New weed killer studies raise concern for reproductive health

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As Bayer AG seeks to discount concerns that Monsanto’s glyphosate-based herbicides cause cancer, several new studies are raising questions about the chemical’s potential impact on reproductive health.

An assortment of animal studies released this summer indicate that glyphosate exposures impact reproductive organs and could threaten fertility, adding fresh evidence that the weed killing agent might be an endocrine disruptor. Endocrine disrupting chemicals may mimic or interfere with the body’s hormones and are linked with developmental and reproductive problems as well as brain and immune system dysfunction.

In a paper published last month in Molecular and Cellular Endocrinology, four researchers from Argentina said that studies contradict assurances by the U.S. Environmental Protection Agency (EPA) that glyphosate is safe.

The new research comes as Bayer is attempting to settle more than 100,000 claims brought in the United States by people who allege exposure to Monsanto’s Roundup and other glyphosate-based herbicide products caused them to develop non-Hodgkin lymphoma. The plaintiffs in the nationwide litigation also claim Monsanto has long sought to hide the risks of its herbicides.

Bayer inherited the Roundup litigation when it bought Monsanto in 2018, shortly before the first of three trial victories for plaintiffs.

The studies also come as consumer groups work to better understand how to reduce their exposure to glyphosate through diet. A study published Aug. 11 found that after switching to an organic diet for just a few days, people could cut the levels of glyphosate found in their urine by more than 70 percent. Notably, the researchers found that the children in the study had much higher levels of glyphosate in their urine than did the adults. Both adults and children saw large drops in the presence of the pesticide following the diet change.

Glyphosate, the active ingredient in Roundup, is the most widely used weed killer in the world. Monsanto introduced glyphosate-tolerant crops in the 1990s to encourage farmers to spray glyphosate directly over whole fields of crops, killing weeds but not the genetically altered crops. The widespread use of glyphosate, by farmers as well as homeowners, utilities and public entities, has drawn growing concern over the years because of its pervasiveness and fears about what it could be doing to human and environmental health. The chemical is now found commonly in food and water and in human urine.

According to the Argentinian scientists, some of the reported effects of glyphosate seen in the new animal studies are due to exposure to high doses; but there is new evidence showing that even low dose exposure could also alter the development of the female reproductive tract, with consequences on fertility. When animals are exposed to glyphosate before puberty, alterations are seen in the development and differentiation of ovarian follicles and the uterus, the scientists said. Additionally, exposure to herbicides made with glyphosate during gestation could alter the development of the offspring. It all adds up to show that glyphosate and glyphosate-based herbicides are endocrine disruptors, the researchers concluded.

Agricultural scientist Don Huber, professor emeritus from Purdue University, said the new research expands on knowledge about the potential scope of damage associated with glyphosate and glyphosate-based herbicides and provides a “better grasp of understanding the seriousness of the exposure that is ubiquitous in our culture now.”

Huber has warned for years that Monsanto’s Roundup might be contributing to fertility problems in livestock.

One noteworthy study published online in July in the journal Food and Chemical Toxicology,  determined that glyphosate or glyphosate-based herbicides disrupted “critical hormonal and uterine molecular targets” in exposed pregnant rats.

A different study recently published in the journal Toxicology and Applied Pharmacology by researchers from Iowa State University looked at glyphosate exposure in mice. The researchers concluded that chronic low-level exposure to glyphosate “alters the ovarian proteome” (a set of expressed proteins in a given type of cell or organism) and “may ultimately impact ovarian function. In a related paper from the same two Iowa State researchers and one additional author, published in Reproductive Toxicology, the researchers said they did not find endocrine disrupting effects in the mice exposed to glyphosate, however.  

Researchers from the University of Georgia reported in the journal Veterinary and Animal Science that consumption by livestock of grain laced with glyphosate residues appeared to carry potential harm for the animals, according to a review of studies on the topic. Based on the literature review, glyphosate-based herbicides appear to act as “reproductive toxicants, having a wide range of effects on both the male and female reproductive systems,” the researchers said.

Alarming results were also seen in sheep. A study published in the journal Environmental Pollution looked at the impacts of glyphosate exposure on the development of the uterus in female lambs. They found changes that they said might affect the female reproductive health of sheep and show glyphosate-based herbicides acting as an endocrine disruptor.

