For the first time, compounds that protect against ricin poisoning have been identified by French researchers. It's hoped the research could lead to an antidote for the poison, which is a thousand times more toxic than cyanide. Banned under chemical weapons conventions, ricin became infamous when a modified umbrella-gun containing a poisoned pellet was used to kill Bulgarian dissident Georgi Markov in 1978. Although not as potent as synthetic nerve agents, ricin is obtained from a natural source - the castor bean - so could potentially be more easily obtained by terrorist groups. Research has been undertaken into an antibody-based vaccine and...