In February last year a group of international scientists published a consensus statement drawing attention to the risks posed by rising levels of exposure to glyphosate-based herbicides (GBHs), especially in the light of glyphosate’s classification by the World Health Organization’s cancer agency IARC as a probable carcinogen. The scientists noted endocrine (hormone) disrupting effects of glyphosate herbicides in test-tube experiments and called for more studies to clarify whether levels present in foods and the environment can cause such effects in living humans.
Endocrine disruptors (EDs) have harmful effects on experimental mammals that are widely used as human surrogates at concentrations as low as parts per billion (ppb) and below.
Later in the year, the New York Times reported that GM glyphosate-tolerant crops have significantly increased the use of glyphosate-based herbicides in the US. This news was closely followed by the publication of a report by Food Democracy Now and the Detox Project showing high levels of glyphosate residues in popular foods and drinks.
Given the increasing risk to people posed by EDs, you’d expect regulators to be eager to take action. But sadly the opposite is true. The European Commission has been so tardy in regulating them that the European Court of Justice has declared that it has “unlawfully refrained from laying down rules”.
This issue of GBH exposures has gained urgency from a new study in rats, which showed that Roundup caused fatty liver disease at the minute concentration of 0.1 ppb given in drinking water over a long-term period. The glyphosate daily intake level from this dose was 4 nanograms per kilogram of bodyweight per day, which is 75,000 times below EU and 437,500 times below US permitted levels. The concentration of glyphosate in the drinking water (50 parts per trillion) was 14,000 times less than the concentration allowed in US drinking water (700 ppb).
Tests have shown that most Americans have glyphosate in their urine at ppb levels, suggesting a daily intake of around 1000-fold above the level that caused fatty liver disease in the rats. However, further research needs to be done to establish the glyphosate levels present in various body tissues, especially within endocrine organs like the pancreas.
It’s not certain that the fatty liver disease reported in the Roundup-fed rats was caused by the mechanism of endocrine disruption. But given the extremely low dose of Roundup that caused the effect and the known association between EDCs in general and non-alcoholic fatty liver disease, endocrine disruption is one plausible mechanism. These observations call for urgent further research to be conducted to confirm Roundup/glyphosate-induced organ toxicity at real world levels of ingestion, and to provide insight into the mechanisms of toxicity, including ED effects.
Glyphosate herbicides and endocrine disruption
In 2009, the International Endocrine Society issued its first warning about the dangers associated with chemicals that interact with, take the place of, or inhibit or stimulate the action of natural human hormones (EDs). Today, based upon highly credible research published in peer-reviewed journals by scientists around the world, there is little doubt that GBHs are endocrine disruptors at the relatively high doses tested thus far. Their endocrine activity at low, realistic doses is still uncertain and requires further research.
According to the International Endocrine Society, there is strong mechanistic and epidemiological evidence that endocrine disruption plays a role in a wide range of maladies, including obesity, non-alcoholic fatty liver disease associated with diabetes, female and male reproduction abnormalities (abnormal sperm and reduced fertility), hormone-sensitive cancers in females, prostate cancer, thyroid diseases, and neurodevelopment diseases (IQ loss and hyperactive behaviour).
Scientists have calculated that in the US alone, pesticide EDs cause some 7,500 annual serious disability cases and generate annual medical and lost work costs of about $45 billion. A study (covering some endocrine disruptive chemical (EDC)-associated diseases within the European Union puts annual costs to health services within this region at €150 billion per annum and some $340 billion in the US.
Major international and national health and science institutions have recently documented their concerns about EDs, which include a need for improved testing, education, and research, as well as updated detection protocols and reduced exposures. These concerns have been expressed by the American Medical Association, American Public Health Association, the American Chemical Society, the International Endocrine Society, and the World Health Organization, among others.
Use of endocrine disruptors should be suspended
Accordingly, I am of the firm belief that use of EDs – potentially including GBHs – should be suspended until thorough, transparent, and mathematically robust human epidemiological toxicology analyses are carried out by an international panel of respected scientific experts. The panel members should be chosen by other academic scientists and not involve industry or government participants. An analysis by the International Agency for Research on Cancer (IARC) has already linked glyphosate exposure with cancer in humans. Yet apparently this is not sufficient evidence to end the use of GBHs.
