Glyphosate and Human Health: What the Research Shows on Cancer, Autism Claims, and Everyday Exposure

In the mid-2010s, a prediction attributed to a senior research scientist at MIT spread widely online: at the current rate, half of all American children would be autistic by 2025, and the widely used weed killer glyphosate was a likely culprit. The claim came from Stephanie Seneff, a computer scientist at MIT’s Computer Science and Artificial Intelligence Laboratory, who had co-authored papers arguing that glyphosate disrupts human biology in ways that could contribute to autism and many other conditions.

2025 has come and gone. The Centers for Disease Control and Prevention’s most recent surveillance estimated that about 1 in 31 eight-year-olds in its monitoring sites had been identified with autism spectrum disorder, a figure that has risen over time largely because of broader diagnostic criteria, increased screening, and greater awareness, but that is nowhere near 1 in 2. The prediction did not come true.

The underlying question, whether glyphosate harms human health, is still a legitimate and active one. It has been the subject of a cancer classification by the World Health Organization’s cancer agency, conflicting regulatory decisions, tens of thousands of lawsuits, and in June 2026 a landmark U.S. Supreme Court decision. This article reviews what the research actually shows, where the scientific disagreements lie, and what individuals can do if they want to reduce exposure.

What Glyphosate Is and How It Is Used

Glyphosate is a broad-spectrum herbicide that kills most plants by blocking an enzyme in the shikimate pathway, which plants use to make certain amino acids. Animals, including humans, do not have this pathway, which is a central reason regulators have considered glyphosate relatively low in toxicity to people. Many bacteria and fungi do use the pathway, a point that has fueled research questions about effects on gut microbes.

Glyphosate was introduced by Monsanto in 1974 under the Roundup brand. Its use rose dramatically after the introduction of genetically engineered, glyphosate-tolerant crops in the mid-1990s, which allowed farmers to spray fields after crops emerged. A 2016 analysis by Charles Benbrook described glyphosate as the most heavily used herbicide in history and estimated that herbicide-tolerant crops account for a majority of its global use. It is also used on non-GE crops, including in some regions as a pre-harvest treatment to dry down cereal crops such as oats and wheat, and widely in forestry, roadsides, parks, and home gardens.

How Much Glyphosate Are People Exposed To?

For most people, the main route of exposure is diet, through residues on food. Farmers, landscapers, and others who mix and spray glyphosate have additional exposure through skin contact and inhalation.

The first national biomonitoring data came from the CDC’s National Health and Nutrition Examination Survey. A 2022 analysis led by CDC scientist Maria Ospina found glyphosate in the urine of about 81 percent of participants aged 6 and older in the 2013–2014 survey. Concentrations were generally low, well below levels regulators associate with health effects, but the near-universal detection confirmed that exposure is widespread. A 2024 study of farmers and non-farmers in the Agricultural Health Study’s biomarker cohort found, as expected, that farmers who applied glyphosate had higher urinary levels than non-farmers.

Diet choices can change exposure. A 2020 study by John Fagan and colleagues in Environmental Research placed families in several U.S. cities on an organic diet for six days and found that mean urinary glyphosate fell by about 71 percent, and its main breakdown product, AMPA, by about 77 percent. The study was small and did not measure health outcomes, but it shows that food is the main exposure source for most people and that exposure can be reduced.

The Cancer Question

The most serious and most studied concern about glyphosate is cancer, particularly non-Hodgkin lymphoma (NHL), a cancer of the lymphatic system.

IARC’s 2015 classification

In March 2015, a working group of the International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic to humans” (Group 2A). Its summary in The Lancet Oncology cited limited evidence in humans for NHL, sufficient evidence in experimental animals, and strong mechanistic evidence including genotoxicity and oxidative stress. IARC classifications describe the strength of evidence that something can cause cancer under some circumstances, not how likely it is to cause cancer at typical exposure levels. Group 2A also includes red meat and night-shift work.

Regulators reach a different conclusion

Regulatory agencies, which assess risk at realistic exposure levels and review a broader set of studies, including unpublished industry studies submitted for registration, have generally disagreed with IARC. The U.S. Environmental Protection Agency has repeatedly concluded that glyphosate is not likely to be carcinogenic to humans. In 2022, a federal appeals court found that EPA had not adequately supported parts of its 2020 human health analysis and sent it back to the agency; EPA withdrew its interim decision and continues its registration review. In Europe, food safety and chemicals agencies concluded that the evidence did not meet the criteria for classifying glyphosate as a carcinogen, and in 2023 the European Union renewed its approval for ten years, with conditions.

