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Dr. Robin Mesnage is a Research Associate in the Department of Medical & Molecular Genetics at King's College in London. For more on the importance and implications of this research, see our FAQ and  guest blog by pediatrician and HHRA Science Advisory Board member Dr. Michelle Perro.

Archived HHRA News Posts
  • Spraying Pesticides HHRA Answers DPR’s Call for Comments on Its “Roadmap” for Transforming Pest Management

    In a January 26, 2023 press release, the California Department of Pesticide Regulation (DPR) released a provocative report entitled “Sustainable Pest Management: A Roadmap for California.” The Roadmap report sets “ambitious goals and actions to accelerate California’s systemwide transition to sustainable pest management and eliminate prioritized high-risk pesticides by 2050.” Also by 2050, the Roadmap report envisions that “Sustainable pest management has been adopted as the de facto pest management system in California.” The report captures the ideas and input of a diverse stakeholder group that met over two years to help DPR, Cal-EPA, and the California Department of Food and Agriculture develop a comprehensive plan sufficient to transform agriculture in the State from often heavily-pesticide dependent management systems to systems grounded in pest-prevention, biological control, and reduced-risk biopesticides. The Roadmap identifies and addresses most of the factors shaping pest management systems in the State and calls for dozens of new research, education, training, and regulatory initiatives. In order to guide the implementation process, DPR requested comments from the public that were due March 13, 2023. In crafting HHRA’s comments, Chuck Benbrook and Mark Lipson drew on their decades of experience tracking and advising DPR on pesticide use and regulatory issues.

  • HHRA Paper Analyzes Pesticide Dietary Risk in Individual Samples of Foods

    One of the main sources of pesticide exposure is through  the diet. It is critically important to understand pesticide residues in foods and how dietary risks have changed over time. Over the last 20 years HHRA’s Executive Director Charles Benbrook has developed an analytical database that quantifies the relative risk posed by residues in the diet. Known as the Dietary Risk Index (DRI), this  system was created to help researchers compare risk levels across foods and pesticides, track changes in dietary risk over time, and assess the impact of where food is grown on residues and risk levels, as well as how production systems influence residues and risks (conventional versus organic). The DRI combines the results of United States and United Kingdom pesticide residue testing programs with data on food serving sizes and each pesticide’s chronic Reference Dose or Acceptable Daily Intake. Chronic DRI values are a ratio: the amount of residue in a serving of food relative to the maximum amount allowed by regulators. DRI values are a ratio: the amount of residue in a serving of food relative to the maximum amount allowed by regulators. Data generated by the DRI helps guide HHRA’s policy and public health by highlighting which food-pesticide combinations account for the most worrisome risks in the food supply. The DRI system initially reported aggregate values for a given food/pesticide combination. These values are derived from multiple individual samples of a food collected by regulatory agencies.  For these DRI values, each individual number represents many servings of a given food. In 2022, HHRA added additional functionality the the DRI to report dietary risk in individual samples of a given food. The paper “Tracking pesticide residues and risk levels in individual samples—insights and applications,” which was published in the peer-reviewed journal Environmental Sciences Europe in July 2022, describes the methodology and data sources used to calculate these individual sample DRI values, and highlights some of the results and what they can tell us about residue levels in the global food supply. This is the first analytical system worldwide to provide this level of insight into residues in food. As the paper reports, “dietary risk levels are highly skewed. A large number of samples pose moderate, low, or very-low risks, and relatively few samples pose high or very-high risks.” Thus, regulators and researchers can use the DRI to pinpoint where pesticide dietary risks needs to be mitigated. Like all of HHRA’s peer-reviewed publications, this paper is open access and available free of charge. Click here to view the full text. Access DRI data here.

