When ‘Unexposed’ Doesn’t Exist: Rethinking What Glyphosate Science Needs
Once upon a time, scientists could point to an “unexposed” group of people — those living far from sprayed fields, eating food without residues, drinking water free of agricultural runoff — and compare their health to those who lived and worked among pesticides. That contrast is the backbone of science: without a baseline, it’s hard to know what’s normal, what’s safe, and what’s causing harm.
But when it comes to glyphosate, that baseline is rapidly disappearing. Residues have been found in honey, bread, breakfast cereals, and even in the urine of New Zealand farmers. Overseas studies go further, showing glyphosate turning up in breast milk, drinking water, and the wider environment. Exposure is no longer limited to a few farm workers; it’s in the food chain, in the soil, and in us.
And here lies the problem: if nearly everyone has some glyphosate in their system, who is left to act as the “control group”? Without that comparison, subtle effects — on hormones, gut bacteria, or long-term cancer risk — become harder to detect, easier to dismiss, and far simpler for regulators to wave away as “no conclusive evidence.” In reality, the evidence may be hiding in plain sight, blurred by the fact that we’re all part of the experiment now.
The Pervasiveness of Glyphosate Exposure
Glyphosate-based weedkillers such as Roundup have become so embedded in modern agriculture that avoiding them entirely is almost impossible. Farmers spray them on paddocks to control weeds, councils use them to keep road verges tidy, and they’re routinely applied to staple crops just before harvest to dry them out. The result? Glyphosate doesn’t just stay in the field — it travels with us into kitchens, pantries, dinner plates, and ultimately our gut.
In New Zealand, our own independent testing has found glyphosate residues in honey, bread, and cereals — everyday foods that many families rely on. International research paints a similar picture: Roundup and other glyphosate-based herbicides are now the most widely used weedkillers in the world, and their fingerprints can be found in soil, rivers, rainwater, and even the air. Studies overseas have detected glyphosate in human urine, breast milk, and drinking water, confirming that exposure is no longer a question of if, but how much.
The numbers back this up. In one recent study, glyphosate was found in 96% of New Zealand farmers tested. That’s expected in agricultural workers — but without broader biomonitoring, we don’t know what levels exist in the general population. What we do know is that MPI is considering raising the allowable residue levels on crops like wheat and oats by as much as 9,900%. Instead of reducing reliance on Roundup, regulators are shifting the goalposts higher to accommodate it.
When a glyphosate-based weedkiller like Roundup shows up in staples such as bread, or in products we market as “pure” honey, it’s a clear sign that the chemical has seeped beyond the farm gate. It’s no longer just a farmer’s tool — it’s become a dietary contaminant that none of us asked for, and all of us are being forced to live with.
The Problem with Losing the Unexposed
Science relies on comparison. To understand whether a substance is harmful, researchers look for differences between people who are exposed and those who are not. That “control group” provides the baseline — the benchmark of what health looks like without the chemical in question. But with glyphosate-based weedkillers, that clean baseline is rapidly disappearing.
When glyphosate residues are turning up in honey, bread, cereals, and even drinking water, where do we find the unexposed? If everyone is carrying some level of glyphosate in their bodies, subtle effects — hormone disruption, gut microbiome imbalance, or even long-term cancer risk — become harder to measure. The dose–response curve that scientists depend on gets flattened, and genuine harm can be hidden under a statistical blur.
This lack of a true control group benefits industry and regulators more than the public. When studies show only “weak” or “inconclusive” links, it’s often not because Roundup and similar herbicides are safe, but because we’ve lost the ability to measure the difference. In a world where glyphosate exposure is almost universal, “no evidence of harm” doesn’t mean “proof of safety.” It may simply mean there’s no one left untouched to compare against.
Examples of Masked Effects
The absence of a true control group doesn’t just create a theoretical problem — it has real consequences for how glyphosate-based weedkillers are judged.
Take cancer research. The International Agency for Research on Cancer (IARC) classified glyphosate as a “probable human carcinogen” back in 2015. Yet follow-up studies in farming communities often show only modest or inconsistent links to non-Hodgkin lymphoma. That’s not necessarily because the risk isn’t there — but when almost everyone in an agricultural region has some glyphosate exposure, the difference between “exposed” and “unexposed” groups can all but vanish.
Or consider gut health. Laboratory and animal studies have shown that glyphosate can disrupt the shikimate pathway — a critical system for gut bacteria. Humans don’t have this pathway, but our microbiome does. If most people already carry traces of glyphosate in their system, any subtle shifts in gut bacteria could go unnoticed in population-level studies. The problem isn’t the lack of an effect, but the lack of a clean baseline to measure it against.
Even endocrine disruption — where glyphosate and Roundup formulations have been shown in some experiments to mimic or interfere with hormone signaling — suffers from the same issue. Regulators frequently dismiss these findings as “inconclusive” because human data appear patchy. But if every sample already carries glyphosate residues, “normal” hormone profiles may already be shifted, and the true scale of disruption hidden in plain sight.
