Oct 24, 2003 (CIDRAP News) – Environmental tests showed no signs of ricin contamination at an airport mail facility in Greenville, S.C., where an envelope containing the poison was found last week, according to the US Postal Service (USPS).
The USPS announced yesterday that the Centers for Disease Control and Prevention (CDC) took 80 environmental samples at the building Oct 22 and found them free of the poison. The CDC reported there were no indications of employee exposure or adverse health effects as a result of the incident, the USPS said.
A suspicious envelope was found at the facility Oct 15, according to the USPS. The building was closed Oct 22 after health officials determined that material in a small, sealed metal container inside the envelope was ricin, the USPS reported.
The agency said the building was scheduled to be reopened this afternoon. Mail service was not disrupted while the facility was closed.
"The Department of Homeland Security does not believe this incident is an act of terrorism," the USPS announcement said. "Both the FBI and the Postal Inspection Service are aggressively investigating. Operations at the Greenville Air Mail Facility, which were closed as a precautionary measure, are now in the process of returning to normal."
The AP report said the envelope had the typed message "caution–Ricin–poison" on the outside. The story quoted a law enforcement official as saying the envelope contained a letter warning that large amounts of ricin would be dumped into reservoirs if the federal government didn't change a requirement that truckers take a rest after 10 hours on the road.
Officials did not reveal where the letter was postmarked or to whom it was addressed, according to the AP.
Ricin is derived from waste products left after processing of castor beans. As little as 500 micrograms of ricin could be fatal to an adult if injected, but the fatal dose would be much larger if the substance were inhaled or swallowed, according to the CDC. Ricin poisoning can lead to death within 36 to 72 hours, depending on the route of exposure. There is no specific antidote for the substance.
However, the AP story quoted officials as saying it was unlikely that the author of the ricin letter could succeed in poisoning water supplies with ricin. They said it would take thousands of pounds of ricin to do it, and chemicals used in water treatment would probably render the substance harmless.
USPS Oct 23 news release
USPS Oct 22 news release
CDC fact sheet about ricin