JUDY WOODRUFF: It's not well known to the general public yet that the Environmental
Protection Agency under President Trump wants to change which scientific studies can be
used by the federal government to regulate industry.
The administration and business voices say studies should be used only if all of the
data is publicly available and transparent.
But many scientists and researchers say doing so would violate privacy protections for patients
in studies.
This issue is now playing out in a long-running battle over whether the ban pesticides that
harm babies and children.
Miles O'Brien looks at the science and the debate behind it all.
It's part of our weekly series on the Leading Edge of science, medicine and technology.
MILES O'BRIEN: When Fidelia Morales moved into her dream home nestled among the orange
groves in California's Central Valley 12 years ago, she didn't know much about agriculture.
FIDELIA MORALES, California (through translator): We didn't we know that they were communicating
with these huge machines, that they were spraying these extremely strong chemicals.
MILES O'BRIEN: It happens on the calm margins of the day.
When the when lays down, growers gear up to spray their crops with pesticides.
FIDELIA MORALES (through translator): Look at the distance between the machine and our
yard.
It's impossible to keep the pesticides off my property.
Sometimes, at night, we have the air conditioning on and we can still smell the pesticides they're
praying throughout the entire house.
MILES O'BRIEN: She wonders what the chemicals may be doing to her children, especially her
youngest son, the only one born here.
FIDELIA MORALES (through translator): He can't sit in one place.
We have received many complaints about him from his teachers, who say he needs to focus.
MILES O'BRIEN: While it is hard to make a direct link, those are textbooks symptoms
of exposure to chemicals known as organophosphates.
The most widely used variety is chlorpyrifos, manufactured by DowDuPont.
After decades of research reviews and debate, the Environmental Protection Agency was on
the cusp of banning all use of chlorpyrifos in November of 2016.
But in March of 2017, then EPA administrator Scott Pruitt delayed a decision on the ban
by five years, saying American farms that rely on the insecticide needed regulatory
certainty.
DowDuPont called it the right decision for farmers.
And yet, on August 9, a panel of federal judges ruled the EPA had no justification to allow
continued use of chlorpyrifos in the face of scientific evidence that its residue on
food causes neurodevelopmental damage to children.
Chlorpyrifos and other organophosphates are neurotoxins, a poison that attacks the nervous
system.
ROBERT SAPOLSKY, Stanford University: It causes a huge excitatory burst in the nervous system.
MILES O'BRIEN: Robert Sapolsky is a professor of neuroscience at Stanford University.
The burst of nerve firing can be so severe, it works the neurons to death.
The body's response?
The nervous system tries to repair itself by growing new connections to patch the damaged
circuit.
ROBERT SAPOLSKY: And one of the things that sometimes happens is, the wiring goes sort
of haywire, and a neuron will wind up coming back and stimulating itself, so that every
time it fires, it stimulates itself, and it fires and fires.
And what you have now set up, with a positive feedback loop like this, is chronic seizure
disorder.
MILES O'BRIEN: First introduced as an insecticide in 1965, chlorpyrifos was sold to consumers
for home and garden use under various brand names, including Raid.
ACTOR: Hello.
ACTOR: Goodbye.
NARRATOR: It really kills them dead.
MILES O'BRIEN: It was widely used, even though scientists had published evidence that exposure
to organophosphates causes permanent brain damage in rodents.
So what were the consequences for humans exposed to this neurotoxin?
VIRGINIA RAUH, Columbia University Mailman School of Public Health: We knew we had a
chemical that was worthy of taking a look at if we were concerned about its potential
adverse effects.
MILES O'BRIEN: Virginia Rauh is an epidemiologist at the Columbia University Mailman School
of Public Health.
For 20 years now, she has followed 750 mothers and their children in the Washington Heights
section of Manhattan.
Pregnant mothers in her study wore a backpack with a pump designed to gather air samples
as they went about their daily routine.
Rauh's team found organophosphates in 99 percent of the air samples they gathered and 70 percent
of the blood samples of the children.
Rauh's conclusion, higher levels of organophosphates found in the blood of her subjects lead to
lower birth weight, reduced I.Q., ADHD symptoms and tremors.
MRIs of the brains of exposed subjects reveal enlargement in some areas and abnormally thin
cortices, the outermost layer of nerve cells in the brain, crucial for cognitive functions
such as perception, language, memory, and consciousness.
VIRGINIA RAUH: I think, in reality, there is no safe level.
It depends upon the level of risk that we tolerate as a society.
But to damage even to the extent of several I.Q. points or some very tiny attentional
issues, in my mind, is not acceptable, if we know that it is associated with an exposure.
MILES O'BRIEN: The Food Quality Protection Act says exposure to a pesticide must be safe
for infants and children if it is going to be used on food.
With evidence mounting that chlorpyrifos posed a human health hazard, the chemical industry
struck a deal with the EPA in 2002 to stop selling the pesticide for home use.
Raid and other consumer products were reformulated, and some agricultural uses were curtailed.
But, today, chlorpyrifos remains a favorite among farmers.
When we met, Bob Blakely was vice president at California Citrus Mutual, which represents
growers.
BOB BLAKELY, Former Vice President, California Citrus Mutual: And the studies that are being
referenced to buy a lot of those who are -- who are opposed to this -- this chemical have
not been replicated and they have been not been substantiated by the rest of the scientific
community, nor they have been duplicated in other countries.
MILES O'BRIEN: The EPA says the Columbia data remains inaccessible and has hindered the
agency's ongoing process to fully evaluate the pesticide.
Dow says it remains confident that authorized uses of chlorpyrifos products as directed
offer wide margins of protection for human health and safety.
The company has funded several studies that support that conclusion.
Robert Sapolsky and a team of neuroscientists at Stanford pored through many of these papers.
ROBERT SAPOLSKY: Freshman science majors are not supposed to make mistakes like these.
The science was basically empty.
MILES O'BRIEN: And he says every time there was a mistake -- and there were dozens of
them -- it favored the industry position that organophosphates, used properly, don't harm
humans.
ROBERT SAPOLSKY: For literature as a whole as lousy as the subset of these papers that
I looked at, this really does bring into question lots of things, most basically, whether Dow
has a leg to stand on saying this stuff has been scientifically shown to be safe.
MILES O'BRIEN: EPA scientists agree.
But in the Trump administration, their conclusions are frequently overruled by industry pressure.
Miriam Rotkin-Ellman senior scientist with the Natural Resources Defense Council, which
is suing the EPA, hoping to force the agency to follow its own rules and take its own scientific
advice.
MIRIAM ROTKIN-ELLMAN, Natural Resources Defense Council: when we have the evidence right in
front of us that an exposure that's widespread in the American population could be or is
increasing the risk of those learning disabilities, and we are refusing to take action on that,
it's terrifying.
MILES O'BRIEN: Especially so for Fidelia Morales and her family, surrounded by citrus and pesticides
in California.
FIDELIA MORALES (through translator): If our children are exposed to chlorpyrifos, they
are not going to have a future.
Together, as a community, we're fighting for them to stop and to prohibit the use of chlorpyrifos
here in this county.
I think that they don't care, because, if they did care, they would try to stop this
without us asking.
MILES O'BRIEN: The state of Hawaii recently banned chlorpyrifos.
And California's EPA has come to the same scientific conclusions as their federal counterparts.
That could lead to a statewide ban there.
Meanwhile, the federal court has ordered the EPA to enact a ban on chlorpyrifos nationwide
within 60 days.
The agency can appeal, but says it is still reviewing the decision.
In California's Central Valley, I'm Miles O'Brien for the "PBS NewsHour."