Is glyphosate carcinogenic?

Is glyphosate carcinogenic?

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

I'm trying to understand if glyphosate is carcinogenic. The information in internet is very confusing. There are many ecological oriented websites which claim it's carcinogenic which I suppose they could be biased, but also news websites stating that World Health Organization says "it's probably carcinogenic". In the other hand the European Union seems to sustain it's not, and it extended its license of use in a "heated debate". is it known if glyphosate is carcinogenic or not, or just there isn't enough evidence to sustain one thing or the other?

There is a difference between potential and risk. That's why different agencies came to different conclusions.

The IARC (International Agency for Research on Cancer, a body of the WHO) assesses the potential of a compound to cause cancer. They go through the research that point into this direction and if there is any hint that any dose of the compound might cause cancer they have to rate it accordingly. If you go through the IARC report on glyphosate, you find that a lot of the studies they looked into did not actually find a link between glyphosate and cancer in humans. Nevertheless, there are some studies that show that high doses of glyphosate can result in cancer in animals. So, the IARC had to conclude that glyphosate has the potential to cause cancer. They put it into the category 2A (probable carcinogens). In the same category you find red meat, hot beverages and being a hairdresser, because these things have the potential of causing cancer.

Agencies like the FDA, EFSA etc. are assessing the risk of cancer from "normal" glyphosate exposure. While it seems to be possible to get cancer from "too much" glyphosate, we are only exposed to a tiny fraction of that dose. While it's unavoidable that small amounts of glyphosate residues are found in our food, these amounts are most probably not harmful. At least, that's what most research concludes. The dose makes the poison. While eating fresh organic berries does not pose any risk to harm you, they naturally contain small quantities of chemicals that have the potential to harm you at high concentrations. Your body itself makes small amounts of compounds that have the potential to harm you (e.g. Formaldehyde).

That's why the debate is so heated. Environmental activists are taking the cancer potential assessment of the IARC and turn it into a risk for the consumer, which is untrue. If they would work with the same energy against other group 2A carcinogens, we would have to close down barber shops…

So, does glyphosate has the potential to cause cancer? Probably yes. Does this provide a risk for the consumer/farmer? Probably no.

The research on Glyphosate and cancer is ambiguous however the journal Nature published a paper on January 9, 2017 that found that rats fed ultra-low doses of glyphosate developed non-alcoholic fatty liver disease. The article is: Multiomics reveal non-alcoholic fatty liver disease in rats following chronic exposure to an ultra-low dose of Roundup herbicide

EPA says glyphosate not carcinogenic, poses environmental risks (Update)

The EPA says herbicide glyphosate could pose risks to pollinators such as monarch butterflies, but is not carcinogenic

The US Environmental Protection Agency (EPA) said Tuesday that the weed killer glyphosate is unlikely to cause cancer in humans, but recommended new measures to prevent potential ecological risks, especially to monarch butterflies and other pollinators.

Glyphosate developer Monsanto was convicted in 2018 and 2019 of not taking necessary steps to warn of the potential risks of Roundup—their weed killer containing the chemical, which two California juries found caused cancer in two users.

But in a statement, EPA Administrator Andrew Wheeler said the agency found "no risks to public health from the current registered uses of glyphosate."

It did propose new instructions, subject to a public comment period, for farmers and others using the chemical to reduce "spray drift" that can harm butterflies.

Under those regulations, glyphosate labels in the US would have to instruct aerial users to not spray the chemical from more than 10 feet (three meters) above crops, or if wind speeds exceed 15 miles per hour (24 kilometers per hour).

Meanwhile, labels would also be required to state that when applied from the ground, the chemical must not be sprayed from more than four feet above crops—and that all nozzles must be set to mist the product at a "fine" or coarser setting.

The proposed instructions also include new regulations around glyphosate's use around water.

The EPA said the chemical presents a "low toxicity" to honey bees, but does present a "potential risk" to birds and plants, including aquatic plants.

The agency will publish its final revised regulations at the end of the year.

Agriculture secretary Sonny Perdue praised the proposed regulations, and said glyphosate is an important part of US agriculture.

