The Pentagon this week said that it accidentally sent live anthrax samples to government and private laboratories in at least nine states, and to a US military base in South Korea. As the Associated Press reports, the samples originated from a Department of Defense lab in Utah, which was supposed to send out killed samples. The labs were not equipped to handle the live spores they received instead, though military officials say there is no indication that the potentially fatal bacteria poses a broader health risk, and exposed workers are undergoing treatment.

"an abundance of caution"

"There is no known risk to the general public, and there are no suspected or confirmed cases of anthrax infection in potentially exposed lab workers," Pentagon spokesman Col. Steve Warren told reporters Wednesday. He added that the Department of Defense has suspended all shipments of the material until an investigation is completed, citing "an abundance of caution."

ABC News reports that the samples were shipped on April 30th to labs in California, Delaware, Maryland, New York, New Jersey, Tennessee, Texas, Virginia, and Wisconsin. According to NBC News, they were shipped via FedEx. Only the Maryland samples have been confirmed as live Bacillus anthracis, the bacteria that causes anthrax, though it is suspected that the others received live spores from the same batch. Four workers at commercial labs in the US are undergoing post-exposure treatment, the BBC reports, as are 22 military personnel at the Osan Air Base in South Korea.

The Centers for Disease Control and Prevention (CDC) has launched an investigation that will involve on-site testing as well as lab tests of the remaining samples. The CDC was involved in its own anthrax-related mishap last year, after 75 workers were accidentally exposed to live samples. The agency also mistakenly sent contaminated bird flu samples to a lab last March, though neither incident caused infection among exposed workers.

The Dugway Proving Ground, which shipped the samples, is an isolated facility in Utah focused on biological and chemical weapon defense. It was temporarily closed in 2011 after a vial of VX nerve agent was misplaced.