RODALE NEWS, EMMAUS, PA—Among the many dangers of pesticides already known are cancer, non-Hodgkin's lymphoma, and Parkinson's disease. Now you can add obesity and type 2 diabetes to the list. A new study published in the Journal of Medicinal Chemistry finds that a certain class of chemical pesticides used on lawns can influence your body's secretion of insulin, which could have a long-term impact on your waistline.
THE DETAILS: The researchers used human tissue cells to see how they were influenced by two classes of chemicals, phenoxy herbicides and fibrates. Phenoxy herbicides are a large class of chemical pesticides encompassing 2,4-D, the most widely used pesticide in the U.S. and the active ingredient in most "weed and feed" fertilizers and products like Ortho Weed-B-Gone; fibrates are cholesterol-lowering drugs. They found that both phenoxy herbicides and fibrates block the body's receptors of a particular hormone, T1R3, found on your tongue and in your pancreas, that regulates your body's ability to sense sweet tastes. It also influences your body's ability to produce insulin.
The reaction is similar to what might happen if you go on a high-carbohydrate diet, says study coauthor Bedrich Mosinger, MD, PhD, a geneticist and researcher at the Monell Chemical Senses Center in Philadelphia. "High-carb diets stimulate your pancreatic cells, and insulin releases more quickly," he says. That, in turn, lowers your blood sugar and makes you crave, and eat, more food. "Chronically, when you do that, it depletes the body's ability to produce insulin. Eventually, people cannot make enough insulin to sustain blood glucose levels, and that results in type 2 diabetes."
WHAT IT MEANS: A test-tube study doesn't prove that the same thing would happen in the human body. But the chemical pesticides you use on your lawn may be influencing your body's ability to regulate insulin production, and the potential for it to lead to bigger problems like obesity and type 2 diabetes is very real, says Dr. Mosinger. "Anything that can disturb your body's hormonal regulation can have a significant effect," he says. He's currently studying how these chemicals work on human bodies, not just tissue. "What we're finding is that the sweet receptors on your tongue are also on many endocrine cells," he says, and these endocrine cells play a large part in how your body regulates hormones, including insulin and thyroid hormones that influence weight.
Used to some degree in agriculture on wheat and rice crops, 2,4-D and other phenoxy herbicides are more widely used on lawns and gardens, where they wash off into storm drains and eventually into rivers and streams that feed drinking-water supplies. As with most pharmaceuticals, fibrates end up in water after they pass through your system and go down the toilet. "Many of these herbicides and fibrates are not removed by water treatment," Dr. Mosinger says. Studies have also found that 2,4-D can blow into homes and linger in household dust that you inhale. "The concentrations that are currently in the environment are in the parts-per-billion range, not extremely high," he says, adding that the concentrations at which long-term damage can be done are unknown at this point. "An acute exposure probably would not make that much of a difference," he says, "but chronic exposure can have an impact on type 2 diabetes."
Protect yourself and your blood sugar levels by taking a few steps to limit your exposure:
• Get a water filter. Standard faucet-mount or pitcher filters that use carbon or charcoal are sufficient to remove 2,4-D from your water. There's some evidence that they also remove pharmaceuticals, such as fibrates, although their effectiveness on those compounds isn't fully known at this point.
• Switch to organic lawn care. Weed control doesn't require dousing your grass with pesticides. In fact, your weeds are probably trying to tell you about a problem you can fix without toxic chemicals. For instance, clover is a sign that your lawn is too low in nitrogen, and brown grass means you're mowing too much, not that it needs more fertilizer. For other organic solutions, check out our story on chemical-free fixes for common lawn problems.