Part of the disagreement reflects different questions and different evidence. IARC focused on hazard and gave weight to published studies of formulated products, which contain surfactants and other ingredients besides glyphosate. Regulators focused on risk at expected exposures and relied more heavily on guideline studies of the active ingredient. Critics of the regulatory approach, including a 2016 consensus statement by John Peterson Myers and colleagues in Environmental Health, argued that regulators relied too heavily on industry-funded studies, underestimated exposure, and did not adequately evaluate formulated products.

What the human studies show

Two bodies of human research dominate the cancer debate, and they point in somewhat different directions.

The largest prospective study is the Agricultural Health Study, which has followed licensed pesticide applicators in Iowa and North Carolina since the 1990s. Its 2018 glyphosate analysis in the Journal of the National Cancer Institute, led by Gabriella Andreotti, included 54,251 applicators, of whom 44,932 (82.8 percent) had used glyphosate. It found no association between glyphosate use and cancer overall, including NHL and its subtypes. It did find some evidence of increased risk of acute myeloid leukemia among the most heavily exposed group, which the authors said required confirmation.

A 2019 meta-analysis by Luoping Zhang and colleagues, published in Mutation Research, took a different approach. It pooled studies but focused on the highest exposure categories in each, reasoning that any effect would be most visible among people with the greatest cumulative exposure. It reported that high exposure to glyphosate-based herbicides was associated with a 41 percent increased risk of NHL (meta-relative risk 1.41). A sensitivity analysis produced a similar estimate of 1.45. Critics of the meta-analysis argued that selecting the highest exposure categories from studies with different exposure definitions can inflate estimates; supporters argued it is the appropriate way to detect effects among heavily exposed workers.

For ordinary consumers, the practical significance of this debate is limited. The studies suggesting elevated NHL risk involve heavy, long-term occupational or residential use, such as farmers or groundskeepers mixing and spraying glyphosate products for years. Neither line of research establishes a cancer risk from the small amounts found in food.

The Autism Claims

The claim that glyphosate is driving autism rests mainly on two kinds of argument.

The first is a correlation over time: graphs showing glyphosate use and autism diagnoses rising together since the 1990s. Such graphs show only that two things increased during the same period. Many other things also rose over those years, including organic food sales, internet use, and the number of diagnostic services. Correlation over time, without data on individual exposure and outcomes, cannot establish cause. Autism researchers attribute most of the increase in diagnoses to changes in diagnostic criteria, broader screening, and greater awareness, with genetic factors accounting for a large share of autism risk.

The second is mechanistic speculation. A 2013 paper co-authored by Seneff in the journal Entropy proposed that glyphosate disrupts gut bacteria, enzymes, and nutrient pathways in ways that could contribute to a wide range of modern diseases. The paper presented a hypothesis based on reviewing other literature rather than new experimental data, and it has been widely criticized by toxicologists for drawing sweeping conclusions without direct evidence.

The most relevant epidemiological study is more modest. A 2019 population-based case-control study in The BMJ by Ondine von Ehrenstein and colleagues examined children in California’s Central Valley and estimated prenatal exposure to agricultural pesticides based on applications within 2,000 meters of the mother’s home. It found that prenatal exposure to several pesticides, including glyphosate (odds ratio 1.16), was associated with a slightly higher risk of autism spectrum disorder, with somewhat higher estimates for autism with intellectual disability. The authors framed the results as supporting efforts to limit prenatal pesticide exposure, not as proof that any single pesticide causes autism. Such studies cannot rule out confounding by other factors associated with living near farmland.

In short, there is no credible evidence that glyphosate is a major cause of autism, and the 2025 prediction was not grounded in data. There is limited evidence that residential proximity to agricultural pesticide use during pregnancy, including glyphosate among other chemicals, may be associated with a small increase in risk, which justifies further research and sensible precautions for pregnant people living near heavily sprayed fields.

Other Health Questions

Gut microbiome. Because many bacteria use the shikimate pathway, researchers have asked whether dietary glyphosate could alter gut microbes. Laboratory and animal studies have shown some effects, but whether realistic human exposures meaningfully change the human microbiome, and whether that has health consequences, remains unresolved.

