Industry bias taints study on widely used insecticide
Researchers who examined Dow
Chemical Company-sponsored animal tests performed two decades ago on the
insecticide chlorpyrifos found inaccuracies in what the company reported to the
U.S. Environmental Protection Agency compared to what the data showed.
And, according to internal EPA
communication, agency scientists also had issues with the study
interpretations, yet the agency approved the compound for continued use anyway.
"EPA staff scientists and staff
were telling management there were problems," said Jennifer Sass, senior
scientist with the Natural Resources Defense Council, who was not involved in
the current study but has worked on issues related to toxics, including
chlorpyrifos, for decades.
"And management disregarded
it."
Those 20-year-old industry studies are still used by regulatory agencies such as the EPA and the European Food Safety Authority in approving continued use of the controversial insecticide, which is used on beans, citrus, corn, cotton, wheat and soybeans.
"Exaggerated trust in the
reporting" by regulators led to a "failure" of both U.S. and EU
authorities to act on red flags, the authors wrote.
The results, published in
the journal Environmental Health, are timely: The EPA is appealing a court decision that
would mandate a ban on chlorpyrifos residue on food (which would effectively
mean a ban on farm-use); and the European Union is considering a ban as well.
The Obama Administration's EPA in
2015 proposed a ban of the chemical on food (that would have likely taken
effect in early 2017), but President Trump's former EPA Administrator Scott
Pruitt reversed the decision.
In August, however, a three-judge
panel on the Ninth Circuit Court of Appeals ordered the EPA to ban the
chemical. The EPA has appealed the decision.
Multiple studies since the industry-funded
research have shown toxic impacts, especially to children, from chlorpyrifos
exposure.
Those studies have linked fetal exposure to lower IQ's and reduced gray matter in the brain later in life. Health researchers have increasingly sounded the alarm that the chemical should be banned due to its potential for impacts on young nervous systems.
Those studies have linked fetal exposure to lower IQ's and reduced gray matter in the brain later in life. Health researchers have increasingly sounded the alarm that the chemical should be banned due to its potential for impacts on young nervous systems.
The chemical was developed as a
nerve gas during World War II.
There's no surprise it's toxic
"because it was designed from chemical warfare agents," Sass said.
The new study is a peek behind the
curtain at the stark discrepancy between industry and independent science on
the chemical.
"If all of this raw data had
been scrutinized properly, it should have at least required further testing to
see if these findings were abnormal," Philippe Grandjean, senior author on
the study and a researcher and adjunct professor of environmental health at
Harvard T.H. Chan School of Public Health, told EHN.
"In our minds, their [Dow] data are not appropriate to prove that [chlorpyrifos] is not a neurotoxicant."
"In our minds, their [Dow] data are not appropriate to prove that [chlorpyrifos] is not a neurotoxicant."
Inaccuracies in the reporting
The researchers, led by Axel Mie, an
assistant professor in the department of clinical science and education at the
Karolinska Institute, requested the data for two industry lab animal
studies—one from 1998, and one in 2015.
One study tested chlorpyrifos
exposure on rats, while the other was a rat study of chlorpyrifos-methyl, a
breakdown chemical from chlorpyrifos.
Key findings:
The lab, Argus Research Laboratories
in Pennsylvania, used a 2 percent cut off for what constitutes
"statistically significant" findings throughout most of the study,
instead of the scientific standard of 5 percent. This is important because it
is a stricter interpretation of data and would make it more likely that they
wouldn't find impacts from exposure.
When the lab looked at dimensions of
the brain after exposure, they didn't look at individuals but put them all
together and took an average.
"When we looked at least one dimension in the rats, cerebellum height was decreased and linked to exposure to chlorpyrifos in newborn pups," Grandjean said.
"In the other test study where they examined chlorpyrifos-methyl those data were in part missing, so we were unable to see if the same thing happened with the sister compound. And there was no explanation for the data being unavailable."
"When we looked at least one dimension in the rats, cerebellum height was decreased and linked to exposure to chlorpyrifos in newborn pups," Grandjean said.
"In the other test study where they examined chlorpyrifos-methyl those data were in part missing, so we were unable to see if the same thing happened with the sister compound. And there was no explanation for the data being unavailable."
The rat studies failed to model
human exposure and potential brain impacts. "The brain growth spurt occurs
mainly postnatally in rats but prenatally in humans," Mie and colleague
wrote.
However, the newborn pups in the industry studies had decreased levels of exposure once born because only a fraction of chlorpyrifos is transferred via milk.
However, the newborn pups in the industry studies had decreased levels of exposure once born because only a fraction of chlorpyrifos is transferred via milk.
The test facility for the studies
was "unable to detect neurobehavioral effects of elevated developmental
exposure to lead nitrate, although lead is a confirmed developmental
neurotoxicant at very low doses," the authors wrote.
"We believe there were some
inaccuracies in the reporting and in the summary provided by Dow to the EPA and
EFSA," Grandjean said. "And this goes back something like 20 years,
when all of this testing was being done, and this is what current approval of
chlorpyrifos relies on."
"Federal agencies need to stop
doing negotiations with registrants"
Grandjean said there were several
hundred pages of data.
In communication between EPA
toxicologists and those responsible for registering pesticides, it's clear
agency scientists were well aware of study interpretation problems.
"The study was graded
unacceptable due to an inadequate presentation of the statistical data
analysis," wrote Susan Makris, formerly with the toxicology branch of the
EPA, in a 2000 note to
the agency's reregistration branch.
An EPA spokesperson said the agency
is reviewing the new study.
"What happened in the end was
EPA management overriding their own science and technical experts," Sass
said.
Sass added that EPA scientists are
now on the "right track" — looking at low dose exposures and specific
impacts to developing children.
And now it's up to management and
administration officials to follow the science.
"This [study] just shows that
industry can't be trusted on how it reports data, and federal agencies need to
stop doing negotiations with registrants," Sass said.
EHN has reached out to Dow Chemical
Company and will update the story when they respond.