"USDA applauds EPA's proposed registration decision as it is science-based and consistent with the findings of other regulatory authorities that glyphosate does not pose a carcinogenic hazard to humans," he said in a statement.

The EPA's findings contradict those of the International Agency for Research on Cancer, part of the World Health Organization, which said in 2015 that glyphosate was likely carcinogenic.

German pharmaceutical firm Bayer, which bought Monsanto last year, announced last week that over 13,000 lawsuits related to the weed killer have been launched in the US.

Why Dr. Zach Bush believes herbicides could end life on Earth

By Nicole Karlis
Published October 14, 2019 6:00PM (EDT)

Agricultural worker spraying his crops (Getty Images)


This article was co-produced with Original Thinkers, an annual ideas festival in Telluride, Colorado that brings speakers, art and filmmakers together to create new paradigms.

Dr. Zach Bush will tell you he is “very much” trained as a traditional, patient-facing MD, yet you wouldn’t necessarily expect that given his present-day work. After studying internal medicine, which included a training on hormone medicine, Bush became interested in cancer research and started developing chemotherapy treatments. Yet he soon felt frustrated that his work was doing nothing to prevent the things that caused cancer in the first place.

“I went from that world of chemotherapy and drug concepts and drug development to the sudden realization that there had never been a cancer caused by a lack of chemotherapy,” Bush told me. “And so, no matter how good I got at making chemotherapy, I was always going to be missing the point, missing the root cause of the situation.”

This realization redirected his focus to nutrition. Eventually he opened a nutrition center in rural Virginia. “And out of that experience, we realized that the nutrition of today on the grocery store shelves was not really working as it had in the 1960s,” he said. “And that took us down into this new era of chemical farming and the discoveries of the chemicals that were in the soils.”

That took Bush on a path towards studying glyphosate, the herbicide introduced by Monsanto in 1974 for agricultural weed control, and which is the primary ingredient in common consumer pesticides like RoundUp. In the late 1990s, Monsanto began creating genetically modified crops that were resistant to glyphosate, called "RoundUp Ready" seeds — meaning farmers could spray glyphosate heavily on their crops and expect that only the weeds, and not their crops, would be affected. The US Department of Agriculture notes that 90 percent of domestic corn crops are genetically modified seeds that are resistant to glyphosate or other herbicides.

The World Health Organization's International Agency for Research on Cancer (IARC) declared glyphosate as a "probable carcinogen" in 2015. That would be fine and good if it was something that we rarely came into contact with, but, a s a result of its ubiquity in crops like corn and soy, glyphosate has infiltrated much of our food system, and creeps into our diets unbidden. As Salon's Matt Rozsa reported earlier this year, an Environmental Working Group study tested 21 oat-based cereal and snack products for glyphosate. 17 of then contained glyphosate at levels considered unsafe for children, including multiple brands of Cheerios.

I spoke to Dr. Bush at the Original Thinkers festival in Telluride, Colorado this interview has been condensed and edited for print.

Nicole Karlis: Can you share more about how you came to believe that glyphosate could be at the root of so many different health issues?

Dr. Zach Bush: Yeah, it was totally by accident on my side. So, I was studying soil, found some carbon molecules made by bacteria and fungi in soil, and therefore, in our gut, as well, that had medicinal qualities similar to the chemotherapy [drugs] I used to make. And that was the sudden "Aha!" moment that closed the question of, "How come, when we're missing some bacteria, we get cancer?"

And so, we had found these correlations, but we hadn't figured out causation. And when we found these molecules, I felt like I was starting to put the dots together between changes in the microbiome and cancer — we were suddenly missing this family of molecules that were capable of giving this "medicine" from the soil.

We started studying these carbon molecules in human cell cultures and [doing] experiments in cancer cells. And one of my chief scientists [had] the realization that this was causing cell repair to happen at a very rapid rate in gut cells, and the repair that it was doing was actually repairing the same injury that was caused by glyphosate, which is the active ingredient in Roundup.