Also published in Environmental Pollution, scientists from Finland and Spain said in a new paper that they had performed the first long-term experiment of the effects of “sub-toxic” glyphosate exposure on poultry. They experimentally exposed female and male quails to glyphosate-based herbicides from the ages of 10 days to 52 weeks.

The researchers concluded that the glyphosate herbicides could “modulate key physiological pathways, antioxidant status, testosterone, and the microbiome” but they did not detect effects on reproduction. They said the effects of glyphosate may not always be visible with “traditional, especially short-term, toxicology testing, and such testing may not fully capture the risks…”

Glyphosate and Neonicotinoids

One of the newest studies looking at glyphosate impacts on health was published this month in the International Journal of Environmental Research and Public Health.  Researchers concluded that glyphosate as well as the insecticides thiacloprid and imidacloprid, were potential endocrine disruptors.

The insecticides are part of the neonicotinoid class of chemicals and are among the most heavily used insecticides in the world.

The researchers said that they monitored the effect of glyphosate and the two neonicotinoids on two critical targets of the endocrine system: Aromatase, the enzyme responsible for estrogen biosynthesis, and estrogen receptor alpha, the main protein promoting estrogen signaling.

Their results were mixed. The researchers said with respect to glyphosate, the weed killer inhibited aromatase activity but the inhibition was “partial and weak.” Importantly the researchers said glyphosate did not induce estrogenic activity. The results were “consistent” with the screening program conducted by U.S. Environmental Protection Agency, which concluded that “there is no convincing evidence of a potential interaction with the estrogen pathway for glyphosate,” they said.

The researchers did see estrogenic activity with imidacloprid and thiacloprid, but at concentrations higher than the pesticide levels measured in human biological samples. The researchers concluded that “low doses of these pesticides should not be considered harmless,” however, because these pesticides, together with other endocrine disrupting chemicals, “might cause an overall estrogenic effect.”

The varying findings come as many countries and localities around the world evaluate whether or not to limit or ban continued use of glyphosate herbicides.

A California appeals court ruled last month that there was “abundant” evidence that glyphosate, together with the other ingredients in Roundup products, caused cancer.

U.S. regulators relied for years on flawed pesticide data provided by Dow Chemical

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For years, U.S. regulators relied on falsified data provided by Dow Chemical to allow unsafe levels of the chemical chlorpyrifos into American homes, according to a new analysis from University of Washington researchers.

The analysis reexamines work from the 1970s sponsored by Dow and submitted to the Environmental Protection Agency (EPA) to guide the agency in establishing what scientists refer to as a “no-observed-adverse-effect-level” or NOAEL. Such thresholds are used to determine what types of use and at what level a chemical exposure can be allowed and still be considered “safe.”

According to the new analysis, published online July 3 in the journal Environmental International, the inaccurate findings were the result of a chlorpyrifos dosing study conducted by researcher Frederick Coulston and colleagues from the Albany Medical College in the early 1970s for Dow.

The authors of the new paper reexamining that prior work are Lianne Sheppard, Seth McGrew and Richard Fenske of the Department of Environmental and Occupational Health Sciences, School of Public Health at the University of Washington.

While the study was authored by the Coulston group, the analysis was completed by a Dow statistician and concluded that 0.03 mg/kg-day was the chronic NOAEL level for chlorpyrifos in humans. But the new analysis by the University of Washington researchers found that wildly overstated the margin of safety. Had the data been properly analyzed a lower NOAEL of 0.014 mg/kg-day would have been found, they said.

The Coulston study did not undergo peer review but still was used by the EPA for risk assessments throughout much of the 1980′s and 1990′s, the University of Washington researchers reported.

The researchers concluded: “During that period, EPA allowed chlorpyrifos to be registered for multiple residential uses that were later cancelled to reduce potential health impacts to children and infants. Had appropriate analyses been employed in the evaluation of this study, it is likely that many of those registered uses of chlorpyrifos would not have been authorized by EPA. This work demonstrates that reliance by pesticide regulators on research results that have not been properly peer-reviewed may needlessly endanger the public.”

