The Pentagon says an investigation into an accidental shipment of live anthrax to labs in nine states and South Korea was significantly larger and lasted over a decade.

The anthrax, sent from the Dugway Proving Ground in Utah, has been shipped to 51 sites in the United States and overseas in the last 10 year.  The samples were all believed to have contained irradiated and inactivated virus.

The officials admitted they are testing 400 additional batches and if they are found to be live, the number of locations with live virus could significantly jump.

Deputy Defense Secretary Robert Work said that 31 lab workers have ben undergoing post-exposure treatment as a precaution but that the public is safe.

“We know of no risk to the general public from these samples,” Work said.

The admission of the shipments of live anthrax are part of a pattern of accidents involving viruses that have observers questioning the way the military is handling potentially deadly pathogens.  A year ago, the CDC admitted a dozen employees may have been exposed to live anthrax and that another lab contaminated a flu virus with the deadly H5N1 bird flu and then shipped it out to another laboratory.

Less than a year ago, live smallpox vials were found in a storage lab at the National Institutes of Health.