American researcher Matt Boisen works in the Lassa fever laboratory at Kenema Government Hospital in southeastern Sierra Leone, February 7, 2011. Boisen's laboratory in southeastern Sierra Leone is an outpost of the U.S. government's "war on terror", funded by a surge in bio-defence spending since the airplane and anthrax attacks on New York and Washington a decade ago. American research aims to limit the vulnerability of western interests to biological agents. In the case of Lassa swift and simple diagnosis is seen as critical to doing that. Picture taken February 7, 2011. Reuters/Simon Akam

Up to 75 scientists working in a U.S. government laboratory in Atlanta may have been exposed to live anthrax bacteria, the Centers for Disease Control and Prevention (CDC) said on Thursday.

The CDC says it immediately began treating individuals potentially exposed to the deadly bacteria, and a spokesman said the risk of infection was "very low."

According to Reuters, the exposure happened on June 13 after researchers working at a high-level lab failed to deactivate the anthrax before transferring samples to a lab without the capability to handle live anthrax. Up to seven scientists may have had direct contact with the anthrax, but the CDC offered 75 employees a 60-day antibiotic treatement and an anthrax vaccine.

Dr. Paul Meechan, director of the environmental health and safety complicance office at the CDC, said the agency is investigating the exposure to determine how it happened and whether it was intentional.

Anthrax typically incubates for five to seven days before affecting the infected individual. Anthrax bacteria release spores that go dormant until reaching a host. The spores can survive in the open environment for extended periods of time, even "decades," according to the CDC.

Anthrax gained worldwide attention in October 2001, when an envelope filled with anthrax powder was sent to Senate Majority Leader Tom Daschle at the Hart Senate Office Building.