A new study in Pediatrics has made a connection between exposure to organophosphates – pesticides used on berries and other fruit and vegetable crops – and Attention Deficit/Hyperactivity Disorder (ADHD) in children.1
Organophosphates kill agricultural pests by acting as neurotoxins in insects. Excessive exposure to organophosphates in humans are now known to have toxic effects. Children are thought to be most vulnerable because the developing brain is especially susceptible to neurotoxic substances. Organophosphate exposure during fetal development and the first 2-3 years of life has previously been linked to detrimental effects on neurodevelopment in young children, including behavioral problems and deficits in memory and motor skills.1,2 High levels of organophosphate metabolites have also been found in children with leukemia.3
Since dysfunctional acetylcholine signaling is thought to be involved in ADHD, and organophosphates act by disrupting acetylcholine signaling, scientists decided to investigate a possible link between organophosphate exposure and ADHD. The researchers pulled data from the National Health and Nutrition Examination Survey (2000-2004) on urinary metabolites of organophosphates in children 8-15 years of age.
Their findings showed that children with higher than median excretion of dimethyl thiophosphate, the most common of the organophosphate metabolites, had double the risk of ADHD compared to children with limits below detection. This result is alarming, because it suggests that levels of organophosphate exposure common among U.S. children are capable of promoting ADHD – not just the highest levels of exposure.1
How are children exposed to organophosphates?
Since organophosphates are commonly sprayed on many agricultural products (including corn, apples, pears, grapes, berries, and peaches), diet is the major source of organophosphate exposure in children. Insecticides used in and around the home are also potential sources, but diet is believed to be predominant. Forty different organophosphate pesticides are currently in use in the U.S., and based on 2001 estimates 73 million pounds of organophosphates are used per year.1
In 2008, the USDA conducted tests that found malathion (one of the 40 organophosphate pesticides) residues in 28% of frozen blueberries, 25% of strawberries, and 19% of celery.1 The Environmental Working group has found that commercial baby food is the predominant source of organophosphate exposure in infants 6-12 months of age. For young children, the most common culprits are apples, peaches, applesauce, popcorn, grapes, corn chips, and apple juice.4
What can you do to limit exposure?
A study that switched children from conventional to organic foods found a dramatic decrease in urinary metabolites of organophosphates.5 You can reduce your (and your children’s) exposure to organophosphates and other potentially harmful pesticides by buying organic produce whenever possible, especially when buying foods that are most heavily laden with pesticides – celery, strawberries, blueberries, peaches, apples, and grapes rank among these high-pesticide crops.
Read more about choosing produce wisely to minimize your family’s exposure to pesticides.
1. Bouchard MF, Bellinger DC, Wright RO, et al. Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides. Pediatrics 2010;125:e1270–e1277
2. Harari R, Julvez J, Murata K, et al. Neurobehavioral Deficits and Increased Blood Pressure in School-Age Children Prenatally Exposed to Pesticides. Environ Health Perspect. 2010 Feb 25. [Epub ahead of print]
Jurewicz J, Hanke W. Prenatal and childhood exposure to pesticides and neurobehavioral development: review of epidemiological studies. Int J Occup Med Environ Health. 2008;21(2):121-32.
3. Fallon Nevada: FAQs: Organophosphates. http://www.cdc.gov/nceh/clusters/Fallon/organophosfaq.htm
4. Environmental Working Group. Overexposed: Organophosphate Insecticides in Children’s Food. http://www.ewg.org/book/export/html/7877
5. Lu C, Toepel K, Irish R, et al. Organic diets significantly lower children's dietary exposure to organophosphorus pesticides. Environ Health Perspect. 2006 Feb;114(2):260-3.