Dust Defeats Germ-Killing Fabrics

NEWPORT NEWS, VA, Sept. 24 -- While researchers have found many ways to make fabrics that kill germs in the lab, the first field study of germ-killing fabric reveals that the real world is a tougher place.

Contaminants, such as dust and spilled coffee, can coat the surface of a germ-killing fabric and allow germs to thrive, according to research performed at the Department of Energy’s Thomas Jefferson National Accelerator Facility.

Products promising to eliminate germs are ubiquitous – from antibacterial sponges to germ-free doorknobs. Now germ-killing, or antimicrobial, fabrics are being designed to, for instance, protect patients from germs clinging to caregivers’ clothes and reduce first-responders’ exposure to germs used in bioterrorism.

Michael Kelley, a joint Jefferson Lab/College of William & Mary researcher, was a member of a DuPont team that developed a germ-killing nylon by using ultraviolet light. In lab tests, the "killer nylon" eradicated common germs, such as E. coli.

Under a $192,000 grant from the Department of Homeland Security, Kelley and a colleague, Olga Trofimova, recently tested the nylon's ability to kill germs in the real world. The scientists placed samples of the fabric in police squad cars and ambulances, and in police and fire departments for 70 days. Then the researchers exposed the fabrics to germs. They found that germs thrived. In fact, the germs grew 100 to 1,000 times more in number than those on ordinary and unexposed fabric.

Kelley speculates that dust protected germs from the fabrics' germ-killing surface.

"Microbes grow on the dust. And now, because you have all this dust on the fabric, instead of killing the microbes, they have a happy home and grow well on it," he says. "Moreover, the problem we've uncovered faces every antimicrobial fabric, not just our nylon. Our next step is to see how much it really matters – people wash their clothes more often than every two months. The question is: How often do we have to wash it to make sure it's adequately free of dust?"

The researchers also tested the nylon's ability to weather common substances, such as coffee, salad dressing and detergent. The fabrics held up to laundering, but coffee, salad dressing and some other common substances sapped the fabrics' ability to kill germs.

"We had hoped that we could simply make upholstery, drapes and so on with antimicrobial fabrics, but that's not going to work so well. We think we can instead make antimicrobial garments that, with the right care, can be used again and again," Kelley says.

Jefferson Lab is managed and operated by the U.S. Department of Energy's Office of Science by Jefferson Science Associates, LLC, a joint venture between Southeastern Universities Research Association, Inc. and CSC Applied Technologies Division, LLC.