Reflections on Reporting About Pesticides and Neuroscience

Published on
November 11, 2013

When I visited the Salinas Valley in Central California this past summer for a story about the effects of pesticides on neurodevelopment, stark scenes were not hard to find. On a short trip to see the agricultural fields up close, we drove past a shoddy, poorly maintained apartment complex located less than 50 feet from a wealthy landowner’s grape vineyard. At this so-called ‘labor camp,’ home to low-income Mexican-American farmworkers who work the surrounding fields, toys were strewn in the yards and children’s bikes leaned against broken, rusty chain-link fences. A young girl rode idly by on a pink princess bike, glancing at us curiously. A boy, approximately 8 years old, clung to the leg of his father and grinned upward at us as we drove past, displaying a mouthful of missing teeth and gold fillings.

This agricultural valley, known as the “Salad Bowl of the World,” produces about half of the nation’s spinach and three-quarters of the nation’s lettuce, along with an abundance of strawberries, broccoli, tomatoes, and other produce destined for supermarkets across the country. It’s a region of bounty, with agricultural sales averaging $4 billion annually. Against the backdrop of lush green, well-manicured rows of produce, the poverty of the farmworkers who labor in the fields is blunt and unsettling.

Throughout my reporting for this story, which ran as part of a package on pesticides in Science magazine in August, I found that I continually needed to be aware of my own biases. Given these images and the topic at hand, it is difficult not to view the farmworkers and their families as victims and those who manufacture pesticides (not to mention those of us who benefit from them) as the perpetrators. Yet repeatedly, I was reminded of the complexity of the issues involved, and I walked away with the uneasy sense that there was no clear-cut solution.

My story focused on what researchers are learning about the potential effects of one main class of pesticides — organophosphates — on brain development during the prenatal period and early childhood. Understanding the effects of environmental chemical exposure during the prenatal period is of critical importance because research is revealing the great extent to which human health and subsequent disease risk are programmed in the womb.

I highlighted the work of two research groups that have been running community-based cohort studies since the late 1990s. One team, based at the University of California, Berkeley, studies pesticide exposure in agricultural settings in the Salinas Valley. The other, based at Columbia University in New York, examines the effects of indoor pesticide exposure in New York City.

The Columbia group has looked closely at the effects of exposure to a once-ubiquitous residential pesticide called chlorpyrifos (one of the most widely used organophosphate pesticides), which was phased out for most indoor use in the United States in 2001. The Columbia researchers have reported that children exposed in the womb to high levels of chlorpyrifos have lower IQs than children in the low-exposure group along with cognitive delays, ADHD symptoms, and other attention and behavioral problems in the first few years of life.

In the first human brain imaging study to examine how particular brain regions might be affected by chemical exposure, the researchers reported that certain brain regions that are critical for cognition and behavior were enlarged in children in the high-exposure group and that these children had abnormal development in brain regions involved in gender differentiation. The research team is finding that the developmental differences they observed in early childhood are following these kids, now 12-14 years of age, into adolescence.

The Berkeley team has not focused solely on chlorpyrifos but rather on the whole suite of organophosphate pesticides to which farmworkers and their families are exposed. Their long-term study has turned up strikingly similar links between organophosphate exposure and impaired childhood development as the Columbia group.

As a mother of three, as a journalist, and as a human being, I feel a sense of indignation at these findings — especially when viewed from a historical perspective. The following quote, written by Rachel Carson in Silent Spring in 1962, provides some perspective: “No longer are exposures to dangerous chemicals occupational alone; they have entered the environment of everyone—even of children as yet unborn.” Fifty years later, we have seen sweeping overhauls of environmental regulations. And yet, in light of what these researchers are learning, it seems clear that change hasn’t come quickly enough.