Endocrine and reproductive effects. Some animal and cell studies have reported hormonal effects, particularly from formulated products containing surfactants. Human evidence is limited and inconsistent.

Kidney disease. Glyphosate has been investigated as a possible factor in chronic kidney disease of unknown cause among agricultural workers in Sri Lanka and Central America. Findings have been inconclusive, and heat stress, dehydration, and other exposures are considered important factors.

Formulations versus the active ingredient. A recurring theme is that commercial products contain surfactants and other co-formulants that can be more toxic to cells than glyphosate alone. Regulators have focused primarily on the active ingredient, which critics consider a gap. The EU banned one surfactant, POE-tallowamine, from glyphosate products in 2016.

Health question	Strength of human evidence	Summary
Non-Hodgkin lymphoma (heavy occupational use)	Mixed; most studied	Some meta-analyses find elevated risk at high exposure; the largest cohort does not
Cancer from dietary residues	No evidence of risk	Regulators conclude residues are below levels of concern
Autism	Weak	One study found a small association with prenatal residential proximity to spraying; no causal evidence
Gut microbiome	Preliminary	Animal and lab effects; human relevance unknown
Endocrine effects	Limited	Mostly animal and cell studies, often of formulated products

The Legal Battle and the 2026 Supreme Court Ruling

After IARC’s classification, tens of thousands of people who developed NHL sued Monsanto, and later Bayer, which acquired Monsanto in 2018, arguing that Roundup caused their cancer and that the company failed to warn them. Several juries awarded large verdicts. In 2020, Bayer announced a settlement of roughly $10 billion to resolve a large share of existing claims, while new claims continued to be filed.

The central legal question became whether state failure-to-warn claims could proceed when EPA had approved Roundup labels without a cancer warning. On June 25, 2026, the Supreme Court decided Monsanto Co. v. Durnell. As summarized by Faegre Drinker, the Court held 7–2 that the Federal Insecticide, Fungicide, and Rodenticide Act preempts state-law failure-to-warn claims seeking a cancer warning in addition to or different from the EPA-approved label. The decision overturned a Missouri jury award to John Durnell, who had used Roundup for about 20 years before developing cancer. Legal analysts at Bergeson & Campbell called it the Court’s most significant interpretation of FIFRA’s preemption provision in two decades.

Reactions split predictably. The Breakthrough Institute and agricultural groups said the decision protects farmers’ access to glyphosate and avoids costlier, potentially more harmful alternatives. Justice Ketanji Brown Jackson, joined by Justice Neil Gorsuch, dissented, and plaintiffs’ advocates argued the ruling leaves people harmed by pesticides with fewer remedies. The ruling is a legal decision about who sets warning requirements, not a scientific finding about whether glyphosate causes cancer.

Why Scientists and Regulators Disagree

For many readers, the most confusing part of the glyphosate story is that respected institutions reach different conclusions from overlapping evidence. Several factors explain the split.

Hazard versus risk. IARC asks whether a substance can cause cancer under some circumstances. Regulators ask whether it is likely to cause cancer at the levels people are actually exposed to. A substance can be a hazard without posing meaningful risk at typical exposures.

Which studies count. IARC evaluates only publicly available, peer-reviewed studies and government reports. Regulators also review unpublished guideline studies submitted by manufacturers, which critics say are more likely to favor industry and supporters say are conducted under strict quality standards.

Active ingredient versus product. Many studies that raised concerns tested commercial formulations; regulatory assessments historically focused on glyphosate itself.

How to weigh inconsistent human data. When a large cohort study finds no association and case-control studies and meta-analyses find modest associations among highly exposed people, experts can reasonably disagree about which evidence deserves more weight. Case-control studies can be affected by recall bias; cohort studies can be limited by exposure misclassification and follow-up time.

None of these differences implies bad faith by either side. They reflect genuine methodological choices, which is why the scientific debate has persisted long after the legal one reached the Supreme Court.

Glyphosate in Food: What Testing Shows

Government residue monitoring programs, including USDA’s Pesticide Data Program and FDA’s pesticide monitoring, test foods for many pesticide residues and compare results with legal tolerances set by EPA. Glyphosate is more difficult and costly to test than many pesticides and has been included in these programs less consistently, which critics have pointed out as a gap.

