Anthrax . Smallpox . A potentially deadly strain of the flu virus . The American public trusts the Centers for Disease Control and Prevention to handle dangerous biological materials , but recent incidents have put a damper on the agency 's reputation , members of Congress said Wednesday . `` What happened was completely unacceptable , '' CDC Director Dr. Tom Frieden said in his testimony before the Energy and Commerce Committee 's subcommittee for Oversight and Investigations . `` It never should have happened . '' Rep. Tim Murphy , R-Pennsylvania , the subcommittee chairman , opened the hearing by summarizing the troubling incidents that have come to light over the past month . In early June , dozens of CDC workers were potentially exposed to anthrax after a lab failed to inactivate the dangerous bacteria before transferring it to a lower lab . A subsequent investigation revealed `` an alarming series of failures , '' according to one of the subcommittee members , including an incident of cross contamination between a relatively safe and a potentially deadly strain of the flu virus . An outside investigation by the U.S. Department of Agriculture found dangerous biological materials stored in unlocked refrigerators and a general lack of lab workers following safety protocols . Investigators say the anthrax that was believed to be deactivated was transferred in Ziploc bags , which are obviously not approved to carry such materials . `` This is troubling , and it is completely unacceptable , '' Murphy said . `` The CDC is supposed to be the gold standard ( for lab safety ) . ... This is not sound science , and this will not be tolerated . These practices put the health of the American public at risk . '' Murphy said the CDC was lucky that no one appears to have been infected during the anthrax incident , but `` sooner or later that luck will run out . '' This is not the first time the subcommittee has heard of safety issues at CDC labs , said Rep. Diana DeGette , D-Colorado . Multiple hearings over the past decade have shown lapses that together reveal a problem with safety reporting at the agency , she said . `` What we all need to know is the plan to change the culture at the CDC , '' DeGette said . `` We can do a lot but we ca n't legislate a culture change . '' Frieden , who took the CDC director job in 2009 , acknowledged that he and other CDC managers failed to recognize a `` critical pattern . '' The CDC has closed the labs that were involved in the incidents . They wo n't reopen until better safety procedures are in place , Frieden said . Scientists have also stopped moving any biological material out of its two highest-level labs while their procedures are being re-evaluated . This may slow some CDC processes -- such as providing materials for companies to create next year 's flu vaccine , Frieden said -- but safety comes first . `` We must do that work more safely , and we will , '' he said .
Executive Director Tom Frieden testified before Congress about anthrax incident . CDC needs to change its research strategy , congresswoman says . Frieden has closed the labs that were involved in the incidents .