ATLANTA — An incident that potentially exposed dozens of workers at the Centers for Disease Control and Prevention to anthrax is the latest in a series of safety problems at the Atlanta-based facility in recent years.

Earlier this month, lab workers at the CDC’s campus didn’t properly deactivate samples of deadly anthrax bacteria before sending them to lower-level labs to be used in experiments. Workers in the other labs also weren’t wearing adequate safety gear while handling the samples. Two or three employees who possibly came into contact with the bacteria have experienced colds or flu-like symptoms, though no one has been diagnosed with anthrax, CDC spokesman Tom Skinner said in an interview.

Seventy-three employees were on powerful antibiotics as of late Monday afternoon as a preventive measure. The agency is investigating the incident, while a team from the U.S. Department of Agriculture will conduct an independent review.

The agency has emphasized family members of CDC employees and the public are not at risk for exposure. Anthrax may be contracted through the air, but it can’t spread through human-to-human contact.

The anthrax scare is the most recent in a string of missteps that has raised concerns among legislators, federal health officials and bioterrorism experts about inadequate training, lax security and faulty equipment at the Atlanta facility.

Three separate reports by the Department of Health and Human Services’ Office of Inspector General, from 2008 to 2010, highlighted numerous problems that endangered workers and left deadly toxins vulnerable to being stolen or misplaced.

Among other problems, investigators discovered workers had not been trained properly, if at all. They also found that people not approved to handle toxins signed for package deliveries of potentially deadly substances, and inappropriately coded key cards provided workers access to secure areas they weren’t cleared to be in.

The CDC’s work is very complex, and, unfortunately, mistakes happen from time to time, Skinner said.

“We move quickly to understand why the mistake was made, and we take swift action to make sure mistakes don’t happen again,” he said. “I can’t say enough how important the safety of our workforce is. It’s top priority.”