About 75 scientists may have been exposed to live anthrax bacteria in government laboratories in Atlanta and are being treated to prevent the infection, the Centers for Disease Control and Prevention said.

The CDC scientists were working in lower-security labs not equipped to handle live anthrax and received samples of the bacteria from a higher-security lab, the agency said. The unintentional exposure was discovered June 13 when live bacteria were found on the original bacteria plates during disposal, CDC spokesman Tom Skinner said. "Based on most of the potential exposure scenarios, the risk of infection is very low," Skinner said.

Anthrax is a deadly infection caused by the spore-forming bacillus anthracis, more often found in cows and sheep than humans. The CDC is giving potentially exposed workers protective antibiotics and doesn't believe other CDC staff, family members or the general public are at risk, Skinner said.

Anthrax was highlighted as a potential weapon of mass destruction in 2001 when mail laced with the spores was sent to media organizations and the offices of some U.S. senators. Five people died.

A CDC investigation found lab staff sent samples that were supposed to be inactive to the lower-security labs. The proper procedures weren't followed and live bacteria were transferred to workers who didn't wear protective gear, the agency said.

"It shouldn't happen, but it is hard to keep accidents from happening," said John Keene, president of Global Biohazard Technologies Inc. Still, Keene said accidental exposures like this are "very, very rare."

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