Archived Blog Posts
  • A man spraying pesticides California’s Bold Plan to Transform Pest Management Systems is Long on Ambition and Light on Details

    By: Chuck Benbrook, HHRA ED By: Mark Lipson, HHRA Director of Policy and Regulatory Engagement We welcomed the invitation from California’s Department of Pesticide Regulation for members of the public to offer comments and guidance as the State begins to take concrete actions needed to achieve the goals set forth in the new report Sustainable Pest Management: A Roadmap for California. Reviewing the 94-page Roadmap report reminded us how many constituencies, forces, and factors are pushing and pulling farmers, pest managers, and government agencies in multiple directions that are rarely aligned. This Roadmap document describes a very different pest management future that will hopefully become the “de facto” way pests are managed on and off the farm by 2050. If successful by 2050, prevention-based biointensive Integrated Pest Management (bioIPM) will be the norm and there will be minimal if any use of high-risk “Priority Pesticides”. Some thirty-two years ago, DPR hired Chuck Benbrook to carry out a comprehensive evaluation of DPR’s programs and policies to assist in the integration of DPR into the newly-formed Cal-EPA. The resulting report, Challenge and Change: A Progressive Approach to Pesticide Regulation in California, came out in March of 1993. It provides dozens of recommendations intended to do many of the same things that the 2023 Roadmap report hopes to bring within reach. The fact that most pest management systems in California have become more, not less reliant on pesticides over the last 30 years suggests that DPR’s and CDFA’s efforts to achieve Roadmap goals are going to entail heavy lifting, mostly uphill. For this reason in HHRA’s comments, Mark and Chuck describe the nature and substantial scope of changes in laws and policy that will be required to track progress toward Roadmap goals and hopefully, someday, achieve them.

  • Europe is Growing Organic Production, Will the US Follow Suit?

    Advocates calling for change in US Ag Inc often struggle to point to successful models through which farming and food chains have evolved toward safer and more sustainable production systems. The surest way to largely eliminate the impacts of prenatal pesticide exposure on birth outcomes and children’s development – HHRA’s foundational goals – is converting US farmland to organic production. We are often asked how such change can come about. Convincing answers to this key and important question are few and far between in the US, but some key lessons are emerging from efforts in Europe to expand organic farming and food supply chains. The Cilento organic food bio-district in Italy was established in 2009 and is thought to be the first-ever in the world. Overcoming challenges faced by organic farmers in marketing their produce was a primary driver. Municipal actions expanded demand for organic food and ingredients via public food-purchasing programs. The lure of scenic rural landscapes and strong support from the agrotourism industry for organic food and farming created new market demand. Today, organic farming is thriving in the Cilento district, profit margins have expanded, and enhanced soil health is supporting higher yields at lower costs on many farms. An action by a city council led to the formation of the Södertälje organic food system in east-central Sweden, some 35 kilometers from Stockholm. The goal was to expand the supply of organic products for public food-procurement programs as a way to advance health and environmental quality. The municipality’s Diet Union developed new food products and recipes in the context of a “Diet for a clean Baltic” to promote health and reduce food waste. Restaurants and cafeterias began using smaller plates to cut down on waste, an intervention that has proven to be surprisingly effective. In south-eastern France the mad cow disease outbreak across Europe was the trigger of action leading to the Mouans-Sartoux organic food system. The initial focus was on supplying organic beef to school canteens, coupled with municipal government support for regional sustainable farm research and food education programs. A multi-faceted effort to provide organic food to children led to greater awareness of the diversity of benefits arising from organic farming. New efforts emerged to reach other vulnerable segments of the population with organic food (e.g. the elderly, pregnant women). These three region-based organic food systems in Europe are case studies in a just-published paper by Lilliana Stefanovic (2020), a scientist in the Department of Organic Food Quality and Food Culture at the University of Kessel in Germany. Imagine that. An academic department focused on organic food quality and culture. How long might it take for such a department to take hold at Iowa State University, in the heart of American farm country? The Stefanovic paper addresses how local organic food systems in Europe can contribute in achieving the Sustainable Development Goals (SDG) set forth by the United Nations, and especially SDG 12, “responsible consumption and production.” Her analysis concludes that local and place-based organic food and farming districts can make important contributions in transforming food and farming systems to promote human and animal health, and soil health and environmental quality. Two drivers played key roles in all three case studies: relatively short distances to population centers, and significant support for organic supply chains from public food-procurement programs, and especially those feeding children. And just a few months ago, the Italian government pledged to invest 3 billion euros (about $3 billion US) to convert at least 25% of the country’s farmland to organic systems by 2027. The funds will come from Common Agricultural Policy payments supported in part by a tax on pesticide sales. There are about 16.6 million acres of arable land in Italy. Reaching the 25% organic goal would entail the transition of around 2 million more acres to organic, given that a little over 15% of Italian farmland is already managed organically. If $3 billion in transition payments were spread over 2 million acres, average payments would be around $1,500 per acre. A multi-pronged effort in Italy is planned to simultaneously grow the supply of organic foods and demand for them. Investments will be made in the infrastructure needed to support profitable regional organic food supply chains, while increasing the supply of value-added, premium foods for sale throughout Italy, Europe, and for a few commodities (especially olive oil), the world. Such bold pledges and audacious goals have come and gone in many countries with little concrete and sustained change to show for the resources invested. But perhaps the time is right in Italy for acceleration in the transition to organic farming in light of the many scientific studies showing that organic farming can both slow global warming and render farms more resilient in the face of drought and flooding. What about here in the USA? The USDA has recently pledged to invest $300 million in a new Organic Transition Initiative. This program will provide new funding via many USDA-program channels to encourage the transition of farms to organic production. While a major increase in USDA funding dedicated to expanding organic production, $300 million over several years is a small share of the approximate $20 billion in annual federal spending on farm commodity and crop insurance programs. It is also instructive to compare the $3 billion investment in Italy to reach their goal of 25% of farmland in organic by 2027 to the $300 million investment just announced by USDA. The Italian program, if it actually happens, would provide about $1,500 per acre transitioned to organic. The USDA’s investment of $300 million translates into about $4.30 per acre across the approximate 70 million newly transitioned acres necessary for 25% of the US cropland base to be managed organically. Current disparity in public support for and investment in the transition to organic farming in the US versus Europe arises from vastly different public awareness of the benefits likely to stem from the transition of more farmland to organic production. Many public and private institutions […]

