Revista de Chimie https://revistadechimie.ro https://doi.org/10.37358/Rev.Chim.1949 Rev. Chim., 71 (12), 2020, 67-75 67 https://doi.org/10.37358/RC.20.12.8387 The Contamination Effects and Toxicological Characterization of o-Chlorobenzylidene Manolonitrile VIOREL GHEORGHE 1 , CATALINA GABRIELA GHEORGHE 1 *, ANDREEA BONDAREV 1 , CONSTANTIN NICOLAE TOADER 2 , MIHAELA BOMBOS 3 , MATEI VASILE 1 1 Petroleum - Gas University of Ploiesti, 39 Bucuresti Blvd., 100520, Ploiesti, Romania 2 Centrul de Cercetare Stiintifica pentru Aparare CBRN si Ecologie., 225 Oltenitei, 041309, Bucharest, Romania 3 National Institute for Research Development for Chemistry and Petrochemistry- ICECHIM-Bucuresti, 202 Splaiul Independetei, 060021, Bucharest, Romania Abstract: Toxicological characterization and global assessment of the toxicity of some chemicals used in the specific technique of the defense and public order system (e.g. o-chlorobenzylidene manolonitrile which enters the composition of the CS gas) is especially useful for environmental protection. Based on the results obtained, the toxicological characterization (acute lethal toxicity) and the harmful potential of some toxic substances, individual or in mixture, against euythermal sweet fish are established. The tests performed aim to change the behavior of the species studied in the presence of chlorobenzylidene manolonitrile, a substance used in the technique of defense and public order system. The tests established the toxicity values of acute lethal concentration LC50 and serve to further determine the maximum allowable concentration that inhibits the development of normal fish fauna in contaminated waters. The test results allow the toxicological characterization and measurement of the acute lethal toxicity of an inhibitor, in order to make more efficient its elimination from the contaminated environment. Keywords: o-chlorobenzylidene malononitrile, water pollutant, medium lethal concentration, LC 50 1.Introduction The widespread use of such toxic substances dates back to World War I. There are indications that such practices were used before its outbreak. At the international level, several conventions have been signed banning the use of chemicals in case of war. The most important of these conventions was signed in Paris in 1993, under the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction, which is better known as the Chemical Weapons Convention. War toxins can be classified into two main groups, lethal ones such as neurotoxics and cyanide derivatives, vesicants and suffocants and non-lethal ones, which are chemicals that cause temporary physical or mental disability and include irritants (e.g. tear gas, fumigant). Riot control agents, such as CS, are considered chemical weapons if used as a method of warfare. CS is among the most widely used and known riot control agent. CS gas is generally accepted as being non-lethal. It was first synthesized by two Americans, Ben Corson and Roger Stoughton, at Middlebury College in 1928 [1]. The defining component of the CS gas is a cyanocarbon, with chemical formula C10H5ClN2, whose structure is shown in Figure 1 and whose synthetic preparation is shown in Figure 2. Figure 1. Molecular structure of o-chlorobenzylidene manolonitrile [13] *email: ghe.catalina@yahoo.com