Bad buy: If it's labeled "anti-odor" or "antimicrobial," put it back on the rack.

RODALE NEWS, EMMAUS, PA—The next time you reach for that anti-odor shirt, consider the findings of a new study published in the journal Environmental Science & Technology. Swiss researchers tested a bunch of clothes that contained silver nanoparticles, metal particles shrunk down to sizes one billionth of one meter thin, put there to prevent odor-causing bacteria from proliferating while you sweat. They found that most of the treatments in these antibacterial products came out in the wash after only two launderings—wasting your money, and releasing a material into rivers and streams that's toxic to fish and other aquatic life.

THE DETAILS: Swiss researchers tested nine commercially available textiles, made from cotton, polyester, nylon, Spandex, and other synthetics, that contained silver nanoparticles. Some of the fabrics were washed in detergent alone, others in detergent and bleach, after which the scientists analyzed the wastewater to see how much of the nano-scale silver had migrated out of the clothing. Four of the fabrics lost between 20 to 35 percent of their silver nanoparticles after two washes, but one fabric lost more than half. Fabric that was washed in both detergent and bleach released fewer silver nanoparticles than fabric washed in detergent alone, but, the authors suspect, those results may be skewed by the fact that the chemical reaction between silver, bleach, and detergents may have masked the amount of silver released from the clothing.

Read on for nontoxic anti-odor tactics.