The three suspicious envelopes sent to the White House and Pentagon on Monday contained castor seeds and not ricin in its extracted form which can kill if inhaled.
Pentagon spokeswoman Dana White made the clarification on Wednesday and said the FBI was still investigating.
Ricin can be extracted from the seeds which can be lethal if eaten in large quantities but otherwise harmless.
If a person is exposed to ricin in its extracted form, they can die within 72 hours by inhaling much smaller amounts of the toxin which causes respiratory failure.
US Defense Department personnel work in the mail room at the Pentagon where two of the envelopes were found yesterday. The envelopes contained castor seeds and not actual ricin but they triggered alarms in the screening process
The workers screened all the other mail as a precaution after the initial scare. The letters were sent by a former Navy sailor who, it is claimed, left a return address on the mail
All mail that was sent to the Pentagon’s mailing room on Monday and received on Tuesday was placed in quarantine after the scare
None of the envelopes reached their intended targets.
The envelopes contained castor seeds which (file image shown) which ricin can be extracted from. They can cause deadly illness if eaten in large quantities but do not pose any form of risk to air
They set off alarms in off-site mailing facilities which detect ricin or other poisonous elements in incoming packages.
Fox News cites unnamed officials who say the letters were sent by one man – a former Navy sailor who they were led to because he left a return address on them.
He has not been named and no charges have yet been filed.
The first two envelopes that were addressed to Secretary of Defense James Mattis and Chief of Naval Operations John Richardson.
They triggered alarms during screening at a mail facility which is not inside the main building but is nearby, defense officials said. They were sent to the FBI for additional testing.
A third envelope was reported by the Secret Service as being intercepted before arriving at the White House
Officials say the first two were addressed to Secretary of Defense James Mattis (pictured left) and Chief of Naval Operations, John Richardson (right)
At around the same time, two people were hospitalized after being exposed to a white powder that was contained in mail sent to Sen. Ted Cruz’s Houston campaign office.
Their injuries are not known. Neither of the victims worked for Cruz’s campaign.
It is not known if the two incidents are linked or what the substance sent to Cruz’s office was.
After the incident at Cruz’s office, the Houston Fire Department conducted tests in the building but no harmful substances were found.
The envelopes were intercepted in the mailing facility which is not inside the Pentagon (pictured on Tuesday)
All mail that was sent to the Pentagon was placed under quarantine as a precaution.
Ricin exposure can lead to death if the toxin is inhaled directly. It is commonly used in terror plots.
It remains unclear what form it was sent to the Pentagon in. In a statement, the FBI confirmed its investigation.
‘On Tuesday, October, 2, 2018, in coordination with the Pentagon Force Protection Agency, FBI Special Agents took possession of two suspicious envelopes that had been screened at the Pentagon mail facility.
‘Those envelopes are currently undergoing further testing.
At around the same time as the announcement from the Pentagon was made, two people were hospitalized after being exposed to a white powder at Sen. Ted Cruz’s Houston campaign office (pictured)
‘As this is ongoing, we will have no further comment,’ a spokesman said.
Ricin causes a painful deaths which begin with nausea and vomiting.
The toxic components then cause internal bleeding and ultimately lead to respiratory failure.
Several terror plots which use the toxin have been foiled in Europe in the past including an intended attack on a London Underground station in 2003 and a separate attack in Germany in June this year.
After initial exposure to ricin, symptoms ordinarily appear in around 10 hours and death can occur within 72 hours.
Since the anthrax attacks which killed five people after the powder was distributed through mail in 2003, the US Government has increased measures to protect workers and officials from exposure to any harmful substances.
They include putting mail through X-Ray machines and scanners which detect vapors and identify anything poisonous or toxic.
In Washington DC, the US Postal Service also samples the air as mail is being sorted before it is sent to government buildings.