And so, in a roundabout way, we found the solution to it before I found the problem. I didn't know about the glyphosate issue, really. As I started researching glyphosate and Roundup in the context of the human health collapse, suddenly I found all of these correlations in the medical literature and soil literature, public health statistics, to show that this Roundup chemical was added to our food chain in 1996. And every year, more [is put] into the global environment . [it] has really undermined, not just human biology, but biology in our water systems, soil systems, oceans, and now [is] destroying the ecosystem at large.

Some people might say "Well, I haven't used Roundup, so maybe I'm untouched by it." Is that true?

Unfortunately, it's a water-soluble molecule. As it evaporates, we start breathing it in our air, which has a high-water content, and then it ends up in our clouds, and it rains down. [W]e're at about almost four and a half billion pounds of glyphosate used in soils worldwide every year.

What do you know that this chemical does to the human body?

The first thing it does is act as an antibiotic in the soil and in our gut, and so this molecule is taken up into our food. So, it's not something you can wash off. It's actually in the flesh of the tomato, corn, soybean, whatever it hits. And so, it's integrated in that water structure, and as it hits your gut microbiome [it] acts as an antibiotic to kill the microbial diversity in your intestines. We now know [this] is the beginning of chronic disease, many chronic diseases are now being mapped back to injuries in the microbiome. And so, as we wipe out the bacteria and fungi with this broad spectrum antibiotic in our food, we are killing the health of our animals, the livestock we consume, beef, poultry, pork, and everything else. So, we're making those animals sick.

As humans, we're seeing the same pattern. This epidemic of chronic disease has emerged from this collapse of the microbiome. The glyphosate antibiotic holds our whole gut and vascular lining together. Those are called tight junctions, and the tight junction Velcros are responsible for creating intelligent barriers. Your gut membrane is the largest barrier to the outside world: it covers two tennis courts in surface area and is the thickness of half of the width of a human hair. So, it's this tiny microscopic cellophane-like covering that separates the outside world from your human biology. What glyphosate and Roundup does is perforate that membrane by destroying those tight junctions and creating something — that's now been called "leaky gut" in the public — in the medical literature it's called gut permeability — it increases gut permeability.

And so, that injury starts to activate the immune system, and we become reactive to our foods. So, we develop allergies of all sorts, pollen allergies and environmental allergies, but also all the food allergies that have become so prevalent in our children today. And so, we lose the barrier system, and so at that point, not only have you become chronically inflamed, you're also literally losing self-identity.

How do we get rid of this chemical in our food system?

Step one: stop spraying it, so it dissipates in the environment over time. The way it does dissipate is through microbial digestion, so fortunately, there are microbes on the earth that can digest any toxin we can think of — because ultimately, the toxins we develop are just rearrangements of molecules that are already existed on Earth. If we stopped spraying today, over the next 50 years, we could see the toxicity levels drop to levels that we could probably tolerate better. We started a nonprofit called Farmer's Footprint that's working and training chemical farmers to learn how to farm without these chemicals. Our nonprofit is working to regenerate 5 million acres under this model over the next six years.

So, what gives you hope with all of this?

The rate of repair is hopeful, so my hope is really steeped in the speed at which biology responds to just a little break. So, if we can just stop the injury for a moment, Mother Earth and biology itself has such a resilient nature. Life itself is resilient, and will repair.

It is possible that we're beyond the recovery of the human species where we've got maybe 60 or 70 years left as a species at our current trajectory of collapse.

Because of chemicals like glyphosate?

More than that, because of everything we're doing. I'd say Roundup is our public enemy number one probably, but that's one of 260 chemicals that are now prevalent in our food system. So, we have completely chemicalized the human experience and the planet itself, and so the level of toxicity has superseded the planet's capacity for life. We've lost [biodiversity] on the planet in the last 40 or 50 years, and so we're almost halfway done with this great extinction. And we're not paying attention to it very well.

If farmers stop using Roundup, how will that impact food costs?

