US Defense Department personnel, wearing protective suits, screen mail as it arrives at a facility near the Pentagon in Washington, DC on October 2, 2018. - Two or more packages delivered to the Pentagon this week were suspected to contain the deadly poison ricin, an official said. Produced by processing castor beans, ricin is lethal in minute doses if swallowed, inhaled or injected and 6,000 times more potent than cyanide, with no known antidote. US Defense Department personnel wear the protective suits as a matter of routine. (Photo by Thomas WATKINS / AFP) (Photo credit should read THOMAS WATKINS/AFP via Getty Images)