I am not aware of any robust epidemiology studies investigating the possible effects of GBH exposures on endocrine-related diseases such as cancer, IQ loss, thyroid hormone perturbations, and organ changes. As stated in the international scientists’ consensus statement on glyphosate and its formulations, there are large gaps in our knowledge about such effects and more studies need to be carried out. Of course the absence of such published research is not a sign that GBHs do not cause endocrine effects. We have the technology and the scientists to do such work – but the latter apparently lack financial support and/or are worried about industry criticism and intimidation if the results show that GBHs should be banned.
Such additional studies of course will take time. In the meantime American farmers are fighting the failures of glyphosate technology to control weeds, with a concomitant loss of crop yields and farm profits. Industry's answer is to invoke the pesticide treadmill concept and tell farmers to use more pesticides, including GBHs, plus one or two other pesticides at the same time. These pesticides include probable carcinogens and/or endocrine disruptors, such as 2,4-D, isoxaflutole, neonicotinoids, and fungicides like triflumizole.
While selling more pesticides makes good business sense for the industry, for farmers and consumers it means increasing exposures and potentially serious environmental and health impacts. Little or no toxicological data are publicly available on the combined effects of GBHs when mixed with these other known toxic pesticides. This situation should worry everyone.
Short of a universal ban on GBHs in order to protect consumers who are exposed to and consume glyphosate in their food and drink, glyphosate applications should be highly restricted to approved licensed applicators only, under conditions of extreme agricultural need.
What good is it anyway to make multiple applications of GBHs when weed resistance is already a major problem? The only one to benefit is the industry that wants to sell the product. In this context regulators worldwide have steadily increased the allowable levels of glyphosate residues in crops and foods, apparently to accommodate increased levels of glyphosate being found in GM glyphosate-tolerant soybeans.
Such decisions do not enjoy public support, especially from those of us who believe that glyphosate herbicides do harm, may be endocrine disruptors, and are biologically active at levels commonly found in human urine.
Cigarette smoke, PCBs – and glyphosate herbicides
Industry claims that glyphosate is "safe" are reminiscent of similar claims made in the past over cigarette smoke, DDT, PCBs, thalidomide, diethylstilbestrol (DES), Agent Orange, atrazine, flame retardants, phthalates, bisphenol A, and artificial fragrances – all of which are endocrine disruptors.
Consumers are confused, and some are angry and frustrated with regulatory decisions dealing with the biosafety assessment of many commercial products. At the very least many of us feel that the influence of industry has been too strong in regulatory decisions.
Non-industry scientists should test chemicals for regulatory purposes
In the US, a series of poor regulatory decisions – such as allowing the continued use of atrazine, a toxic herbicide banned in Europe many years ago – have set up the EPA for continuing criticism, political and budgetary punishment, and, heaven forbid, talk of abolishing the agency.
It is long past time for the US Congress to change the rules that now require industry to study and report risk evaluations to regulators prior to sale of new chemicals. Realities dictate that the opposite should be the case; i.e., regulators and government or academic scientists should conduct and study chemical safety parameters and report the independent results to industry. Funding for such determinations could come from an industry registration tax for each chemical being registered.
Consumers need and deserve better action from regulatory agencies to protect the health of our children and grandchildren and the environment they will inherit.
Today we need to know why the US EPA and other regulators around the world continue to make what many scientists and members of the public feel are decisions that lack common sense. In the US, I believe that we need publicly visible, politically courageous investigations within regulatory agencies, perhaps conducted by the Office of Inspector General, to attempt resolution of these crucial matters that affect the everyday lives of people around the world. Such legal investigations may be the only remaining hope to create strong, stable environmental agencies staffed with brave and courageous scientists and regulatory personnel who earn the support of their constituents through transparency, independence from industry, and common-sense regulatory decisions.
Dr Ramon Seidler, PhD, is a retired senior research scientist and Team Leader of the Genetically Engineered Organism biosafety program within the US EPA and former Professor of Microbiology at Oregon State University.
Image: Dr Ramon Seidler holds a jar of GM maize. In 2016 89% of the US corn acreage was herbicide-tolerant and most of this will be tolerant to glyphosate herbicides.