The Pentagon says the case of live anthrax spores accidentally shipped to commercial and military labs in the U.S. and overseas is much worse than first reported.

An initial review says 51 labs in 17 states and Washington, D.C., and in three other countries – Australia, Canada, and South Korea – may have gotten the potentially dangerous shipment.

Deputy Defense Secretary Robert Work on Wednesday said those numbers could grow as the investigation proceeds. But Work stressed there is no danger to the general public and little risk for the lab workers.

“There are no suspected or confirmed cases of anthrax infection among any workers in any of the labs that have received these samples over the last 10 years,” said Work.

He also said the concentration of the samples were too low to infect the average healthy person.

The U.S. Centers for Disease Control is leading the investigation.

The anthrax samples were sent out from a U.S. military laboratory in the western state of Utah. Work says the probe will focus on why radiation failed to kill the spores and why testing failed to reveal that the spores were not dead.

The anthrax was being used to develop a test to identify biological threats in the field.

Contact with live anthrax can lead to a severe flu-like illness that could be fatal if not treated early.

  anthrax, labs, pentagon