skip to main content

→ Top Stories:
Clean Power plan
Safe Chemicals

Gina Solomon’s Blog

New Studies Show Long-Term Harm to Children from Common Pesticides

Gina Solomon

Posted April 21, 2011

, , , , , , ,
Share | | |

Scientists are usually too cautious to say they have "proven" anything. Instead, they use terms like "identified an association", "linked", and other cautious science-speak. But three studies published online side-by-side in today's edition of the journal Environmental Health Perspectives come about as close as I can imagine to absolute proof.

Three groups of top-notch researchers, conducting three independent studies, including a total of nearly 800 children from New York and California, all found the same thing: Maternal exposure to certain pesticides during pregnancy predicts neurological deficits in children during childhood. The scientists found that the children with higher exposure to these pesticides had lower IQ, poorer working memory, and diminished perceptual reasoning. Working memory measures the ability to concentrate, memorize information, hold on to those memories, and retrieve the information from memory. Perceptual reasoning is the ability to use non-verbal information (such as pictures) to make logical inferences. In other words, the children with higher pesticide exposures were significantly hindered in their ability to excel in school and in life.

The pesticides at issue are called organophosphates. These chemicals are common insecticides and they have been in use since the 1940’s when they were derived from nerve warfare agents. They have long been known to be highly toxic to the nervous system, but their dramatic effects on the development of the brain were not appreciated until about 15 years ago, when studies in laboratory animals began to reveal profound effects on the development and migration of neurons in the infant brain. Early findings from human studies found surprisingly widespread exposure to these chemicals, and strong hints of neurological effects. So these new findings, in children aged 6-9 years, confirm a lot of prior evidence and demonstrate that the effects on the brain don’t simply disappear with time.

A decade ago, the EPA took a bold and necessary step by banning two organophosphate pesticides (chlorpyrifos, otherwise known as ‘Dursban’, and diazinon) from use indoors. That means that children today aren’t being exposed to these chemicals from roach killers, flea bombs, and other household pesticides. That’s a big step forward for children’s health and EPA deserves the gratitude of all parents of young children for getting these chemicals out of our homes.

Unfortunately, there are two remaining problems. The first is that a couple of related chemicals (tetrachlorvinphos and propoxur) are still legally allowed in flea collars for pets. NRDC researchers identified high residues of these chemicals on the fur of dogs and cats wearing these collars, putting pet owners at risk. Second, these pesticides are still widely used in agriculture, putting farmworkers, agricultural communities, and food consumers at risk.

Ten years ago, when EPA essentially made the bargain with the pesticide industry to allow most agricultural uses of organophosphates in exchange for the cancellation of household uses, it seemed like a good deal. (It probably was a good deal, since household uses did account for major exposures). But since that time, numerous studies have shown that – at least in children – most of their exposure to these chemicals now comes from food. The amounts of these chemicals that many children get from food are quite significant – in the range of the levels that may affect brain development. What’s more, researchers have had families switch temporarily to a diet containing organic fruits and vegetables and demonstrated that the levels of these chemicals in children’s urine plummets to near-zero. [If you're interested in reading more about the effects of an organic diet, the actual studies are here, here, and here.]

So which foods have the highest residues of toxic pesticides? If you only have a limited budget to buy organic food, here are the foods to spend your money on: 

  • Strawberries
  • Cherries
  • Peaches and nectarines
  • Apples
  • Pears
  • Cantaloupe
  • Bell peppers
  • Lettuce
  • Celery
  • Tomatoes
  • Green beans
  • Peas
  • Cucumbers

There's more information in the Organic Center's Organic Shopping Guide, and EWG's Shopper's Guide to Pesticides. But this isn't a problem that consumers should have to shop their way out of. The government should protect us. That's why NRDC petitioned EPA in 2007 to deal with the dangerous food uses of the pesticide chlorpyrifos. As part of a settlement of the subsequent NRDC lawsuit, EPA is scheduled to release an updated assessment of the health risks of chlorpyrifos by June of this year. The new studies that were released today need to be incorporated into that assessment, and EPA needs to take action to assure that mothers and children are protected from dangerous chemicals on food.

Share | | |


Gina Solomon, MD, MPHApr 21 2011 01:32 PM

I just found out about this great resource for consumers! A website maintained by the Pesticide Action Network of North America called "What's on my Food?". Check it out if you're trying to figure out which foods to buy organic, and as a great resource for learning about all these issues:

James T.Apr 24 2011 08:19 AM

A recent study found that prenatal exposure to pyrethroids -- a class of pesticide found in many household pest products -- may also impair the mental development of children:

Comments are closed for this post.


Switchboard is the staff blog of the Natural Resources Defense Council, the nation’s most effective environmental group. For more about our work, including in-depth policy documents, action alerts and ways you can contribute, visit

Feeds: Stay Plugged In