Researchers who work with disease-causing pathogens and biological toxins at U.S. biodefense labs should undergo more frequent security screening, according to a federal advisory panel. A report by the Working Group on Strengthening the Biosecurity of the U.S. recommends that personnel with access to the deadly materials should undergo an evaluation every three years instead of every five, as currently required, as well as random drug testing. The panel also suggests more scrutiny of foreign nationals who work in U.S. labs. The working group was established by former president George W. Bush at the end of his second term after the FBI concluded that an Army scientist, Bruce E. Ivins, was most likely responsible for the 2001 anthrax attacks that killed five people. The group's recommendations for heightened personnel security measures echo some of the proposals included a Senate bill (S. 1649) that would require the Department of Homeland Security to issue security regulations for the country's biological research facilities.