(CNN) -- The head of the bioterrorism lab involved in potentially exposing dozens of workers at the Centers for Disease Control and Prevention to deadly anthrax bacteria has resigned.
Michael Farrell, who headed the Bioterrorism Rapid Response and Advanced Technology (BRRAT) Laboratory, submitted his resignation Tuesday, CDC spokesman Tom Skinner told CNN. He had been reassigned from his post last month, after the anthrax incident was made public.
The CDC says the potential anthrax exposure happened between June 6 and June 13. The BRRAT lab had been preparing anthrax samples for use in two other labs on the CDC's Atlanta campus and failed to adequately deactivate the samples.
According to a CDC investigation report, the exposure happened because the lab didn't use an approved sterilization technique. It didn't have a written plan reviewed by senior staff to make sure all safety protocols were followed, and there was a limited knowledge of peer-reviewed literature about the process that would make it less dangerous. The lab also did not have a standard operating procedure that would make sure the transfer of the material would be safe.
Bottom line, "the scientists failed to follow a scientifically derived and reviewed protocol that would have assured the anthrax was deactivated," CDC Director Tom Frieden said. It "should have happened, and it didn't."