemicals, such as Novichok. In turn, medical or recreational substances like fentanyl, lysergamides, and phencyclidine pose a growing risk of hostile use, particularly related to the rapid proliferation of new psychoactive substances (NPSs). A narrative literature review was conducted covering specialized databases (PubMed, ScienceDirect, SciELO, Google Scholar) and sources from international organizations (OPCW, UNODC, ONU), analyzing historical and recent cases of the use of nerve agents in conflicts and the use of NPSs for hostile purposes. The main families of conventional agents (G, V, A series, and Novichok) and NPSs (lysergamides, PCP, fentanyl derivatives) were identified, highlighting their ease of synthesis, high toxicity profiles, and the regulatory gaps that facilitate their illicit production. In this scenario, it is essential to strengthen regulatory frameworks, surveillance systems, and ethical protocols in chemical research, as well as to promote international cooperation to prevent these substances from becoming chemical threats.