Advocacy groups have commissioned their own tests. The Environmental Working Group, for example, reported in 2018 and later that many oat-based breakfast foods contained detectable glyphosate, sometimes above a benchmark the group set for children, while noting that most levels were below EPA’s legal limits. Industry groups responded that the levels found were far below what regulators consider safe. These tests illustrate that residues are common in some foods, particularly those made from crops that may be treated with glyphosate before harvest, but they also show how the same numbers can be framed as alarming or reassuring depending on the benchmark chosen.

For consumers, the practical takeaway is consistent with the biomonitoring data: exposure is widespread but generally low, and people who want to reduce it can prioritize organic versions of the foods most likely to contain residues.

A Timeline of the Glyphosate Debate

Year	Event
1974	Glyphosate introduced commercially as Roundup and registered in the U.S.
1996	Glyphosate-tolerant GE crops introduced; use rises sharply in following years
2015	IARC classifies glyphosate as probably carcinogenic to humans (Group 2A)
2016	EU bans POE-tallowamine co-formulant in glyphosate products
2018	First jury verdict against Monsanto in a Roundup cancer case; Bayer completes acquisition of Monsanto; Agricultural Health Study reports no association with NHL
2019	Meta-analysis reports 41% higher NHL risk at high exposure; California study links prenatal proximity to spraying with small increase in autism risk
2020	EPA interim decision finds glyphosate not likely carcinogenic; Bayer announces roughly $10 billion settlement of existing claims
2022	Federal appeals court sends parts of EPA’s analysis back; EPA withdraws interim decision; CDC biomonitoring analysis finds glyphosate in about 81% of urine samples
2023	European Union renews glyphosate approval for ten years with conditions
2026	Supreme Court rules 7–2 in Monsanto Co. v. Durnell that federal law preempts state cancer-warning claims

How to Reduce Your Exposure

For people who want to reduce glyphosate exposure, whether out of caution or personal preference, the evidence points to a few practical steps.

Choose organic for crops most likely to carry residues. Organic standards prohibit synthetic herbicides such as glyphosate. The Fagan study showed urinary glyphosate dropping substantially within days of switching to an organic diet. Residues are most commonly associated with crops grown from glyphosate-tolerant varieties and with cereals and legumes that may be treated with glyphosate before harvest in some production systems, so organic oats, wheat products, and legumes are reasonable priorities for people who want to prioritize.

Don’t rely on washing. Rinsing produce removes dirt and some surface residues, but glyphosate is taken up into plant tissues and grain, so washing has limited effect on it.

If you use it at home, follow the label. The highest exposures come from applying products, not eating food. Wear gloves, long sleeves, and eye protection; avoid spraying on windy days; keep children and pets away until the spray has dried; and wash hands and clothing afterward. Choose ready-to-use products over concentrates to avoid mixing.

Consider alternatives for home weed control. Mulching, hand-pulling, flame weeding, and properly used vinegar-based or other contact herbicides can handle many garden weeds without glyphosate, though each has limits, especially against deep-rooted perennials.

For pregnant people near farmland. Given the California findings on residential proximity, it is reasonable to keep windows closed and limit outdoor time during nearby spraying and to ask local agencies or neighbors about application schedules. Many states have pesticide application notification or registry programs.

For workers. People who apply glyphosate occupationally should use recommended personal protective equipment consistently and follow label instructions. Employers are responsible for training and equipment under federal worker protection rules.

What Farmers and Groundskeepers Should Know

The studies that raise the most concern about glyphosate involve people who handle it regularly: farmers, landscapers, groundskeepers, and pesticide applicators. For these workers, the practical steps are straightforward and required by product labels and federal worker protection rules.

Follow the label’s personal protective equipment requirements. These typically include long sleeves and pants, chemical-resistant gloves, and shoes plus socks, with eye protection when mixing concentrates.

Take the most care when mixing and loading. Handling concentrated product carries the greatest risk of skin contact and splashes.

Maintain equipment. Leaking backpack sprayers are a common source of skin exposure.

Wash promptly. Wash hands before eating, drinking, or using the restroom, and wash work clothing separately from household laundry.

Keep records. Records of what was applied, where, and when are useful for both compliance and personal health history.

From an agronomic standpoint, relying on glyphosate alone has driven the evolution of resistant weeds. Extension specialists recommend rotating herbicide modes of action and combining chemical control with cultivation, cover crops, crop rotation, and other practices. Those same practices can reduce total herbicide use, which lowers exposure for workers and communities.

