Women's  Healthcare Topics is a website about pregnancy and your newborn baby.

Pesticide Exposure May Be Linked to ADHD

Reviewed by James Brann, M.D.

Attention Deficit Hyperactivity Disorder

Learn about the link between pesticide exposure in pregnancy and ADHD.

In the past decade, scientists have suggested a potential link between environmental factors (such as cigarette smoking and drinking alcohol) during pregnancy to your child's risk of developing attention deficit hyperactivity disorder (ADHD). Research on the cause of ADHD is ongoing, but scientists have now targeted another common environmental hazard to the list of potential causes of ADHD - pesticide exposure during pregnancy.

A new study, published in the August 2010 issue of Environmental Health Perspectives, suggests that prenatal exposure to widely used pesticides called organophosphates may increase your child's likelihood of developing attention disorders (such as ADHD) by time he or she is five years old.

How the Study Was Conducted

For this study, researchers from the University of California at Berkeley followed over 300 mothers and children who live in the Salinas Valley area – a region in California that is dominated by agriculture and pesticide use. When the mothers were still pregnant, the UC-Berkeley researchers tested the women's urine samples twice during pregnancy for its level of organophosphate metabolites (the breakdown products from the pesticides). Researchers believe that the metabolite levels in the urine were a good marker for the woman's exposure to pesticides.

The children of the pregnant women were followed up when they were 3.5 and 5 years old to see if they displayed any symptoms of ADHD. The children showed few symptoms at age 3, but by age 5, the evidence was clear.

What did the Results Show?

The results of the UC-Berkeley study showed the 5-year-olds, whose mothers were more exposed to pesticides during pregnancy, were more likely to have attention and behavior problems. In fact, the heavier the pesticide exposure during pregnancy, the more likely that 5-year-old would display symptoms of ADHD. The results were more significant among the boys.

It's important to note that the children in this study had higher than average exposure to pesticides, due to the agricultural region where they lived.

Although this study does seem concerning, since pesticides are commonly used on the commercial produce we eat, the researchers warn that this does not prove that pesticides cause ADHD. It indicates that there may be a link between the two, but other factors may also play a role.

Past Studies That Have Linked ADHD and Pesticide Exposure

Most recently, research published in the May 2010 issue of the Journal of Pediatrics came to a similar conclusion as the August study – organophosphate pesticides may contribute to ADHD.

The May study suggested that children with more exposure to organophosphate pesticides are more likely to have ADHD than children with less exposure. For their study, researchers studied the urine of 1,139 children (from age 8 to 15) across the United States and looked at the levels of pesticide byproducts in the urine. They found that the children with higher than average levels were at twice the risk of being diagnosed with ADHD.

About Organophosphate Pesticides and Why this is Important

In the United States, there are about 900 different types of pesticides (insect killing chemicals) that are used. Around 40 of these 900 are organophosphates, which are chemicals that work to kill insects by disrupting their brains and nervous systems. Unfortunately, this means that they can also harm the brains and nervous systems of people. In addition to the recent findings linking organophosphates to ADHD, past studies have linked exposure to these pesticides to Parkinson's disease.

Organophosphate pesticides can be found in trace amounts on commercially grown fruits and vegetables. Though there is no 100 percent way that you can protect you and your children from exposure to pesticides, there are certain things that you can do to reduce the level of exposure.

How to Protect Your Family

Fruits and vegetables are an important part of a healthy diet. They contain many of the essential vitamins, minerals, and fiber that will protect you from disease and keep you strong and healthy. A diet that is rich in fruits and vegetables may protect you from chronic diseases, such as heart disease, cancer, and even strokes. As a result, you will not want to cut these foods from your diet.

However, you can minimize you and your family's exposure to pesticides by:

  • Avoiding pesticide residue. You can also peel the fruit before you eat it.

  • Buying organic, whenever possible. Organic fruits and vegetables tend to contain fewer pesticides than commercial grown foods. Foods with the highest level of pesticides are often strawberries, peaches, raspberries, and celery. You will want to buy these in the organic food section for the best protection.
  • Buy from local farmers or at a local farmer's market, if it is available. Local farmers often use fewer pesticides, even when the produce is not organic.

Overview of ADHD

Attention deficit hyperactivity disorder, or ADHD, is a common neurobehavioral disorder that affects children, and it can last through adulthood. Over 4 million children between age 5 and 17 have the disorder, and it's believed that between 3 and 7 percent of school-aged children have ADHD.

Children who have ADHD often have trouble concentration, controlling their impulses, and are overly active. Common symptoms include:

  • Difficulty paying attention or staying focused on a task

  • Easily distracted

  • Doesn't seem to listen when they're spoken to

  • Doesn't follow through on instructions, and often does not finish schoolwork, chores, and duties

  • Avoids or dislikes tasks that require sustained attention, such as school work

  • Often forgetful in daily activities

  • Fidgets with hands or feet, or squirms when in seat

  • Often "on the go" and has to be moving around

  • Interrupts others (butts in on conversations)

There are three types of ADHD: predominantly inattentive type, predominantly hyperactive-impulsive type, and the combined type.

Researchers don't know what exactly causes ADHD, but they do know that genetics play an important role. An estimated one in four children with this disorder has at least one relative with ADHD.

Other possible causes and risk factors of ADHD include:

  • Environmental exposure, such as lead.

  • Smoking and drinking during pregnancy.

  • Altered brain function and anatomy – brain scans have revealed that the brain structure and activity of people with ADHD is different than the average person.

  • Premature birth and low birth weight.

ADHD is often treated with a combination of behavior therapy and medication.

top

Pregnancy A to Z