Widely used

Commonly known as the active ingredient in the brand name Lorsban, chlorpyrifos insecticides were introduced by Dow Chemical in 1965 and have been used widely in agricultural settings. The largest agricultural market for chlorpyrifos is corn but the pesticide is also used by farmers growing soybeans, fruit and nut trees, Brussels sprouts, cranberries, and cauliflower, as well as other row crops. Residues of the chemical are commonly found in food. Non-agricultural uses include golf courses, turf, green houses, and utilities.

Despite the science promoted by Dow, independent scientific research has shown mounting evidence of the dangers of chlorpyrifos, particularly to young children. Scientists have found that prenatal exposures to chlorpyrifos are associated with lower birth weight, reduced IQ, the loss of working memory, attention disorders, and delayed motor development.

The American Academy for Pediatrics, which represents more than 66,000 pediatricians and pediatric surgeons, has warned that continued use of the chemical puts developing fetuses, infants, children and pregnant women at great risk.

Chlorpyrifos is so dangerous that the European Food Safety Authority has stated that there is no safe exposure level.

The EPA reached an agreement with Dow in 2000 to phase out all residential uses of the chemical because of research showing the chemical is dangerous to the developing brains of babies and young children. In 2012, chlorpyrifos was banned from use around schools.

In February 2020, after pressure from consumer, medical, scientific groups and in face of growing calls for bans around the world, Corteva AgriScience, a successor corporation to a merger of Dow and DuPont, said it would phase out production of chlorpyrifos. The chemical, however, remains legal for other companies to make and sell.

Human subjects

The study that is the subject of the new paper by the University of Washington researchers was overseen in 1971 by the Albany Medical College’s Institute of Experimental Pathology and Toxicology. The study included 16 healthy adult male inmates from a pool of volunteers at Clinton Correctional Facility, a maximum-security prison in Dannemora, New York.

The volunteers were randomized into four experimental groups, including one control group, whose members received a daily placebo. The members of the three other groups received daily chlorpyrifos treatments at three different doses.  The study took place over 63 days.

The new analysis found several problems with the study, including the omission of eight valid baseline measurements for one of the three treatment groups.

“Such an omission of valid data without justification is a form of data falsification that violates all standard codes of ethical research practice and is classified as outright research misconduct,” the University of Washington researchers concluded.

The researchers said that chlorpyrifos “passed through the regulatory process without much debate,” even though there was “growing evidence that it might pose a health hazard in residential environments.”

“The Coulston Study misled regulators by omitting valid data,” and “may have adversely impacted public health” for several years, the University of Washington paper concludes.

U.S. regulators relied for years on flawed pesticide data provided by Dow Chemical

Print Email Share Tweet

For years, U.S. regulators relied on falsified data provided by Dow Chemical to allow unsafe levels of the chemical chlorpyrifos into American homes, according to a new analysis from University of Washington researchers.

The analysis reexamines work from the 1970s sponsored by Dow and submitted to the Environmental Protection Agency (EPA) to guide the agency in establishing what scientists refer to as a “no-observed-adverse-effect-level” or NOAEL. Such thresholds are used to determine what types of use and at what level a chemical exposure can be allowed and still be considered “safe.”

According to the new analysis, published online July 3 in the journal Environmental International, the inaccurate findings were the result of a chlorpyrifos dosing study conducted by researcher Frederick Coulston and colleagues from the Albany Medical College in the early 1970s for Dow.

The authors of the new paper reexamining that prior work are Lianne Sheppard, Seth McGrew and Richard Fenske of the Department of Environmental and Occupational Health Sciences, School of Public Health at the University of Washington.

While the study was authored by the Coulston group, the analysis was completed by a Dow statistician and concluded that 0.03 mg/kg-day was the chronic NOAEL level for chlorpyrifos in humans. But the new analysis by the University of Washington researchers found that wildly overstated the margin of safety. Had the data been properly analyzed a lower NOAEL of 0.014 mg/kg-day would have been found, they said.

The Coulston study did not undergo peer review but still was used by the EPA for risk assessments throughout much of the 1980′s and 1990′s, the University of Washington researchers reported.

The researchers concluded: “During that period, EPA allowed chlorpyrifos to be registered for multiple residential uses that were later cancelled to reduce potential health impacts to children and infants. Had appropriate analyses been employed in the evaluation of this study, it is likely that many of those registered uses of chlorpyrifos would not have been authorized by EPA. This work demonstrates that reliance by pesticide regulators on research results that have not been properly peer-reviewed may needlessly endanger the public.”

