A letter addressed to President Barack Obama tested positive for the poison ricin, said NBC News.
The letter to Obama was intercepted at an off-site White House mail facility and was being tested further, said NBC News. A federal law enforcement official said that the letter was “very similar” to one addressed to Sen. Roger Wicker, R-Miss.
Ricin is made from castor beans and can kill within 36 hours. There is no antidote. Some threatening letters simply contain ground castor beans, resulting in a positive field test for ricin without the concentrated poison. Results from full laboratory tests are expected in the next 24 to 48 hours, NBC News said.
People can be exposed to ricin by touching a ricin-laced letter or by inhaling particles that enter the air when the envelope is opened. Touching ricin can cause a rash but is not usually fatal. Inhaling it can cause trouble breathing, fever and other symptoms, and can be fatal.