During my reporting, I posed these thoughts to Lynn Goldman, dean of the George Washington University School of Public Health and Health Services in Washington, D.C. Goldman is a pediatrician and an epidemiologist, and she was an assistant administrator for the Environmental Protection Agency in the 1990s. In that role, she was in charge of the office that regulates chemicals and pesticides. I asked her how it is possible that we can have such laissez-faire regulations on pesticides, akin to an ‘innocent until proven guilty’ stance towards these chemicals.

Goldman explained to me that — in her perspective — while that sentiment might be true of chemical regulations overall in the U.S., it is not true of pesticides. Because pesticides are applied to food crops, they fall under the jurisdiction of the U.S. Food and Drug Administration and receive far higher scrutiny than most other environmental chemicals, says Goldman. In 1996, Congress enacted the Food Quality Protection Act, which called for more stringent safety standards, particularly for infants and children. The act required EPA to reevaluate the ‘tolerance,’ or allowable levels of a given pesticide on an individual food and to take into account the aggregate amount of pesticide exposure from other sources. In other words, not only did the EPA have to consider the risk of exposure from consuming pesticides like chlorpyrifos on produce, but it also had to evaluate total exposure from crack and crevice spraying, carpet spraying, termite control on soil foundations around homes, and even flea-dipping for pets. This helped drive the phase-out of chlorpyrifos for most indoor use, says Goldman.

Still, this explanation begs the question: How is exposure evaluated in agricultural settings, such as for the families who live next door to the vineyard? Or the families who live downwind of the fields where spraying occurs? How much data is enough to drive a change in policy for use of organophosphates? And what do we know about the safety of the pesticides that would replace them?

Eric Lauritzen, agricultural commissioner for Monterey County in California, grapples with the complexities behind the issue daily. Lauritzen’s job is to enforce the existing regulations and to handle potential acute pesticide exposures or environmental contaminations. Lauritzen says that he values the Berkeley center’s research and its findings but is “left struggling with what to do” in response.

“We don’t have enough information in any sort of stretch to say we just shouldn’t use these [pesticides] anymore,” says Lauritzen. “The [Berkeley] studies are very important from a scientific research standpoint, but from a public policy standpoint they do not provide some other essential information needed to make public policy decisions.” For instance, he says, the studies don’t provide answers to questions such as: What are the main routes of exposure for these farmworkers and their families? Are the pesticides coming in on workers clothes? Are they moving in the air, or is high exposure due to home use of pesticides or consumption of fresh fruits and vegetables with residues on them? What are the pathways?

In addition to the regulatory complexities I encountered, I also grappled with conflicted feelings over the implications of the studies for the farmworkers. Half of the families in Monterey County, where the Salinas Valley is located, are “food insecure,” meaning that they have limited access to nutritious meals or don’t always know where their next meal will come from. In fact, Monterey County has more adults living in “food insecure” households than any other county in the state. This poverty is concentrated in the so-called “east side” of Salinas, made up primarily of farmworkers and their families. It’s impossible to miss the irony that their labor is putting food on the tables of more affluent Americans like myself.

So when I met and interviewed three of the families who are participants in Berkeley’s cohort study, known as the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), I found myself unsure how to broach the question of how the participants feel about the results of the studies. Did they see themselves as victims? Do they feel wronged? How concerned are they about the findings?

In my small sample size of three families, they did not express that they felt like victims. Rather, they were grateful to be participants in the study and grateful that the questions were being examined. Through the community support provided by the study, they are learning about practical measures, such as changing their clothes as soon as they get home from the fields. One mother, Guillermina Aguilar, who enrolled in the study when she was pregnant with her now 13-year-old son, Eric, expressed that pesticides are simply a fact of life. “It’s something that we don’t have a choice about,” says Aguilar. “They need to [use pesticides] to keep the vegetables in good shape. How can we give our opinions? They need to do what they need to do.”

And this brought me back to the question at hand. How do we, as a society, respond to the science? And how long do we wait to find out what the science is going to tell us?

Image by Greencolander via Flickr