[Not using Roundup can] save tons of money. It turns out, when we go into regenerative agriculture, the farmers make five times to 10 times their bottom line income in three to five years. And so, they can get themselves out of the bankruptcy that they're all facing right now by just stopping all the inputs — the amount of money that the banks are forcing them to borrow against our chemical fertilizers, chemical herbicides, chemical pesticides, and that bankrupts 6,000, 8,000 farms a year. And so, if we just stop those inputs and we go back to nature's natural cycles, we get healthy soil within three to five years, and the productivity of that farm explodes because not only is the crop yield starting to improve, [they're] also getting diversification of their income streams. And we've completely eliminated 90% of their costs. The income potential for these farmers is radical, and so because of that — because of those economic markers — I have real hope.

Glyphosate’s Mechanism of Action

The “gly” in glyphosate actually stands for the amino acid glycine. The glycine amino acid in glyphosate has a methylphosphonate group attached to its nitrogen atom, which is responsible for its effects and toxicity.

After studying the research literature on glyphosate, Seneff has reached the conclusion that your body sometimes substitutes glyphosate for the amino acid glycine when it is constructing proteins, and this can have devastating consequences in some cases. The proteins created with glyphosate instead of glycine simply don’t work because glyphosate is much larger than glycine and also negatively charged, and as a result this alters important physical characteristics.

Monsanto’s own research, dating back to the late 1980s, shows that glyphosate accumulates in various tissues, even though they claim it doesn’t. 1 The Monsanto researchers proposed that it was “incorporated into” the proteins in the tissues. This is not widely appreciated, even in the natural health community.

Now, if you have a distorted analog of glycine (in the form of glyphosate), the protein constructed from it is not going to work like it’s supposed to. In her book, Seneff details the amino acids in proteins that are most susceptible to damage because of what she calls a “glyphosate susceptible motif.”

“It’s really fascinating biology and so terrifying when you think of the potential consequences, if I’m right,” she says. “It matches so well with all the diseases that are going up dramatically in our society that I really think I’m onto something huge here.”

An aromatic amino acid called EPSP synthase is a critical enzyme that almost surely gets disrupted by glyphosate through this mechanism of substituting for glycine. This gets a bit technical, but it is important. The plant version of EPSP synthase binds a phosphate group in its substrate phosphoenolpyruvate at a site where there is a highly-conserved glycine residue (highly conserved usually means that it is critical for proper function).

It has been shown experimentally that, if you change the DNA code so that the glycine is substituted by an amino acid called alanine (one extra methyl group), the enzyme becomes completely insensitive to glyphosate at any concentration. It also takes a hit on phosphate binding because of the extra methyl group, but you can tweak another amino acid nearby to fix this problem, while still keeping its insensitivity to glyphosate.

EPA Concludes Glyphosate Is Not Likely to Be Carcinogenic to Humans

In December 2017, the US Environmental Protection Agency (EPA) released the draft human health risk assessment for glyphosate, the active ingredient in Roundup. The human health assessment concluded that “glyphosate is not likely to be carcinogenic to humans” and found “no other meaningful risks to human health” when used in accordance with label instructions.

Findings from the human health assessment align with nearly every major regulatory body in the world including Canada, Europe, Germany and the United Nations however, the EPA conclusion contradicts the World Health Organization’s International Agency for Research on Cancer (IARC), who classified glyphosate as a “Class 2A probable carcinogen to humans” in 2015. The IARC decision generated considerable attention and fueled concerns over human health risks associated with glyphosate use around the globe. Unlike other regulatory agencies, IARC disclosed little about its review process, making it difficult to determine how IARC arrived at its decision. Yet, as part of litigation proceedings, many IARC ‘draft’ documents surfaced and when compared with the published reports, several critical edits were identified by Reuters and preliminary ecological risk assessment released in 2015 raised concerns, one of which was the uncertainty surrounding toxicity data for a class of surfactants (polyethoxylated tallow amines) used in select glyphosate formulations (e.g. Roundup). While it may seem inconsequential, the vast majority of toxicity studies used technical material (glyphosate alone) and not a commercial formulation. This creates a dilemma for the EPA as the bulk of toxicity data for glyphosate may not fully characterize the hazard end products (commercial formulations) may present.

