Hundreds of abandoned vials labeled with names such as "dengue," "influenza" and "Q fever" were discovered in a lab on the campus of the National Institutes of Health (NIH), the government disclosed Wednesday.
The discovery marks what appears to be the latest in a troubling string of safety lapses at government health agencies. Other breaches have involved anthrax, avian flu and smallpox.
Pressure is mounting for agency heads to explain the incidents, and lawmakers are increasingly skeptical that current safety procedures are working well.
Federal health officials said there is no evidence anyone was exposed to the biological agents.
They could not say Wednesday how many vials in the latest unearthing actually contained viruses or whether the vials' contents were dangerous or lethal.
"This is matter that is currently under review," said Karen Midthun, director of the Center for Biologics Evaluation and Research at the Food and Drug Administration (FDA).
"We are obviously reviewing all of our policies and procedures to determine what corrective actions are necessary."
The vials have been transferred to the Department of Homeland Security for safekeeping, according to the FDA, which runs the lab where the discovery took place.
"Testing for these unlabeled vials is in progress … and could take as long as two weeks to find whether they contain hazardous materials," Midthun said.
The disclosure came a week after the NIH revealed that six vials of the smallpox virus were found abandoned in cold storage on its campus.
At that time, the agency did not say that a total of 12 boxes containing 327 carefully packaged vials had been found in the lab, including those marked with names like "dengue."
As previously reported, the vials of smallpox and 10 with unclear labeling were sent to a high-security facility in Atlanta run by the Centers for Disease Control for examination and eventually, destruction.
Another 32 were destroyed at the NIH facility. The remaining 279 samples went to DHS.
FDA officials said they are "actively trying to assess" why the boxes of vials went overlooked for roughly half a century.
The collection was most likely assembled in the 1940s, 50s 60s when safety standards for biological specimens were "very different from those used today," according to a memo from the agency.
—This post has been updated.