In short, the more widespread the exposure, the easier it becomes to dismiss health concerns as unproven. The science isn’t failing — it’s being blurred by the reality that no one is fully unexposed anymore.
The Ethical & Regulatory Implications
If glyphosate-based weedkillers such as Roundup are everywhere, then the burden of proof shifts in a dangerous way. Regulators point to “acceptable daily intakes” and rising maximum residue levels as if these numbers guarantee safety. But those thresholds aren’t fixed truths — they’re policy decisions, often shaped by industry lobbying and trade pressures rather than public health.
Take New Zealand’s proposal to raise allowable glyphosate residues in wheat, oats, and barley by as much as 9,900%. Instead of questioning why residues are climbing in staple foods, officials are simply adjusting the limits upward. It’s a move that makes compliance easier for growers and exporters, but leaves ordinary New Zealanders swallowing more of a chemical already under suspicion.
This raises an uncomfortable ethical question: who benefits when Roundup residues in food are normalized? Corporations protect their markets. Regulators avoid trade disputes. Farmers get a practical tool to manage weeds and speed harvest. But the public becomes the unwitting test group, with no ability to opt out.
When nearly everyone is exposed, waiting for “conclusive human evidence” becomes a Catch-22. Without a clean control group, that proof may never come — and regulators can continue to reassure us that Roundup is “safe” precisely because the science has been blinded by universal exposure.
At some point, the issue stops being just about risk assessment and becomes a question of ethics: do we allow policy to be driven by convenience and profit, or do we act on the precautionary principle when the evidence is blurred but the stakes are high?
What Can We Do Without a Control Group?
If glyphosate-based weedkillers have already spread so widely that no one can be considered “unexposed,” how do we move forward? The answer isn’t to give up on science — it’s to change how we think about research, regulation, and responsibility.
One option is to look for exposure gradients instead of absolutes. Even if everyone has some glyphosate in their system, levels still vary. Farmers and contractors who mix and spray Roundup often carry higher loads than city dwellers, while people who eat more bread, cereals, or imported grains may accumulate more residues than those who avoid them. Comparing across these gradients can help reveal hidden effects.
Another path is biomonitoring. New Zealand currently doesn’t run routine testing of the general population for glyphosate, but other countries do. Urine testing, breast milk analysis, and food residue surveys can all provide valuable data. Without these measurements, we’re flying blind. Independent community testing has already begun filling this gap, but it shouldn’t be left to grassroots campaigns alone.
Most importantly, regulators can act without waiting for perfect proof. The precautionary principle is designed for situations just like this — when uncertainty is high, exposure is universal, and potential harm is serious. Reducing reliance on glyphosate-based herbicides, investing in safer alternatives, and setting stricter residue limits would protect public health even while the science continues to catch up.
And for individuals? Small steps matter. Choosing certified organic or glyphosate-free products, supporting local councils that adopt non-chemical weed control, and backing independent testing initiatives all send a message. If regulators won’t draw the line, then communities can — by refusing to accept that everyone must be a test subject in the Roundup experiment.
A Closer Look at New Zealand
New Zealand is often marketed as “clean and green,” but glyphosate-based weedkillers such as Roundup tell a different story. Residues have already been detected in honey, supermarket bread, and breakfast cereals through independent community testing. These aren’t fringe products — they’re everyday staples found in nearly every household.
Occupational exposure is another piece of the puzzle. A 2022 study found glyphosate in the urine of 96% of New Zealand farmers tested. While agricultural workers are expected to have higher contact, the real gap lies in what we don’t know: there is no routine biomonitoring of the general population. Without that data, we can’t say what “normal” exposure looks like for children, pregnant women, or city residents far from the spray boom.
Meanwhile, regulators are moving in the opposite direction of precaution. The Ministry for Primary Industries has proposed raising maximum residue limits (MRLs) on wheat, barley, and oats by up to 9,900%. Rather than asking why glyphosate residues are so common in staple foods, officials are simply changing the rules to accommodate them.
This regulatory shift matters because New Zealand’s economy depends heavily on trust in our food exports. Countries like Japan have already signaled concern over glyphosate residues in honey, and consumer demand for glyphosate-free products is rising worldwide. By allowing higher Roundup residues, New Zealand risks not only public health at home but also credibility in global markets.
The bigger problem is that these decisions are being made without a genuine control group to measure against. We don’t know what New Zealanders would look like without glyphosate exposure — because such a group may no longer exist. That leaves us making policy in the dark, with trade convenience and corporate interests too often outweighing public safety.
The Risks We Might Already Be Living With
When exposure to glyphosate-based weedkillers such as Roundup is nearly universal, the danger isn’t just what we know — it’s what we may already be missing. If everyone has some glyphosate in their system, then today’s “normal” health patterns may already reflect hidden effects of long-term, low-dose exposure.
