Congressional investigators have found alarming weaknesses in security procedures at two top laboratories that work with the world’s most dangerous biological agents and diseases. As the country races to open more labs to develop vaccines and treatments for exotic diseases and potential biological weapons, the government clearly has a lot more work to do to ensure that dangerous materials cannot fall into terrorists’ hands.

The Government Accountability Office evaluated perimeter security at all five of the country’s so-called Biosafety Level 4 facilities. These are the only labs allowed to work with pathogens for which there is no cure or treatment, such as the Ebola virus and smallpox.

Three of the labs had all or nearly all of the 15 security controls that the G.A.O. deemed important. The other two  one reportedly operated by the Southwest Foundation for Biomedical Research in San Antonio, the other by Georgia State University in Atlanta  lacked the vast majority of the recommended controls.

Although the Centers for Disease Control and Prevention, which regulates the facilities, contends that security differences stem from the different level of risk at each site, the defects identified are hard to defend.