Worries about CDC pathogen handling

are designed to operate under negative air pressure, which keeps germs in by having air flow only in one direction. Air is constantly drawn from clean areas and halls into the lab, then vented outdoors through specially designed HEPA filters. The incident that led to CDC lab workers having their blood tested began around 3 or 4 a.m. on 25 May 2007. This is when CDC facilities staff shut down the building’s air handling system for maintenance, said Bowen. After the system was restarted, the Q fever lab lost its negative air pressure. When workers arrived to begin their day, they discovered air coming out of the Q fever lab, rather than going into it, CDC officials said. “It pulled air out of that lab and into that corridor,” Bowen said.

The Q fever lab is somewhat unusual in its design, CDC officials acknowledge. To allow safe viewing of scientists’ work with Q fever bacteria and infected mice from a “clean” hallway, there typically would be a sealed glass window. The lab, however, has a door next to the window. Although it is locked and not used, it has no special seals along its edges, and allows the flow of air when not sealed with duct tape. Seals are not required on BSL-3 lab doors, CDC emphasized. The door was put there to increase the flexibility of the lab space, enabling it to someday be used for lower-level experiments that don’t require stringent BSL-3 precautions. After the May 2007 incident when air was drawn out of the lab, the agency applied duct tape around all of the door’s edges as an added safeguard to control airflow.

Bowen and other CDC officials said there have been no other incidents where potentially contaminated air has blown out of the Q fever lab because air pressure changed from negative to positive. An inspection report written by a CDC animal lab consultant in March 2007, however, states: “Bldg. 18 — positive airflow from the Q fever laboratory into the clean hallway … The door into the corridor was taped temporarily and did not adequately contain the airflow into this corridor. This issue must be corrected immediately to ensure the health and safety of personnel and research chimpanzees.” The consultant, Bradford Goodwin Jr., declined AJC’s requests to be interviewed. Goodwin, a veterinarian, is executive director of the Center for Laboratory Animal Medicine and Care at the University of Texas Health Science Center in Houston. CDC officials said the duct-taped door that Goodwin cited in his report is a different door from the one that currently has tape on it. They said there was no positive air-flow problem - where air moved out of the lab — in March 2007. “He misunderstood the fact that the door separated two clean corridors and therefore that resulted in misinformation being included in the report,” said Skinner, the CDC spokesman. Skinner noted the Q fever lab didn’t go “hot” and begin conducting experiments until two months after Goodwin’s visit. CDC officials agree, though, that duct tape was on the door mentioned in Goodwin’s report. “This door was duct-taped as a means to stop entry and exit until an appropriate lock could be installed and to limit air transfers between the two clean corridors,” CDC officials said in a written statement. Some experts said it is difficult to gauge the significance of the duct tape on the lab doors without more information. “It could be inconsequential or it could be consequential,” said Chris Newcomer, executive director of the Association for Assessment and Accreditation of Laboratory Animal Care International, commenting in general and not about CDC’s lab in particular.”There’s nothing intrinsically dangerous about duct tape or repair with duct tape on the seal of a door,” Newcomer said.