THE DETAILS: Acute lymphoblastic leukemia (ALL) is the most common form of childhood cancer, attacking the body’s white blood cells and making it difficult for children to fight off infections. It’s generally diagnosed in kids between the ages of 3 and 7, and other than children with Down syndrome, who are 10 to 20 times more likely to contract ALL, there are no other identifiable risk factors.
The researchers for this study recruited 41 mothers whose children had been diagnosed with ALL as well as 71 mothers with healthy children, all of whom were from the Washington, DC, area. The average age of the children with ALL was 3 years old. The mothers filled out questionnaires asking about use of indoor pesticides, pet products, and lawn services, and how frequently they were exposed to these products currently, before conception, and during pregnancy. Both the mothers and children provided urine samples, which were sent off to a lab run by the U.S. Centers for Disease Control and Prevention for analysis.
Pesticide residues were detected in 99 percent of the urine samples, but the researchers found that levels of two specific pesticides were 25 percent higher in the children with ALL. Also, 33 percent of mothers of the children with ALL reported using pesticides, whereas only 19 percent of mothers in the healthy group did.
WHAT IT MEANS: The pesticides detected in this study fall into a class of chemicals called organophosphates, which have long been known to interfere with people’s nervous systems. Organophosphates make up 70 percent of the insecticides used in this country. They’re used on a variety of chemically grown fruits and vegetables, and they crop up in flea and tick products. Two forms of organophosphate pesticides have been banned for indoor use by the Environmental Protection Agency (EPA).
Although the EPA has banned some organophosphates in home pesticides, often the products themselves haven’t been tested for safety, says Warren Porter, PhD, professor of environmental toxicology at the University of Wisconsin, Madison, and Rodale.com advisor. And testing the products themselves, not just the individual components, is important, he adds. “The biological activity of the active ingredient is enhanced by the inert ingredients. Some inert ingredients are never tested in combination with the active ingredient.” For example, solvents that are in the product to help the active chemicals penetrate the waxy coating of a weed may also make it easier for the chemicals to enter the human body.
This study is the first confirming suspicions that organophosphates are linked to higher rates of certain types of cancer, and the findings aren’t surprising, says Porter. His research has found that pesticides interfere with the immune system and alter hormone levels. “Once you start messing with hormones and immune systems, you raise the risk of cancer,” he says, especially a form like ALL that attacks immune-system cells.
Limiting your exposure to organophosphate pesticides is a good idea, especially if you have children in the house. Here are a few places to start:
• Your front door. Studies have found higher levels of pesticides inside homes than outdoors—even in homes where pesticides aren’t used—
primarily because people track them in on their shoes. “You get pesticides on the soles of your shoes and then it dissolves in the waxes on your floors and in the fibers of your carpet,” says Porter. Adults who walk around barefoot, or kids who crawl on the floor, may absorb those chemicals through the skin. “Taking your shoes off at the front door is a critical first step,” says Porter. “Pardon the pun.”
• Your pets. Organophosphates are common in flea and tick products. Rather than collaring your pet with a band of chemicals, keep pests away using flea combs, regular bathing, and, as a last resort for bad tick problems, less-toxic chemicals. The Natural Resources Defense Council recommends Frontline, Advantage, and Revolution over the more hazardous flea collars and shampoos.
• Your fruits and vegetables. Common in chemical lawn and garden sprays, organophosphates can contaminate your homegrown produce. Porter recommends using vinegar sprays on weeds. “Vinegar destabilizes the waxy coating on plants that are sprayed with it, and they simply dry up and die,” he says. And be generous with the beneficial insects, which eat other bugs without destroying your plants. “Encourage wasps,” says Porter. “People think we’re crazy, but we’ve never had a problem with cabbage worms.”
• Your kitchen. “Anyone concerned about pesticide exposures ought to eat organic foods,” says Porter, citing studies out of the United Kingdom that have found at least 50 percent of foods sold in stores have measurable levels of pesticide residues. And in this study, the authors noted that the high levels of pesticides found in urine samples don’t match the relatively low levels of mothers who reported using pesticides in the home. “Chronic residential use and the heavy agriculutural use of these chemicals on crops, fruits, and vegetables continually expose humans to pesticides via the food chain, air, and water supply despite their short half-lives,” they write.
• Everywhere else. Most pest-control problems can be effectively controlled with integrated pest-management techniques, a method of pest control that involves finding the source of the problem (where the bugs are getting in) and either eliminating the food source or sealing their entry points. For a pest-by-pest guide to chemical-free elimination, visit the Integrated Pest Management Program at the University of California, Davis.