Pregnant women living within a mile of fields where pesticides were applied faced almost double the risk of having a baby who developed autism — compared to women who lived more than a mile away, a new study finds.

U.C. Davis researchers tracked pesticide applications on farms in the Central Valley, near Sacramento, and the Bay Area and matched that data to the addresses of women who lived nearby when they were pregnant.

The fetus tends to be vulnerable to certain kinds of insults,” said Irva Hertz-Picciotto, an environmental epidemiologist at the MIND Institute at U.C. Davis and lead author of the study. “Pesticides may be one of those sets of chemicals that we need to be particularly careful about.

The study was published Monday in Environmental Health Perspectives.

Studies linking autism with pesticide use are new and not wholly accepted within scientific circles. Clare Thorp is a scientist with Crop Life America, a trade association for pesticide producers. She says this kind of geographic-based research is limited. Just because women lived near fields where pesticides were used doesn’t mean they were actually exposed to the compounds.

“People who are at these addresses, they’re not always going to be standing out in their garden. They’re going to be inside the house or they might be at work, or they could be in the grocery store,” Thorp said.

She says the study never verified if pesticides entered women’s bodies by testing their skin or blood.

HealthDay reports that the authors of the study agree that this research represents only a small piece of the autism puzzle:

“These neurodevelopment disabilities are not the function of a single factor,” said Hertz-Picciotto. “I would suspect that there’s a number of different factors at play that have to do with maternal health, maternal nutrition, as well as chemicals that are used around the home as well as other factors like air pollution. It’s going to be an accumulation of factors for any one woman,” she said.

But based on her study, she said pregnant women should be aware that some of the chemicals found in commercial pesticides, like pyrethroids, are also sold for use around the home.

Even worse, they’re sometimes labeled as “all natural” products, because they’re based on a chemical that comes from chrysanthemum flowers. But Hertz-Picciotto says there’s nothing natural about them.

“It’s a synthetic product that’s been designed to be more toxic than the natural product it’s imitating,” she said.

Hertz-Picciotto recommends that pregnant women with insect problems play it safe by looking for less toxic alternatives.


Study Finds Pesticide Exposure in Pregnancy Linked to Autism 24 June,2014April Dembosky

  • Peggy Zuckerman

    This article and the one from the Sacramento Bee fail to include data that certainly are vital to this study. In addition, the headlines tout a relationship with risk of autism, though the study clearly included other developmental delays. The percentage of either is not clarified, nor is the definition of autism. Severe autism is a very different diagnosis than Asperger’s, but both are lumped into this review of the study. As to autism, one must ask how it was diagnosed and by whom. There is a tendency to seek such diagnoses in the school setting for a child who has learning difficulties, whether or not that diagnosis might hold medically.

    As with so many studies, the lack of real data and the casual redefinition of the study seen in the headlines becomes an impediment to real understanding.


April Dembosky

April Dembosky is the health reporter for The California Report and KQED News. She covers health policy and public health, and has reported extensively on the economics of health care, the roll-out of the Affordable Care Act in California, mental health and end-of-life issues.

Her work is regularly rebroadcast on NPR and has been recognized with awards from the Society for Professional Journalists (for sports reporting), and the Association of Health Care Journalists (for a story about pediatric hospice). Her hour-long radio documentary about home funerals won the Best New Artist award from the Third Coast International Audio Festival in 2009.

April occasionally moonlights on the arts beat, covering music and dance. Her story about the first symphony orchestra at Burning Man won the award for Best Use of Sound from the Public Radio News Directors Inc.

Before joining KQED in 2013, April covered technology and Silicon Valley for The Financial Times, and freelanced for Marketplace and The New York Times. She is a graduate of the University of California at Berkeley Graduate School of Journalism and Smith College.

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