VX is a topical agent. LD-50 on VX is 5mg for a 70kg human. That's 30 grains of salt. VX was discovered at Porton Down in the early '50s, continuing research done by IG Farben in the '30s. Kim Jong-un used it to poison his brother in law in 2017. VX is so old-school that the technique for administering an agonist is what gave us the epipen. That which my daughter has to carry around in case of peanuts was developed in case the USSR decided to fumigate Western Europe as the tanks rolled. Kolokol-1, the agent used in the "rescue" of the Moscow Opera House in 2002, is believed to be an aerosolized carfentanil derivative. LD-50 on fentanil is 2mg (12 grains of salt) with an LD-50 on carfentanil estimated at approximately 1% that of fentanil (one tenth of a grain of salt). They want everyone to know they tried to kill Navalny.