Two ricin-laced letters were seized this week at a postal facility in Spokane - one addressed to a federal judge and another to the Spokane post office, the American Postal Workers Union said.
The letters were post marked on Tuesday, the union said.
The FBI said that the letters were seized during routine screening at a postal processing facility in Spokane, but provided no details about the case.
The APWU posted a press release Wednesday on its website after the U.S. Postal Service notified the union about the incident.
The union said that the presence of ricin was detected in preliminary tests on the letters.
Postal management told the union they had “no reason to believe that any employees are at risk from handling the suspect letters as they passed through the mail stream in Spokane,” according to the press release.
Ricin is a deadly poison derived from the castor bean plant.
The incident in Spokane comes a month after ricin-laced letters were addressed to President Obama, a U.S. senator and a Mississippi judge. Two of the letters were seized at a processing facility. The third letter reached the judge.
A Mississippi man has been arrested in that incident.
APWU President Cliff Guffey said in the union press release that the safety of postal workers is his primary concern.