What Comes Next

Several open questions will shape the glyphosate story in the coming years.

EPA’s registration review. After withdrawing its interim decision in 2022, EPA continues to re-evaluate glyphosate’s human health and ecological risks. Its eventual conclusions will determine label requirements, and after the Supreme Court ruling, EPA’s labeling decisions carry even more weight.

Better exposure data. National biomonitoring has so far been limited. More frequent measurements, particularly in children and pregnant people, would clarify how exposure is changing over time.

Long-term cohort follow-up. Continued follow-up in the Agricultural Health Study and similar cohorts will help clarify the possible acute myeloid leukemia signal and whether any NHL risk emerges with longer latency.

Formulations and co-exposures. Research on commercial formulations and combined exposure to multiple pesticides remains thin relative to the attention the topic receives.

Alternatives and trade-offs. If glyphosate use declines, farmers will turn to other herbicides, tillage, or new technologies, each with its own environmental and health profile. Evaluating glyphosate in isolation, without considering what would replace it, gives an incomplete picture.

How to Evaluate Viral Health Predictions

The 1-in-2 autism prediction is a useful case study in judging dramatic health claims. A few questions would have flagged it early.

Is the claim based on data about individuals? Graphs of two trends rising together do not show that the people exposed to one are the people experiencing the other.

Does the speaker work in the relevant field? Expertise in one discipline does not transfer automatically to another. An MIT affiliation does not make a computer scientist an epidemiologist.

Do independent experts agree? Claims that would overturn the consensus of pediatricians, epidemiologists, and toxicologists require strong evidence published in peer-reviewed journals and replicated by others.

Is the prediction specific and testable? This one was, and it failed. That is useful information about the reasoning behind it.

Applying the same questions to reassuring claims is equally important. Statements that glyphosate is “completely safe” can be as oversimplified as claims that it causes most modern disease.

Frequently Asked Questions

Does glyphosate cause autism?

There is no established causal link. A 2014 prediction that half of U.S. children would be autistic by 2025 did not come true. One 2019 California study found a small association between prenatal residential proximity to agricultural glyphosate applications and autism risk, among associations for several pesticides, but it does not establish cause.

Does glyphosate cause cancer?

IARC classified it as probably carcinogenic to humans in 2015, based mainly on limited human evidence for non-Hodgkin lymphoma and animal and mechanistic data. EPA and European regulators have concluded it is unlikely to pose a cancer risk at expected exposures. Evidence of elevated risk, where found, involves heavy occupational use.

How much glyphosate is in my body?

CDC data from 2013–2014 found detectable glyphosate in the urine of about 81 percent of Americans aged 6 and older, generally at low concentrations. Diet is the main source for most people.

Does eating organic reduce glyphosate levels?

Yes. A 2020 study found mean urinary glyphosate fell about 71 percent after six days on an organic diet.

What did the Supreme Court decide in 2026?

In Monsanto Co. v. Durnell (June 25, 2026), the Court ruled 7–2 that federal pesticide law preempts state-law claims requiring a cancer warning beyond what EPA has approved. The decision addressed who sets label requirements, not whether glyphosate causes cancer.

Is glyphosate banned anywhere?

Some countries and many municipalities restrict its use, particularly in public spaces or home gardens. The European Union renewed its approval in 2023 for ten years with conditions.

Should I stop using glyphosate in my garden?

That is a personal decision. If you use it, follow the label, wear protective equipment, and avoid spraying in wind or near children and pets. Many home weed problems can be handled with mulch, hand removal, and contact products, though deep-rooted perennials are harder to control without systemic herbicides.

Is glyphosate in oats and cereal dangerous?

Residues found in testing are generally below EPA’s legal limits. People who want to minimize exposure can choose organic oat and grain products, which are produced without synthetic herbicides.

References

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12. Faegre Drinker. Supreme Court Decides Monsanto v. Durnell. June 25, 2026. faegredrinker.com
13. Bergeson & Campbell. Unpacking the Consequences of the Decision in Monsanto Company v. Durnell. July 9, 2026. lawbc.com
14. The Breakthrough Institute. Supreme Court Ruling Helps Preserve Farmers’ Access to Glyphosate. June 25, 2026. thebreakthrough.org

Last updated: September 26, 2026