In the digital age, the ability to search for and disseminate information has allowed society to connect on a scale once inconceivable. While few can argue the benefits the internet provides, it undoubtedly played a role in the negative public perception around pesticides and the IARC classification of glyphosate as a probable carcinogen is no exception. Today, an individual may encounter anti-pesticide articles based on faulty science and/or personal agendas disguised as a legitimate source that may lead them to form a negative sentiment towards the topic. Scientists can dispute false claims and publish peer-reviewed research, but the reality is that less of those articles will gain traction compared to flashy headlines, like “Glyphosate is Killing Your Child”.

For years, glyphosate has generated contentious debate and although the EPA findings will not satisfy all sides, it illustrates the immense responsibility that falls on the agency. People are quick to criticize the agency, yet all the data they use to formulate their conclusions are grounded in science and publically accessible. Ultimately, the allegations leveled against IARC demonstrate the necessity for subjectivity and transparency in the regulatory decision-making process. Finally, EPA is scheduled to publish their proposed registration review decision for glyphosate in 2019 which will outline any proposed mitigation measures, if needed.

Monsanto 'Outraged'

The company says the IARC finding contradicts decades of evidence about the chemical.

“We are outraged with this assessment,” Robert Fraley, PhD, Monsanto chief technology officer, says in a statement. “This conclusion is inconsistent with the decades of ongoing comprehensive safety reviews by leading regulatory authors around the world.”

Ray McAllister, PhD, senior director of regulatory policy for CropLife America, an advocacy group for agro-chemical makers, says the IARC didn’t consider many studies the industry has produced to prove glyphosate’s safety.

“A consumer shouldn’t be worried about” the chemical, McAllister says.

Glyphosates Can Linger, Cause Plant Infertility

Glyphosate-based herbicides (GBH) are commonly applied to many outdoor environments and are widely used in agriculture and forestry. Scientists have now suggested that these herbicides can linger in plants and may have deleterious impacts on their health. The work, which was reported in Frontiers in Plant Sciences, showed that a year after GBH was applied, there were deformities in reproductive parts of a plant called prickly rose (Rosa acicularis).

In this study, the researchers gathered GBH-treated samples of prickly rose from both greenhouse-grown wild plants and 'cutblocks' from natural areas where these plants compete with conifers growing in commercial harvesting operations, as well as untreated prickly rose from different places.

The work showed that one year after the applications of GBH, the pollen viability of glyphosate-treated plants went down 66 percent on average compared to untreated controls. Over 30 percent of a part of the plant that contains pollen, called the anthers, did not open up, and these flowers became functionally infertile. There were also color changes that may disrupt their interactions with pollinating insects. There were still traces of GBH on these plants two years after the initial application.

"The changes to plants have been documented in the past, in agricultural plants, so it is not surprising to find them in forests," said Dr. Lisa J. Wood, an assistant professor in the Department of Ecosystem Science and Management at UNBC. "What is important is the timeline. To continue to find these effects one to two years after herbicide applications, in new parts of growing plants, is noteworthy."

Honeybees are attracted to prickly rose plants, so they may be impacted by GBH traces. Glyphosate has been in use since the 1970s but concern is growing about its safety, and the carcinogenic impacts it might have on humans.

The researchers are planning to continue this work they want to know whether GBH-induced color changes in the plants actually do reduce the interest pollinators have in them. They also want to determine whether insects and hummingbirds carry glyphosate residues.

"This will tell us if pollinators are taking up residues from the plants they feed on," Wood explained. "We will also research other plants to see if the changes we observed in the wild rose are also found in other flowers."

Research has suggested that glyphosate isn't acutely toxic to most organisms at levels that are typically used in Canada, but we still don't know much about what the long-term effects of glyphosate use may be, or how it alters the natural environment.

"The more we learn the better, and research can always be used to better inform management," Wood noted. "Herbicide practices may change if the research shows that this is in the public's best interest."

Courts and science – talc

Let’s start right with the conclusions from two of the most premiere cancer research organizations in the USA – the American Cancer Society (ACS) and the National Cancer Institute (NCI), both filled with scientists who have more cancer science expertise in their pinky fingers than the judges, juries, and attorneys involved in these cases.

The ACS states that research on talc and ovarian cancer “have been mixed, with some studies reporting a slightly increased risk and some reporting no increase … For any individual woman, if there is an increased risk, the overall increase is likely to be very small.”