Widely used

Commonly known as the active ingredient in the brand name Lorsban, chlorpyrifos insecticides were introduced by Dow Chemical in 1965 and have been used widely in agricultural settings. The largest agricultural market for chlorpyrifos is corn but the pesticide is also used by farmers growing soybeans, fruit and nut trees, Brussels sprouts, cranberries, and cauliflower, as well as other row crops. Residues of the chemical are commonly found in food. Non-agricultural uses include golf courses, turf, green houses, and utilities.

Despite the science promoted by Dow, independent scientific research has shown mounting evidence of the dangers of chlorpyrifos, particularly to young children. Scientists have found that prenatal exposures to chlorpyrifos are associated with lower birth weight, reduced IQ, the loss of working memory, attention disorders, and delayed motor development.

The American Academy for Pediatrics, which represents more than 66,000 pediatricians and pediatric surgeons, has warned that continued use of the chemical puts developing fetuses, infants, children and pregnant women at great risk.

Chlorpyrifos is so dangerous that the European Food Safety Authority has stated that there is no safe exposure level.

The EPA reached an agreement with Dow in 2000 to phase out all residential uses of the chemical because of research showing the chemical is dangerous to the developing brains of babies and young children. In 2012, chlorpyrifos was banned from use around schools.

In February 2020, after pressure from consumer, medical, scientific groups and in face of growing calls for bans around the world, Corteva AgriScience, a successor corporation to a merger of Dow and DuPont, said it would phase out production of chlorpyrifos. The chemical, however, remains legal for other companies to make and sell.

Human subjects

The study that is the subject of the new paper by the University of Washington researchers was overseen in 1971 by the Albany Medical College’s Institute of Experimental Pathology and Toxicology. The study included 16 healthy adult male inmates from a pool of volunteers at Clinton Correctional Facility, a maximum-security prison in Dannemora, New York.

The volunteers were randomized into four experimental groups, including one control group, whose members received a daily placebo. The members of the three other groups received daily chlorpyrifos treatments at three different doses.  The study took place over 63 days.

The new analysis found several problems with the study, including the omission of eight valid baseline measurements for one of the three treatment groups.

“Such an omission of valid data without justification is a form of data falsification that violates all standard codes of ethical research practice and is classified as outright research misconduct,” the University of Washington researchers concluded.

The researchers said that chlorpyrifos “passed through the regulatory process without much debate,” even though there was “growing evidence that it might pose a health hazard in residential environments.”

“The Coulston Study misled regulators by omitting valid data,” and “may have adversely impacted public health” for several years, the University of Washington paper concludes.

An Unappetizing Analysis from the FDA

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Last month the Food & Drug Administration published its latest annual analysis of the levels of pesticide residues that contaminate the fruits and veggies and other foods we Americans routinely put on our dinner plates. The fresh data adds to growing consumer concern and scientific debate over how pesticide residues in food may contribute – or not – to illness, disease and reproductive problems.

Over 55 pages of data, charts and graphs, the FDA’s “Pesticide Residue Monitoring Program” report also provides a rather unappetizing example of the degree to which U.S. farmers have come to rely on synthetic insecticides, fungicides and herbicides in growing our food.

We learn, for instance, in reading the latest report, that traces of pesticides were found in 84 percent of domestic samples of fruits, and 53 percent of vegetables, as well as 42 percent of grains and 73 percent of food samples simply listed as “other.” The samples were drawn from around the country, including from California, Texas, Kansas, New York and Wisconsin.

Roughly 94 percent of grapes, grape juice and raisins tested positive for pesticide residues as did 99 percent of strawberries, 88 percent of apples and apple juice, and 33 percent of rice products, according to the FDA data.

Imported fruits and vegetables actually showed a lower prevalence of pesticides, with 52 percent of fruits and 46 percent of vegetables from abroad testing positive for pesticides. Those samples came from more than 40 countries, including Mexico, China, India and Canada.

We also learn that for the most recently reported sampling, among the hundreds of different pesticides, the FDA found traces of the long-banned insecticide DDT in food samples, as well as chlorpyrifos, 2,4-D and glyphosate.  DDT is linked to breast cancer, infertility and miscarriage, while chlorpyrifos – another insecticide – has been scientifically shown to cause neurodevelopmental problems in young children.

