In what could be a clue to the mysterious rise of attention deficit and hyperactivity disorder (ADHD) in kids, researchers have linked even low levels of a common pesticide to the disruptive behavioral disease. The study, published in the Journal of Pediatrics, looks at the organophosphate pesticide malathion, commonly used on fruits and vegetables. (Watch an ABC report about the ADHD study.) Here, a brief guide to the findings:

How big a problem is ADHD?
An estimated 3 percent to 7 percent of U.S. children are believed to have ADHD, with boys much more likely to be affected. The rate has mushroomed over the past 30 to 40 years, but it's unclear whether the actual incidence ADHD has increased or whether the condition was underdiagnosed in the past.

What did the study find?
The researchers looked at urine samples from 1,139 kids age 8 to 15. The 119 who were diagnosed with ADHD also tended to have the highest concentrations of malathion in their urine. And it didn't take much of the pesticide to raise ADHD risk considerably.

Is it conclusive?
No, but it is pretty suggestive. Previous studies of specific high-risk groups — like the children of farmworkers — have shown that substantial exposure to pesticides can affect brain development. The new research is evidence that the broader public could also be at risk. Epidemiologist Brenda Eskenazi of the University of California-Berkeley says the new study is "interesting and provocative … because the levels of pesticide are very low." Pesticide manufacturers caution that more study is needed to prove a causal link from malathion to ADHD. 

What can I do, as a consumer, if I'm concerned?
Buy organic fruits and vegetables whenever possible, especially with pesticide-heavy produce like strawberries, raspberries, and peaches. Also, get rid of bug spray and other pesticides in your house, and pesticides you might use to maintain your lawn and garden.

What if organic produce is unavailable, or just too expensive?
The Environmental Working Group says that, based on government data, these fruits and vegetables are relatively safe, even if not certified organic: Onions, avocados, fresh local corn ears, pineapples, mangoes, asparagus, sweet peas, kiwis, cabbage, eggplant, papaya, watermelon, broccoli, sweet potatoes, and, surprisingly, tomatoes. Always wash produce under running water before eating it.

Sources: ABC News, LA Times, MomLogic, The Daily Green