The NCI concludes that “the weight of evidence does not support an association between perineal talc exposure and an increased risk of ovarian cancer.”

So, how did these claims become so prevalent and become the basis of these lawsuits? The blame goes to a case-control epidemiological study from the 1980s published in the journal Cancer. These case-control studies, considered middle-level quality in the hierarchy of biomedical research, asked women, one group with ovarian cancer and another group without it, to recall their past diet and activities, including talcum power use.

Case-control studies have serious drawbacks – they rely too much on memory, which can, and often is, clouded by recall bias. Participants may forget what they did, how often they did it, or other key data points. Moreover, those who have cancer tend to overestimate their use of a suspected causal substance. On the other hand, individuals who don’t have cancer may be less motivated to remember details. Case-control studies are just incapable of determining causal links between talcum powder and cancer.

On the other hand, more powerful studies, called cohort studies, showed no link. Unlike the case-control studies, which rely on memory, these cohort studies followed a large number of women and monitored their health over time. The women recorded their activities in real time. These type of studies rank higher in the hierarchy of biomedical research because the data is stronger.

One of the most powerful of these studies, which included more than 61,000 women tracked over 12 years, found no correlation between talc and ovarian cancer. The authors concluded that “based on our results, perineal powder use does not appear to influence ovarian cancer risk.”

Another robust cohort study, published in Epidemiology in 2016, followed nearly 51,000 women over seven years, and once again, found no link. The scientists concluded that talc use was not “associated with increased risk of ovarian cancer.”

However, a recent systematic review (which are considered the pinnacle of biomedical research) seems to indicate that there might be a link between talc and ovarian cancer. As I keep writing, just because a systematic review has been published doesn’t mean it should be subject to analysis and criticism. And what I noticed in the paper is that the authors gave much more weight to case-control studies than to cohort studies. That shows an incredible amount of bias in the review.

But even if we think that there is some evidence of a correlation, more scientific work is necessary to show a causal link between a substance and cancer. And this is where many of the studies that claim a link fail.

Biomedical scientists use the Bradford Hill criteria to determine if there is a causal link between something and an effect. Here is that criteria.

  1. Strength (effect size)– this is one of the important parts of this criteria – the larger the effect from the cause, the higher the probability of a causal link. This doesn’t mean small effects aren’t important, it’s just that fields like science-based medicine favor larger effects. The link between talc and ovarian cancer is either nonexistent or very weak, with a tiny effect size.
  2. Consistency (reproducibility) – proposed causality needs to be observed in more than just one location. Consistent data published by different researchers in different locations with different population samples strengthen the possibility that there is a link between a cause and effect. If we look at the studies, they’re all over the place, and better studies show no effect.
  3. Specificity – causation requires a very specific population with a very specific disease with no other possible explanations of that causation. Again, the more specific an association is between cause and effect, the larger the possibility of a causal link. The research does seem to support this point.
  4. Temporality – the proposed effect must occur after the cause, and within a likely time period for which a link between cause and effect. Once again, studies just don’t support this.
  5. Biological gradient – there must be some sort of dose-response effect, that is, the higher the exposure to some cause should generally lead to a higher incidence of the effect. (There are cases where a lower exposure leads to a higher incidence, so we should observe the inverse effect.) None of the studies show a dose-response effect.
  6. Biological plausibility – as we will discuss next, there must be a biologically plausible mechanism between cause and effect. Of course, it is possible that we lack knowledge of all aspects of a biologically plausible mechanism between some cause and effect. Even then, the potential new mechanism must not violate basic principles of biology, chemistry, and physics. Although it is possible that talcum powder was contaminated with asbestos 50 years ago, that is not the case today. Talc is a form of magnesium silicate which has no known link to any cancer – the biological plausibility is simply not there.
  7. Coherence – does the proposed cause and effect fit with what we know about the disease.
  8. Experiment – does a group that lacks exposure to the effect exhibit a different outcome?