Chlorpyrifos is so dangerous that the European Food Safety Authority has recommended a ban of the chemical in Europe, finding that there is no safe exposure level. The herbicides 2,4-D and glyphosate are both linked to cancers and other health problems as well.

Thailand recently said it was banning glyphosate and chlorpyrifos due to the scientifically established risks of these pesticides.

Despite the prevalence of pesticides found in U.S. foods, the FDA, along with the Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA), assert that pesticide residues in food are really nothing to worry about. Amid heavy lobbying by the agrichemical industry the EPA has actually supported continued use of glyphosate and chlorpyrifos in food production.

The regulators echo the words of Monsanto executives and others in the chemical industry by insisting that pesticide residues pose no threat to human health as long as the levels of each type of residue falls under a “tolerance” level set by the EPA.

In the most recent FDA analysis, only 3.8 percent of domestic foods had residue levels that were considered illegally high, or “violative.” For imported foods, 10.4 percent of the foods sampled were violative, according to the FDA.

What the FDA did not say, and what regulatory agencies routinely avoid saying publicly, is that the tolerance levels for certain pesticides have risen over the years as the companies that sell the pesticides request higher and higher legal limits. The EPA has approved several increases allowed for glyphosate residues in food, for instance. As well, the agency often makes the determination that it need not comply with a legal requirement that states the EPA  “shall apply an additional tenfold margin of safety for infants and children” in setting the legal levels for pesticide residues. The  EPA has overridden that requirement in the setting of many pesticide tolerances, saying no such extra margin of safety is needed to protect children.

The bottom line: The higher the EPA sets the “tolerance” allowed as the legal limit, the lower the possibility that regulators will have to report “violative” residues in our food.  As a result, the U.S. routinely allows higher levels of pesticide residues in food than other developed nations. For example, the legal limit for the weed killer glyphosate on an apple is 0.2 parts per million (ppm) in the United States but only half that level – 0.1 ppm – is allowed on an apple in the European Union. As well, the U.S. allows residues of glyphosate on corn at 5 ppm, while the EU allows only 1 ppm.

As legal limits rise for pesticide residues in food, many scientists have been increasingly raising alarms about the risks of regular consumption of the residues, and the lack of regulatory consideration of the potential cumulative impacts of consuming an array of bug and weed killers with every meal.

A team of Harvard scientists are calling for in-depth research about potential links between disease and consumption of pesticide as they estimate that more  than 90 percent of people in the United States have  pesticide residues in their urine and blood due to consumption of pesticide-laced foods.  A study connected to Harvard found that dietary pesticide exposure within a “typical” range was associated both with problems women had getting pregnant and delivering live babies.

Additional studies have found other health problems tied to dietary exposures to pesticides, including to glyphosate.  Glyphosate is the most widely used herbicide in the world and is the active ingredient in Monsanto’s branded Roundup and other weed killing products.

Pesticide Industry Push Back 

But as the concerns mount, agrichemical industry allies are pushing back. This month a group of three researchers with long-standing close ties to the companies that sell agricultural pesticides released a report seeking to soothe consumer worries and discount the scientific research.

The report, which was issued Oct. 21, stated that “there is no direct scientific or medical evidence indicating that typical exposure of consumers to pesticide residues poses any health risk. Pesticide residue data and exposure estimates typically demonstrate that food consumers are exposed to levels of pesticide residues that are several orders of magnitude below those of potential health concern.”

Not surprisingly, the three authors of the report are closely tied to the agrichemical industry. One of the report’s authors is Steve Savage, an agrichemical industry consultant and former DuPont employee. Another is Carol Burns, a former scientist for Dow Chemical and current consultant for Cortevia Agriscience, a spin-off of  DowDuPont. The third author is Carl Winter, Chair of the Department of Food Science and Technology at the University of California at Davis. The university has received approximately $2 million a year from the agrichemical industry, according to a university researcher, though the accuracy of that figure has not been established.

The authors took their report directly to Congress, holding three different presentations in Washington, D.C., designed to promote their message of pesticide safety for use in “media food safety stories, and consumer advice regarding which foods consumers should (or should not) consume.”

The pro-pesticide sessions were held at the office buildings for members of Congress and, appropriately it seems, at the headquarters for CropLife America, the lobbyist for the agrichemical industry.