According to a classified report by the
United States ArmyNational Ground Intelligence Center,[9] the agent designated as
A-232 and its ethyl analog A-234, developed under the FOLIANT program, were "as toxic as
VX, as resistant to treatment as
soman, and more difficult to detect and easier to manufacture than VX".
No certain data on toxicity exist but it is estimated that the median lethal concentration of A-234 is 7 mg/m3. This means that half of 70 kg men under slight physical activity – breathing 15 litres of air per minute – would die within two minutes of exposure. This equates to median lethal dose of 0.2 mg via respiration.[10]
Regulated chemical under the Chemical Weapons Convention
A-234 has recently (entry into force 7 June 2020) been added to
Schedule 1 of the Annex on Chemicals of the
Chemical Weapons Convention and it has been explicitly named as an example compound for schedule 1.A.14.[11][12] For chemicals listed in Schedule 1, the most stringent declaration and verification measures are in place combined with far-reaching limits and bans on production and use. It is notable to say that Annex 1 does not explicitly relate this structure to the name A-234, instead adding this particular structure to the prohibited compounds section.
An alternative structure for A-234 and the related Novichok agents had previously been proposed by Western chemical weapons experts such as Steven Hoenig and D. Hank Ellison.[13][14][15] These structures were supported by Soviet literature of the time and were tested as
acetylcholinesterase inhibitors,[16][17][18] however Mirzayanov explained that a number of weaker agents developed as part of the Foliant program were published in the open literature as organophosphate
pesticides, in order to disguise the secret nerve agent program as legitimate pesticide research.
However, the presence of a carbonimidic chloride fluoride group and a dimethylchloroethyl group suggest that this molecule is a member of the C-series of organophosphate agents (C01), with additional mustard and (chlorofluoro-)phosgene oxime radicals, added to produce skin and lung toxicity as well as
blistering effects.[19]
^Hoenig, Steven L. (2007), Compendium of Chemical Warfare Agents, Springer,
ISBN978-0-387-34626-7
^Ellison, D. Hank (2008), Handbook of Chemical and Biological Warfare Agents (Second ed.), CRC Press,
ISBN978-0-849-31434-6
^Jeong K, Choi J. Theoretical study on the toxicity of 'Novichok' agent candidates. R Soc Open Sci. 2019 Aug 7;6(8):190414.
doi:
10.1098/rsos.190414PMID31598242
^Kruglyak, Yu. L.; Malekin, S. I.; Martynov, I. V. (1972). "Phosphorylated oximes. XII. Reactions of 2-halophospholanes with dichlorofluoronitrosomethane". Zhurnal Obshchei Khimii. 42 (4): 811–814.
^Raevskii, O. A.; Chapysheva, N. V.; Ivanov, A. N.; Sokolov, V. B.; Martynov, I. V. (1987). "Effect of Alkyl Substituents in Phosphorylated Oximes". Zhurnal Obshchei Khimii. 57 (12): 2720–2723.
^Raevskii, O. A.; Grigor'ev, V. Yu.; Solov'ev, V. P.; Ivanov, A. N.; Sokolov, V. B.; Martynov, I. V. (1987). "Electron-Donor Functions of Ethyl Methylchloroformimino Methylphosphonate". Zhurnal Obshchei Khimii. 57 (9): 2073–2078.