U.S. and European health officials need to take a fresh look at
assumptions about the safety and health impacts of glyphosate herbicides,
according to a group of health scientists worried about the chemicals’
explosive worldwide growth.
A scientific
review released February 16 warns that use of glyphosate has
skyrocketed, growing 15-fold in the 20 years since "Roundup Ready"
genetically engineered crops were introduced.
Government health agencies, they
said, have failed to adequately monitor how much of the herbicide is getting
into food and people and what impacts it might be having on our health.
Use of glyphosate in herbicides has increased exponentially
since it was first used in the 1970s, according to the review. The study,
published in the journal Environmental Health, was authored by 14 health
scientists mostly from universities. Pete Myers, founder and chief scientist at
Environmental Health Sciences, publisher of EHN.org, was the lead author of the
report.
Glyphosate, known most famously as Roundup but also sold under a
variety of brand names, is the most heavily used farm chemical in the history
of the world. Across the globe roughly 9.4 million tons of the chemical have
been sprayed on fields since 1974. Nearly 75 percent of that use has come in
the last 10 years, according to a separate report
Benbrook issued earlier this month.
That growth, said scientists reviewing the data, means
government benchmarks and safety levels are out of step with the reality of
exposure risk—for both the public and the environment.
Federal health agencies—such as the U.S. National Toxicology
Program, the U.S. Centers for Disease Control and Prevention and the German
Federal Institute for Risk Assessment—simply haven’t kept up, according to the
report.
“Since the late 1980s, only a few studies relevant to
identifying and quantifying human health risks have been submitted to the U.S.
EPA,” the authors wrote, adding that such assessments need to be based in
“up-to-date science.”
Glyphosate—a key ingredient in many weed-killer herbicides—works
largely by inhibiting a plant enzyme that doesn’t exist in mammals, so it was
initially thought the chemical posed little risk to humans and other
vertebrates.
However, evidence has been mounting that exposure to glyphosate
may not be so innocuous. The U.S. Department of Agriculture in 2011 found
glyphosate in 90 percent of 300 soybean samples, and the UK Food Standard
Agency found it in 27 out of 109 bread samples in 2012.
It’s been linked to liver and kidney
problems, birth defects, and it potentially disrupts the proper
functioning of hormones. In recent years, scientists have increasingly
suspected it might be at least partially behind a widespread
kidney disease epidemic in Sri Lanka and parts of India and
Central America.
Last year the World Health Organization’s International Agency
for Research on Cancer in March changed glyphosate’s status from a “possible”
to “probable” human carcinogen.
One of the main gaps identified in the report is the lack of
endocrine disruption testing, said Frederick vom Saal, University of Missouri
biologist and co author of the report. There is increasing evidence that
glyphosate may impact human hormones, which can spur numerous later health
impacts.
Standard federal testing is mostly done by dosing lab animals
with high amounts of a chemical, and then looking for obvious impacts such as
changes to organ weights and other malformations, said vom Saal. “Very little
is done in the way of looking at developmental issues.”
The studies done in the 1970s when glyphosate was approved were
“very unsophisticated,” Benbrook said. “The problem with dose ranges that are
very high is [that] research on developmental problems and endocrine disruption
has shown repeatedly chemicals can have subtle effects at much lower levels,”
he said.
The U.S. Environmental Protection Agency (EPA) concluded in
a report last June that
there was “no convincing evidence” that glyphosate is an endocrine disruptor.
EPA spokesman Robert Daguillard said the agency will review the
new report and added that they are finishing up preliminary human health and
ecological risk assessments, which are expected to be published for public
comment in 2016.
The health concerns coincide with more and more use and
pervasive exposure. Over the past decade glyphosate has been bundled up in the
debate over genetically modified food, because many seeds from companies such
as Monsanto—manufacturer of the most popular glyphosate herbicide, Roundup—are
genetically engineered to withstand the herbicide.
When crops such as corn and soybeans have such immunity, farmers
can spray entire fields. This has spurred a vicious cycle where weeds are
increasingly evolving resistance to the herbicides, leading to more and more
spraying.
“The geographic scope and severity of the weed control
challenges posed, worldwide, by the emergence and spread of
glyphosate-resistant weeds is unprecedented,” the authors wrote.
Glyphosate herbicides have proved controversial and have been
under the gun lately. Last week 35 House Democrats wrote a letter to
the EPA urging the agency to reassess the risks of Dow Chemical Co.’s glyphosate
herbicide Enlist Duo given the WHO’s cancer findings.
“EPA registered Enlist Duo without considering this cancer
finding, and without looking at any studies on glyphosate’s cancer risk that
have been published in the last twenty years,” wrote the lawmakers, led by
Reps. Earl Blumenauer and Peter DeFazio.
Dow Chemical Co. did not respond to a request for comment on the
new review. Monsanto spokesperson Charla Marie Lord said in an emailed response
that the report's concerns were not in line with what regulatory agencies have
found.
"No regulatory agency in the world considers glyphosate to
be a carcinogen," she said. "Regulatory agencies have not had any
health concerns that would necessitate testing of the sort proposed by the
authors of this essay."
The company in January filed a lawsuit against California’s
Office of Environmental Health Hazard Assessment designed to prevent glyphosate
from being added to the state’s list of known carcinogens.
It’s not clear what kind of impact a statement from a group of
scientists can have on federal policy. But vom Saal said that even if the EPA
does not alter testing, it could spur more progressive states such as
California to take action.
Benbrook said a modern test, conducted by independent
scientists, is long overdue.
“I hope they don’t show anything and we can move on,” Benbrook
said. “But if there’s even a small chance of health impacts, when you’re
talking about everyone on the planet, that should cause us to use some
caution.”
For questions or feedback about this piece, contact Brian
Bienkowski at bbienkowski@ehn.org.