SALINAS VALLEY, Calif. – Locals call this place
the world's salad bowl. Dole, Naturipe and Fresh Express are here, where
much of the global fruit and vegetable trade emerges in neat green
fields just over the hills from the Pacific Coast.
The difficulties facing migrant workers who plant and pick the crops is
an old story. But in Salinas, a new story is emerging -- one with
serious implications for the rest of the country and with an ending that
has yet to be written.
It is here that University of California, Berkeley public health
professor Brenda Eskenazi and her colleagues have spent the past 12
years studying mothers and children who are exposed to pesticides used
in the fields.
The
Center for Health Assessment of Mothers and Children of Salinas
(CHAMACOS) is a joint project of UC Berkeley, the Natividad Medical
Center, Clinica de Salud Del Valle de Salinas and other community
organizations. Its goal is to assess exposure to pesticides and other
pollutants in pregnant women and young children to determine the effects
on their health, and to try to prevent contact with the chemicals.
After
forming partnerships with local health care providers, the researchers
were able to recruit 600 women, who submitted to a series of tests to
measure pesticide levels in their bodies. Investigators tracked the
women throughout their pregnancies, waiting at hospitals as babies were
born to collect the umbilical cord blood. As the children grew, Eskenazi
and her team also charted their growth, mental development and general
health.
This group is now 10 ½ years old, and Eskenazi's work has set off alarms
among public health officials. She and her colleagues have found that
at age 2, the children of mothers who had the highest levels of
organophosphate pesticide metabolites in their blood had the worst
mental development in the group. They also had the most cases of
pervasive developmental disorder.
At age 5, the children whose mothers were most exposed during pregnancy
had poorer attention spans compared to those born to a mother who had
lower levels of pesticide metabolites in their urine. Metabolites, as
referred to here, are compounds that are formed as a chemical breaks
down in the body. They are evidence that someone was exposed to a
chemical.
"We have very, very high reports by the mother of behaviors consistent
with pervasive developmental disorder," said Eskenazi at a recent
neurotoxicology conference. "These include signs like the child is
afraid to try new things, can't stand anything out of place, and avoid
looking others in the eye. This is considered to be autism spectrum
behavior."
Researchers are currently studying whether children whose mothers were
exposed to pesticides during the pregnancy are more likely to develop
learning disabilities, behavior problems, asthma, diabetes and obesity
than other children.
The levels of pesticide metabolites found in the pregnant women in
CHAMACOS are higher than women who don't live in agricultural settings.
But the Centers for Disease Control and Prevention has found evidence
that the pesticides contaminating kids around the country, regardless of
proximity to agriculture, is high enough to raise questions about the
impact those pesticides may have on their growing brains. These days,
children are exposed to pesticides used in their homes, pesticide
residue on foods and sprays that drifts into playgrounds and other
sites. Eskenazi's work is being considered by the EPA as the agency
decides what to do with dozens of pesticides and other chemicals
suspected of being developmental neurotoxicants, that is, chemicals that
can rewire the brain and nervous system while a fetus is growing and
continuing to affect the brain in early life.
On a sunny day last summer, Eskenazi and Associate Director Kim Harley
visited an old trailer, which serves as headquarters for the center,
squeezed between a hospital and a county jail.
The trailer is cozy, with low couches for the kids, teddy bears and
dolls, videos of movies and cartoons. On the wall is a map of Salinas,
with pins showing the neighborhoods where the participants live. The
group has visited many of the participants at home, collecting samples
of pesticides and using a GPS to determine how far they are from the
fields.
Off the main room are small offices where technicians take blood and
urine samples from the children and their mothers, and examiners
administer a battery of tests designed to assess their memory, attention
span, IQ and other cognitive and emotional indicators.
On this day, child examiner Helen Aguirre is working with a 9-year-old
boy. He is shy, but they coax him into allowing them to check his
height. Then he follows them into the room for the other tests. They
tell him a story about a fishing trip, and then ask him to repeat the
salient facts. They talk about something else for a while, then ask him
how much he remembers about the fishing tale. They allow breaks for
snacks and a bit of television. The whole thing takes between 2 ½ and 3 ½
hours.
This is considered an observational study, but the researchers refer the
parents to a doctor if they find any health problems, such as asthma,
which is increasingly prevalent in Salinas, or high blood pressure. Next
door is a hospital, where almost all of the kids were born, and just
across the street, rows of lettuce, celery and broccoli.
"We have a high amount of pesticides used near this building," said
Eskenazi. "There are fields close by. When the wind is right, the
pesticides blow in."
The project has been so successful that the federal government has
funded the researchers to add a few more chemicals to the testing.
Their work also served as a model for the recently launched National
Children's Study, run by the National Institutes of Health, which seeks
to examine the effects of the environment on 100,000 children, tracking
them from before birth until age 21.
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