Smarter Living: Family Health
Higher Organophosphate Pesticide Levels Linked to ADHD
Photo: Old Shoe Woman
In a representative sample of US children, those with higher levels of organophosphate (OPs) pesticide metabolites in their urine were more likely to have attention-deficit/hyperactivity disorder (ADHD) than children with lower levels, researchers report in the June, 2009 issue of Pediatrics.
"Each 10-fold increase in urinary concentration of organophosphate metabolites was associated with a 55 percent to 72 percent increase in the odds of ADHD," says lead study author Maryse F. Bouchard, PhD, of the Department of Environmental and Occupational Health, University of Montreal. ADHD is characterized by inattention, impulsivity and hyperactivity to the degree that the child has an impaired ability to learn and function at home and at school. About three to seven percent of school-aged children suffer from ADHD, according to the Centers for Disease Control and Prevention (CDC). The disorder tends to run in families, so genetics plays an important role. Prenatal exposure to lead and environmental tobacco smoke are also potential culprits, as is alcohol use during pregnancy.
Previous investigations of pesticides have focused on special groups with high levels of exposure, such as children from agricultural communities, and reported pesticides-related cognitive deficits (involving memory and attention), and behavioral problems. "This is the first study to link exposure to pesticides at levels common in the general population with adverse health effects," noted Dr. Bouchard but cautioned that "These findings should be replicated before strong conclusion can be made."
How Might OPs and ADHD be Linked?
Several biological mechanisms might underlie an association between organophosphate pesticides and ADHD. It is well established that organophosphates disrupt neuro-chemical activity in the brain. In particular, organophosphates disrupt the activity of acetylcholine, a neurotransmitter that ensures that the chemical signal that causes a nerve impulse is halted at the appropriate time. These changes in brain activity could well result in ADHD-like symptoms.
Dr. Goldstein, a specialist in child neurology with Western Neurological Associates in Salt Lake City, Utah, said the data on organophosphate pesticides and ADHD are similar to the data being developed 30 to 40 years ago with lead exposure, and it may turn out to be the same thing--that even small exposures (to organophosphate pesticides) are very harmful to kids.
How Are We Exposed?
People are commonly exposed to OP pesticides through eating fresh and processed vegetables, contacting pesticide-contaminated surfaces, breathing air near pesticide applications (both indoors and outdoors), and drinking pesticide-contaminated water.
Approximately 40 organophosphate pesticides are registered with the US Environmental Protection Agency (EPA). About 70 percent of insecticides (pesticides that kill insects) used in the United States are OP pesticides.
Peaches, apples, grapes, green beans, and pears are among those fruits and vegetables that are conventionally grown with OP pesticides and are most commonly eaten by children, according to FoodNews.org. A 2008 US study revealed detectable concentrations of the organophosphate malathion in 28 percent of frozen blueberry samples, 25 percent of strawberry samples, and 19 percent of celery samples.
Other top uses of OP pesticides include corn, cotton, wheat, other field crops, and for termite and mosquito control. Certain pest control products for cats and dogs contain OP compounds.
OPs of primary concern include: azinphos-methyl (product name Guthion,chlorpyrifos (products Lorsban and Dursban), diazinon (product name Spectracide), dichlorvos (DDVP), dimethoate, thephon, malathion, methamidophos, naled, and oxydemeton-methyl.
Residential uses of chlorpyrifos and diazinon were recently banned by the U.S. Environmental Protection Agency (EPA). Detailed information on specific OP pesticides is available at the Agency for Toxic Substances & Disease Registry.
How Can WeLlimit Exposure?
Because of the known dangers pesticides pose to humans, the U.S. EPA limits how much residue can stay on food. But "the new study shows it's possible even tiny, allowable amounts of pesticide may affect brain chemistry," warns Virginia Rauh, a PhD at Columbia University’s Center for Children’s Environmental Health who has studied prenatal exposures to pesticides. It seems prudent, therefore, to reduce pesticides exposure by reducing their use in agriculture.
Consumers can limit their exposure by:
Choosing organic produce, including frozen organic produce. A 2008 Emory University study found that in children who switched to organically grown fruits and vegetables, urine levels of pesticide compounds dropped to undetectable or close to undetectable levels.
Checking the labels on any older pest control or gardening products in your household to make sure they do not contain chlorpyrifos (or Dursban, its trademarked name). If they do, contact your sanitation department for information on how to dispose of it as household hazardous waste, or check Earth911.org for information on hazardous waste disposal in your area.
Checking the label on pet care products. Avoid flea collars that list propoxur, tetrachlorvinphos, amitraz or carbaryl as active ingredients. Instead, read How to Control Fleas Without Chemicals for safer pet care advice; give your pet regular baths with a pesticide-free pet shampoo, and use a flea comb between baths; launder your pet’s bedding in hot water, and vacuum carpets regularly to eliminate flea eggs that could be hidden there. If you do need to use a chemical flea-control product, choose the safest options as suggested in our GreenPaws Product Directory. Those dispensed in pill form usually contain the least toxic chemicals, and won’t leave a residue on your pet or in your home.
last revised 12/30/2011