San Francisco Chronicle
Pesticides' effect on generations of field-workers
Long-term study looks at how widespread chemicals affect generations of field-workers in Salinas Lea Suzuki, The Chronicle
A portion of this article is being re publisehd with permission of the author
September 23, 2013
Health problems prevalent
Good health is precarious for many of Monterey County's 422,000 residents. One-third of adults are uninsured; a quarter of children are in poverty. From 2002 to 2012, the percentage of special-education students with learning disabilities fell, but those with autism, intellectual disabilities and speech impairments increased, according to county data. Researchers wanted to understand the health problems that might be getting overlooked.
Then there were the pesticides. About 9 million to 10 million pounds were used annually throughout the county during the late 1990s. The amount has dropped slightly, though the county still ranks sixth in the state for pesticide use.
Eskenazi submitted a proposal to the National Institutes of Health to study low-income pregnant women and environmental effects on their children, and won the funding.
Now she just had to find moms.
Gonzalez moved to Salinas from Michoacán, Mexico, two decades ago, landing a job in the fields. She was among thousands of farmworkers in Monterey County who rise before dawn to gather an estimated three-fourths of the nation's salad greens.
In late 1999, Gonzalez became pregnant with her fourth child, a boy. During a checkup at Natividad Medical Center in Salinas, a volunteer with Eskenazi's study talked her into enrolling.
So began a series of annual or biannual visits to the researchers' trailer outside the hospital. During her pregnancy and delivery, Gonzalez gave them samples of blood, urine, cord blood and breast milk, let them inspect her house and answered dozens of questions about her lifestyle. She was among 601 pregnant women in the initial stages of the study.
Gonzalez's son, Richard Luna, was born in July 2000, one of more than 500 infants in the Chamacos project born between 2000 and 2002.
From the time they were 6 months old, and every one to two years after, researchers analyzed their urine, blood, saliva, teeth and hair. The kids had physical exams and took tests that assessed their motor skills and intelligence.
Much of what the scientists later reported was troubling. They found, for instance, that mothers in the study have higher traces of pesticides in their systems compared with the general U.S. population. Children with high prenatal exposure to pesticides show greater signs of developmental delays than those with low prenatal exposure.
There are limits to what researchers can learn. They can know Richard's blood pressure, IQ scores or pesticide levels. But they don't have enough information to link those factors to his poor eyesight or asthma, or tell his mother whether her time in the fields played a role in those issues. None of their research attributes a health problem to a single direct cause, and they stress that not every potentially harmful factor is equally dangerous in everyone.
"People aren't exposed to one thing," Eskenazi said. "They're exposed to everything around them, including air pollution and alcohol and smoking."
First focus: pesticides
Still, researchers have a lot of educated guesses.
They began their study by examining organophosphate pesticides, a commonly used type known to harm the human nervous system.
One of the researchers' first findings, in 2005, showed the chemicals' presence in the urine of the women in their study group in greater quantity than women of child-bearing age in the general U.S population.
Scientists also noticed that the higher the mother's pesticide levels prior to delivery, the higher the chance their baby would demonstrate abnormal reflexes, such as passive leg movements, after the first three days of life.
The finding preceded many others. At age 5, youths who had been exposed to high levels of pesticides in the womb were more likely than others to score high on tests that determine the likelihood of attention deficit hyperactivity disorder, or ADHD.
When the children were 7, researchers noted a 5.5-point drop in overall IQ scores for every 10-fold increase in the mothers' pesticides level during pregnancy.
The findings may resonate beyond the valley and across the nation, other researchers say.
"They're helping us understand the links between early exposures and health outcomes that are significant not only in terms of children's functioning and well-being in their early years, but also ... over the entire life course," said Frederica Perera, director of the Columbia Center for Children's Environmental Health in New York, which has collaborated with UC Berkeley.
Other scientists have reached similar conclusions about the same exposures. In a 2011 study of New York City children, for example, Mount Sinai School of Medicine found that those with prenatal exposure to pesticides were likely to lag in mental development in their early years.
More than just a study
More studies will follow. Right now, the UC Berkeley team is examining baby teeth for traces of banned fungicides that contain manganese, a chemical element toxic in high doses.
Eskenazi's intent is not to scare residents, but to give them meaningful knowledge. "In my heart, this is more than just a study for me," she said. "This is a population I deeply care about."
The professor plans to keep up the studies as long as there is funding - and Gonzalez and her son plan to keep showing up. Maybe, the mother says, they can help their neighbors understand what is all around them.
"We are all breathing it in," she said.
This article was produced for The California Endowment Health Journalism Fellowships (ReportingonHealth.org), a program of USC Annenberg's School of Journalism. Stephanie M. Lee is a San Francisco Chronicle staff writer. E-mail: [email protected] Twitter: @stephaniemlee