Consider hormone disruption. Laboratory research has shown that glyphosate and Roundup formulations can interfere with estrogen and androgen signaling, subtle changes that might not cause obvious illness right away but can set the stage for fertility problems, thyroid disorders, or hormone-related cancers. If those disruptions are widespread, then the baseline itself has shifted, and no one sees it clearly.
The same applies to our gut microbiome. Glyphosate blocks the shikimate pathway, which doesn’t exist in humans but does exist in the bacteria we rely on for digestion and immune function. If gut flora across the population are being slowly reshaped, we could be living with ripple effects on immunity, metabolism, and even mood without realizing glyphosate is part of the story.
And then there’s cancer risk. The International Agency for Research on Cancer labeled glyphosate a probable human carcinogen back in 2015, but regulators continue to reassure the public that evidence is “inconclusive.” What if that’s only because the control group is gone — making it impossible to see clearly that Roundup exposure is part of the rise in conditions like non-Hodgkin lymphoma or colorectal cancer?
The reality is sobering: the absence of a clean control group doesn’t mean we are safe. It means the line between “healthy” and “harmed” may already be blurred, with subtle changes absorbed into what society accepts as normal. By the time those effects become undeniable, they may be so entrenched in our population that reversing them is impossible.
Where This Leaves Us
When glyphosate-based weedkillers turn up in honey, bread, cereals, waterways, and even our bodies, the idea of a clean “control group” becomes a myth. Without that baseline, regulators can hide behind the language of “no conclusive evidence,” even as the true risks are blurred by universal exposure.
But just because the science struggles to measure harm clearly doesn’t mean the harm isn’t happening. It means we’re all part of the experiment now — every family, every community, every generation. That raises a question far bigger than residue limits: do we accept being test subjects for chemical convenience, or do we demand a different path?
New Zealanders don’t need to wait for regulators to act. Communities can push for glyphosate-free schools, councils can adopt safer weed management practices, and consumers can choose products free from Roundup residues. Independent testing — like the work already happening here — is proof that ordinary people can shine a light where official monitoring has failed.
If we want to break free from being part of the glyphosate experiment, the time to act is now. Because the longer we wait, the harder it becomes to see what’s being lost — not just control groups in science, but control over our health, our food system, and our future.
Resources & References
It’s easy for regulators to claim there is “no conclusive evidence,” but that depends on where you look — and what you’re willing to see. The following resources include New Zealand data, international research, and official reports that together reveal how glyphosate-based weedkillers like Roundup have become impossible to ignore.
Characterization of glyphosate and AMPA concentrations in the urine of Australian and New Zealand populations.
Campbell, G. et al. (2022)
Science of the Total Environment
Peer-reviewed study showing glyphosate detected in 96% of New Zealand farmers tested, highlighting occupational exposure.
IARC Monograph Volume 112: Glyphosate.
International Agency for Research on Cancer (IARC). (2015)
The IARC classified glyphosate as a “probable human carcinogen,” sparking global debate about Roundup’s safety.
Proposed amendments to the New Zealand Food Notice: Maximum Residue Levels for Agricultural Compounds.
Ministry for Primary Industries (MPI). (2025)
Government proposal to raise allowable glyphosate residues in staple grains by up to 9,900%.
Expert reaction to proposed increase in glyphosate limits.
Science Media Centre (NZ). (2025)
Summarises scientific and public health concerns over MPI’s plan to increase MRLs.
Submission opposing higher glyphosate residue limits.
Soil & Health Association NZ. (2025)
Argues that raising MRLs undermines food safety, risks trade, and ignores long-term health concerns.
Independent testing results: Supermarket Bread
No More Glyphosate NZ. (2025)
Community-funded testing shows glyphosate residues in everyday foods, filling the gap left by official monitoring.
Health risk assessment of glyphosate for the Ministry of Health.
ESR (Institute of Environmental Science & Research). (2014)
New Zealand report assessing glyphosate health risks, focused mainly on acute rather than long-term exposures.
Long-term exposure to low doses of glyphosate-based herbicides: a 2-year integrated study on rats.
Ramazzini Institute (2025)
One of the most comprehensive independent studies showing endocrine, reproductive, and genotoxic effects at levels far below regulatory thresholds.
Hypothesis: glyphosate-based herbicides can increase risk of hematopoietic malignancies through extended persistence in bone.
Benbrook, C. (2025)
Environmental Sciences Europe
Proposes a mechanism by which glyphosate may accumulate in bone and marrow, prolonging exposure of stem cells and raising risk of blood cancers like non-Hodgkin lymphoma.
Peer review of the pesticide risk assessment of glyphosate.
European Food Safety Authority (EFSA). (2023)
Concluded “no critical areas of concern” — yet flagged numerous data gaps, illustrating how regulatory interpretations often soften scientific uncertainties.
The studies and reports above don’t all agree — and that’s exactly the point. Regulators highlight “no concern,” while independent scientists uncover disruption at doses far below official limits. The absence of a clean control group makes certainty elusive, but it doesn’t erase risk. The real question is: how much uncertainty are we willing to live with when Roundup residues are already in our food, water, and bodies?
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