(Reuters) - The director of a U.S. government bioterror lab that potentially exposed scores of workers to live anthrax last month has resigned, the U.S. Centers for Disease Control and Prevention said on Wednesday.

Michael Farrell, head of the CDC's Bioterror Rapid Response and Advanced Technology Laboratory (BRRAT) in Atlanta, had been reassigned from his position last month after the agency disclosed the safety breaches. He submitted his resignation on Tuesday, the CDC said.

“I can confirm that he was the team lead for the BRRAT lab since 2009 and that he’s resigned from that position,” said CDC spokesman Thomas Skinner. He could not provide further details on Farrell's departure, or whether additional personnel changes at the public health agency were imminent.

Farrell could not be reached for comment.

He was the first CDC employee to leave his post over the incident, in which more than 80 government lab workers were potentially exposed to the dangerous bacteria after samples that had not been properly inactivated left the BRRAT lab in June.

No one has fallen ill as a result of the incident, and the CDC has concluded that there was minimal, if any, actual risk of exposure.

But the lapse prompted new scrutiny into how the agency protects the public from potentially dangerous research. The CDC's director, Dr. Thomas Frieden, has also pledged to change the culture of safety among its staff.

Frieden has said the agency would consider disciplinary action against any staff members found to have knowingly violated safety protocols or to have failed to report breaches.

Frieden has appointed a CDC scientist to a new role overseeing laboratory safety and said he expects to announce a new advisory panel of independent experts this week.

Some biosafety experts have urged the CDC to focus on better training its staff to identify and respond to lapses more quickly rather than cast blame for problems that have repeatedly cropped up in its labs over the last decade.

“For (Farrell) to resign as a result of this is an indicator that they’re focusing on who instead of what. It was a culture that led to this issue. It was not an individual,” said Sean Kaufman, a former CDC official and biosecurity expert who is president and founding partner of consultancy Behavioral-Based Improvement Solutions. He testified about the lapses last week before lawmakers in the U.S. House of Representatives.

The bioterror lab was set up in 1999 as a central point of entry for testing samples suspected of containing biological agents.

It develops rapid testing methods and provides oversight to a corresponding national Laboratory Response Network, which links state and local public health laboratories designed to identify potential bioterror threats. Part of their mission is helping local authorities detect biological and chemical agents.

In the anthrax incident, BRRAT lab scientists were preparing samples of inactivated bacteria for colleagues in a lower-security lab who were developing a new test for detecting anthrax in suspicious powders.

After sending the samples to the lower-security lab, where workers wear less protective gear, BRRAT staff found live anthrax on a plate left over from the preparation process, raising concerns the samples were not fully inactivated. Later checks of the lower-security lab did not show the presence of live anthrax.