Treatment makes cotton permanent-fresh.

A simple and inexpensive treatment makes fabrics lethal to odor- and disease-causing bacteria, says Jeffrey E Williams of HaloSource Corp. in Seattle. Such antimicrobial textiles could find uses in sportswear, towels, hospital gowns, and bandages.

Williams and his colleagues grafted compounds called N-halamines to cotton fibers with a process developed by Gang Sun of the University of California, Davis. The method resembles that used to give fabrics a permanent-press finish by binding resin to cotton. In the new method, the N-halamines hold onto chlorine atoms that then kill any microorganisms the fabric contacts. The researchers report that after 2 minutes on treated cloth, the detectable number of microbes on the fibers drops from 1 million to zero.

The team even conducted a smell test with the help of 10 brave volunteers. Williams and his group placed cat urine and bacteria on treated and untreated fabric. This foul combination "generates ammonia in prodigious amounts within minutes," says Williams. After 4 hours, the smell of the untreated fabric caused volunteers to gag and cough, whereas the treated fabric gave off only a light chlorine odor.

The grafted N-halamines stay on the fabric for at least 50 washes, Williams says. A dilute bleach rinse refreshes the molecules with chlorine and restores their antimicrobial activity. Such fabrics could help prevent the transmission of disease in hospitals and may be useful for burn victims, who are especially vulnerable to infection.