Less Than A Raindrop: How Much Is A 'Fatal Dose' Of Novichok?

What are the chances of survival for Russian opposition leader Aleksei Navalny? German authorities say he was poisoned with Novichok, a military-grade nerve agent intended to kill him. Ismail Efendiyev from the European Association of Poison Centers and Clinical Toxicologists (EAPCCT) says a dose 30 times smaller than a raindrop can be fatal -- but that Navalny's German doctors are likely gaining crucial insight into his treatment from British colleagues with experience from the 2018 Salisbury Novichok poisoning.