WEDNESDAY, April 17 (HealthDay News) -- A preliminary, inconclusive test suggests the deadly toxin ricin was in a letter sent to President Obama on Tuesday, officials report.
The case is being investigated by the U.S. Secret Service.
The letter was intercepted at the White House mail screening facility, which is not located near the White House complex, USA Today reported Wednesday.
The preliminary test showed evidence of ricin, but the FBI said only a complete second test can confirm if the letter actually did contain the deadly poison, the Associated Press reported.
Ricin, which is found in the castor oil plant, can prove deadly if inhaled, one expert noted.
"Without a doubt, ricin is toxic," said Victoria Richards, a toxicologist and assistant professor of medical sciences at the Frank H. Netter MD School of Medicine at Quinnipiac University in Connecticut.
"If castor beans are eaten [about 20 for an adult] death can occur in six to eight days," Richards said. "When concentrated, ricin powder may be lethal in a much shorter timeframe. There is a process called oral inhalation, in which powders or aerosolized agents [depending on the particle size] can be deposited in the mouth and eventually swallowed."
If swallowed, "ricin will cause nausea, vomiting, bloody diarrhea and dehydration," Richards added. "Multiple organ damage also occurs, and eventually death."
At least three U.S. senators also reported receiving suspicious mail in recent days. A letter sent to Sen. Roger Wicker, R-Miss., tested positive for ricin in a preliminary test. On Wednesday morning, a suspicious letter was received by Sen. Richard Shelby, R-Ala., and a suspicious package was received by Sen. Carl Levin, D-Mich.
"We do not know yet if the mail presented a threat," Levin said, USA Today reported.
The letter received by Wicker on Tuesday contained a "white granular substance" and was quarantined before the initial test indicated that the substance was ricin. The letter was intercepted at an off-site mail facility. The material has been sent to an accredited laboratory for further analysis.
The president was briefed on the suspicious letters on Tuesday night and again on Wednesday morning, said White House Press Secretary Jay Carney, USA Today reported.
For more on ricin, head to the U.S. Centers for Disease Control and Prevention.