A government funded study shows that weed killers and other pesticides applied to lawns can be tracked into homes by people and pets up to a week after treatment, causing unnecessary exposure, particularly to children. By taking commonsense steps such as removing shoes before entering the house and restricting youngsters and pets from lawns following application, consumers can substantially reduce track-in, concludes the study.
Results of the study, involving application of the herbicide 2,4-D to the lawns of 13 homes in the Columbus, Ohio, area, are scheduled to appear in the May 1 print issue of the peer-reviewed journal Environmental Science & Technology, published by the American Chemical Society, the world's largest scientific society. The research was initially published on the journal's web site on March 31.
The study was done by Battelle Memorial Institute laboratories in Columbus and is one of several being sponsored by the U.S. Environmental Protection Agency's National Exposure Research Laboratory in Research Triangle Park, N.C., to assess the potential exposures of small children to pesticides used in and around the home.
The measurement of pesticide levels in the Ohio houses is the first actual in-home proof that 2,4-D can be tracked into residences up to a week after application to lawns. The scientists had previously predicted the track-in based on simulation studies.
Rooms with carpeted floors, when compared to bare floor areas, generally had higher levels of tracked-in 2,4-D, according to the journal article. In homes with bare floor entryways, the highest levels of the herbicide were found in carpeted living rooms and bedrooms. In homes with carpeted entryways, the levels were higher there than in other parts of the house.
Having a rug or carpet in the entryway of the house helps "limit the further migration of those residues into the living areas of the home where children are more likely to play on the floor," says the report's lead author, Marcia Nishioka, M.S., a senior research scientist at Battelle.
The results of the study show that it may be fairly straightforward to limit indoor exposure, says Nishioka. "The important message here is that track-in of herbicides and pesticides from the lawn can be limited by simple control procedures," she says. "The consistent removal of outdoor shoes at the door by both the homeowner applicator and children, or the use of a commercial applicator, can reduce the levels brought indoors. Carpeting at the door, rather than a bare floor there, can be used to catch the residues that do enter."
Restricting the access of indoor-outdoor pets to recently treated lawns and wearing coveralls when applying lawn treatments and then removing the protective clothing before entering the house are two other effective ways of preventing track-in, according to the journal article. In humans, contact with 2,4-D can cause skin rashes, dermatitis and irritation to the gastrointestinal tract, according to EPA's hazard summary for the herbicide. However, "the long-term chronic health effects of 2,4-D are unknown at this time," says Nishioka.
"Residential exposure to pesticides may increase the potential health risks to all humans, but such risks are considerably greater for infants and toddlers, who frequently crawl or lie on the floor, may have intimate contact with family pets, and mouth their toys and other objects that may contain chemical residues," says EPA senior scientist Robert G. Lewis, Ph.D., study manager and co-author of the paper.
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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