Yard Spray to Prevent Lyme Disease Flunks Out
Lyme disease, a bacterial illness transmitted by the bite of a deer tick, is a major health concern in the Northeast and Mid-Atlantic regions. Health agencies are keen to prevent it, but some people believe that a government program to do so might be worse than the illness. The story is another example of how seemingly good ideas in medicine don't always pan out.
As reported last month in the Baltimore Sun, hundreds of Baltimore-area families who volunteered for a government study to spray their suburban yards with pesticide might be at risk. The chemical in the spray, bifenthrin, is classified by the Environmental Protection Agency (EPA) as a possible carcinogen.
Critics of the program note that the EPA is studying bifenthrin for possible harm to reproductive and immune systems. They say that prospective volunteers weren't well enough informed about the potential long-term health risks from being exposed to the pesticide.
Lyme disease can cause fever, headaches, fatigue and, if untreated, can affect the joints, nerves and heart. It’s nasty business. But, say critics of the three-state study underwritten by the Centers for Disease Control and Prevention (CDC), so is exposure to a dangerous pesticide.
Half of the families who signed up for the study have the edges of their yards sprayed with the pesticide commonly applied around homes to fight ticks, fleas and mosquitoes. The others’ yards are sprayed with water. The residents don’t know if they’re recipients of chemicals or mere H2O.
Dr. Clifford S. Mitchell of the state Department of Health and Mental Hygiene explained the study. "The question is, does it actually prevent a common, sometimes severe disease — and second, what's the lowest dose you can do?"
Jay Feldman of Beyond Pesticides, a nonprofit that works toward eradicating toxic pesticides, says that federal and state health officials have not adequately informed volunteers about all the potential health risks. "It's improper to be conducting a human experiment like this."
The Sun reports that an EPA analysis of bifenthrin cites nearly 1,300 incidents involving the pesticide from 2002 to 2009. Most were of "low severity," but even low amounts of the chemical can cause skin and respiratory irritation and dizziness.
The agency classifies it as a possible carcinogen based on rat exposure studies. It also has listed bifenthrin among a group of pesticides to be tested for their potential to act as "endocrine disruptors," which may affect humans or wildlife, even at low doses.
According to the CDC, 30,000 cases of Lyme disease were reported in 2010, most in the regions of study. Health officials believe that doctors often miss or don't report cases, so the actual number could be significantly higher.
Study volunteers were recruited via fliers mailed to residents in ZIP codes with a high incidence of Lyme disease. They sought people who were willing to have a "single, no-cost, commonly used pesticide application" to their yard and answer "short surveys" about ticks and their yards.
Health officials advised study participants not to walk in the sprayed area for 24 hours and to keep pets away. The chemical is highly toxic to aquatic life, so no yards within 100 feet of water are being tested. They say the study and the volunteer information was approved by state and federal review boards whose function is to safeguard people participating in research.
So, does bifenthrin work?
Preliminary results for all three states from the first year of the study indicate that the yards treated with pesticide had 62 percent fewer ticks overall than the yards sprayed only with water.
But residents of the treated households found just as many ticks on their bodies as the residents of untreated properties. And—here’s the money stat—essentially the same number of Lyme disease cases were reported in both groups.
Health officials say that if a second year’s analysis yields no difference in tick bites or infection between the two groups, they'll advise the public that spraying yards with pesticide doesn't help prevent Lyme disease.
But critics say such an outcome — discouraging more pesticide use — would not justify the risks the human subjects assumed. Said one, “We have no idea if we've caused more harm than good.”
According to the National Institutes of Health, (NIH) symptoms of Lyme disease begin days or weeks after infection.
They are similar to the flu and may include:
- body-wide itching;
- light-headedness or fainting;
- muscle pain;
- stiff neck;
- a "bull's-eye" rash, a flat or slightly raised red spot at the site of the tick bite. Often there is a clear area in the center. It can be quite large and expanding in size.
If the disease isn’t treated at this stage, it can progress and express more dire symptoms, such as facial paralysis, joint and speech problems, heart palpitations and numbness.
To prevent Lyme disease, the NIH recommends taking precautions to avoid direct contact with ticks. Be extra careful during warmer months. Also:
- Avoid wooded or bushy areas, or areas with high grasses and leaf litter.
- Walk in the center of trails.
- Check yourself and your pets frequently during and after your walk or hike.
- When walking or hiking in wooded or grassy areas, spray all exposed skin and your clothing with insect repellant.
- Treat clothing, such as boots, pants, and socks, with a product containing permethrin, which remains protective for several washings.
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