Mar. 24, 1999 ANAHEIM, Calif., March 23 -- Clothes may soon be able to protect agricultural workers, or even weekend gardeners, from more than the sun. Scientists at the University of California in Davis say they have made cotton fabrics with built-in pesticide detoxifiers. They add that clothes made with the new material could be cleaned and the detoxifying chemicals reactivated simply by washing them with bleach. The development was detailed today at a meeting of the American Chemical Society, the world's largest scientific society.
Past studies report that up to 97% of pesticides entering the body do so through the skin. Currently, workers exposed to high levels of pesticides must wear synthetic materials to block entry of pesticides. Because such clothing does not allow entry of air, they create heat stress. Workers exposed to lower levels of pesticide, therefore, have to choose between comfort and protection. In addition, today's protective clothing must be discarded after use, which can be costly and create additional environmental concerns.
"I had a chance to go to some of the strawberry fields in California," says University of California graduate student Louise L. Ko, "and you'd be surprised to see the harvesters just wear regular denim jeans and t-shirts," rather than wear the uncomfortable protective gear.
Ko and UC faculty advisor Gang Sun, Ph.D., decided to go beyond blocking the pesticides, trying instead to decompose them on contact. They grafted a chemical compound, called a hydantoin, to the surface of common cotton/polyester fabrics. Ko hoped "it would be breathable and comfortable, as well as giving (the field workers) some kind of protection." When armed with a chlorine atom and exposed to certain pesticides called carbamates, she says the activated compound "breaks down the pesticide into smaller, unharmful fragments."
After a day's work, garments made by this process could be tossed in the wash with chlorine bleach. "The small fragments will be washed away during the regular laundry process and, along with that, the active sites will be regenerated by the bleach," says Ko.
In laboratory tests, treated textiles took less than five minutes to degrade some carbamate pesticides by as much as 99%. Ko cautions, however, that this treatment has not been tested against organophosphorus pesticides, which account for a large portion of currently used pesticides.
Both carbamate and organophosphorus pesticides are used on a wide variety of field crops, such as corn and cotton, as well as on fruits vegetables. In 1995, the University of California says use of the carbamates aldicarb and methomyl in that state were most often on cotton and lettuce respectively. The organophosphorus pesticide malathion was most commonly used on alfalfa and strawberries.
Interestingly, the same chlorine-armed halamine compound that works against carbamate pesticides also seems to work as an antibacterial agent. The process to create the protective clothing has been patented and the technology purchased by Halosource Corporation of Seattle, Washington. This research was funded, in part, by the National Science Foundation.
A nonprofit organization with a membership of nearly 159,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.
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