Now some may say that “well weak evidence means that there could be a link,” and that is why the jury is right. And that’s where courts and science differ – either there is evidence or not, there’s no “maybe.” The higher quality evidence actually indicates that there is no link, there really is no maybe it causes cancer, it actually says it doesn’t.

The only conclusive way to determine if there is a link would be a large, double-blind clinical trial that controls other factors that might increase or decrease risks of cancer. However, that kind of study suffers from two major issues – one, it’s probably unethical to recruit patients who might be in a group that has a higher risk, and two, even if we don’t think there is an increased risk, it might be hard to recruit patients.

In summary, there does not seem to be high-quality, robust evidence that supports a correlation, and less evidence to support causality. In fact, there is better evidence that shows no link between talc and ovarian cancer. And this is where courts and science are in opposition.

Exposure to chemical in Roundup increases risk for cancer, study finds

Exposure to glyphosate -- the world's most widely used, broad-spectrum herbicide and the primary ingredient in the weedkiller Roundup -- increases the risk of some cancers by more than 40 percent, according to new research from the University of Washington.

Various reviews and international assessments have come to different conclusions about whether glyphosate leads to cancer in humans.

The research team conducted an updated meta-analysis -- a comprehensive review of existing literature -- and focused on the most highly exposed groups in each study. They found that the link between glyphosate and Non-Hodgkin Lymphoma is stronger than previously reported.

Their findings were published this month in the online journal Mutation Research/Reviews in Mutation Research.

"Our analysis focused on providing the best possible answer to the question of whether or not glyphosate is carcinogenic," said senior author Lianne Sheppard, a professor in the UW departments of Environmental & Occupational Health Sciences and Biostatistics. "As a result of this research, I am even more convinced that it is."

By examining epidemiologic studies published between 2001 and 2018, the team determined that exposure to glyphosate may increase the risk of Non-Hodgkin Lymphoma by as much as 41 percent. The authors focused their review on epidemiological research in humans but also considered the evidence from laboratory animals.

"This research provides the most up-to-date analysis of glyphosate and its link with Non-Hodgkin Lymphoma, incorporating a 2018 study of more than 54,000 people who work as licensed pesticide applicators," said co-author Rachel Shaffer, a UW doctoral student in the Department of Environmental & Occupational Health Sciences.

"These findings are aligned with a prior assessment from the International Agency for Research on Cancer, which classified glyphosate as a 'probable human carcinogen' in 2015," Shaffer said.

Glyphosate first was introduced as an herbicide in 1974. Usage in the agricultural industry has soared, particularly since the mid-2000s when the practice of "green burndown" was introduced, in which glyphosate-based herbicides are applied to crops shortly before harvest. As a consequence, crops are now likely to have higher residues of glyphosate.

Researchers say more studies are needed to account for the effects of increased exposures from green burndown, which may not be fully captured in the existing studies reviewed in this new publication.

Co-authors include Luoping Zhang and Iemaan Rana in the Division of Environmental Health Sciences at the University of California, Berkeley, and Emanuela Taioli in the Icahn School of Medicine at Mount Sinai, New York.

Funding was provided by the National Institutes of Environmental Health Sciences award T32ES015459 and the University of Washington Retirement Association Aging Fellowship.

Glyphosate Carcinogenicity Review Published

Recently, concerns have been expressed about the safety of glyphosate. Although hazard analysis by some non-governmental organizations have suggested glyphosate may be carcinogenic, U.S EPA has released its review of glyphosate and concluded that glyphosate is “not likely to be carcinogenic to humans”. This conclusion is consistent with conclusions of other regulatory agencies. The full EPA report is available at this link:

The following summary paragraph is from page 141: “For cancer descriptors, the available data and weight-of-evidence clearly do not support the descriptors “carcinogenic to humans”, “likely to be carcinogenic to humans”, or “inadequate information to assess carcinogenic potential”. For the “suggestive evidence of carcinogenic potential” descriptor, considerations could be looked at in isolation however, following a thorough integrative weight-of-evidence evaluation of the available data, the database would not support this cancer descriptor. The strongest support is for “not likely to be carcinogenic to humans” at doses relevant to human health risk assessment.”

This information has been added to the glyphosate information fact sheet.