Guest Blog: Dr. Robin Mesnage on Groundbreaking Glyphosate-Microbiome Study

Jan 26th, 2021
Dr. Robin Mesnage is a Research Associate in the Department of Medical & Molecular Genetics at King's College in London. For more on the importance and implications of this research, see our FAQ and  guest blog by pediatrician and HHRA Science Advisory Board member Dr. Michelle Perro.

By: Robin Mesnage, PhD

Our gut is home to trillions of bacteria which are critical to good health. Because the once-in-a-century herbicide glyphosate can kill bacteria in a petri dish, the notion that glyphosate acts as an antibiotic in the human gut, and as a result is causing human disease, has gained prominence. However, whether and how glyphosate affects the gut microbiome is still an open question. It is what prompted me a few years ago to switch my research focus to the study of the effect of glyphosate on the gut microbiome.

Together with my group leader Dr. Michael Antoniou at King’s College London, we have put together an international team of scientists based in London, France, Italy, and the Netherlands. We have carried out the first in-depth animal study on the impact of glyphosate on the gut microbiome. After three years spent conducting the experiment and crunching numbers on glyphosate’s impacts on the rat microbiome, our findings have been published in Environmental Health Perspectives the 27th of January, 2021.

The Microbiome and Gut-Brain Connection
The gut microbiome contains billions of cells that we are learning play an important role in our physical, and even mental, health.

Let’s dive into our results. First, did glyphosate act as an antibiotic? The short answer is no. In order for glyphosate to act as an antibiotic, it needs to cause a significant shortage in the production of compounds in bacteria called aromatic amino acids. This is how glyphosate kills plants. More specifically, it interrupts a series of chemical reactions within the shikimate pathway.

We reveal for the first time that glyphosate does inhibit the shikimate pathway in the rat gut microbiome. However, glyphosate likely did not kill bacteria via its impact on the shikimate pathway, because bacteria do not need the shikimate pathway to get the aromatic amino acids they need. Like us, they get them from the food we eat.

Glyphosate’s impact on the shikimate pathway had other consequences. A multitude of small molecules (metabolites) accumulated, while others were depleted in the rat gut. The bacterial composition of the gut microbiome also changed, with some bacteria present at higher levels in the glyphosate exposed animals.

We have an explanation for this: the glyphosate molecule contains one atom of phosphorus, and it is very likely that this phosphorus was used as a source of energy by some bacteria to proliferate in the rat gut. It is not clear whether the changes caused by glyphosate in the gut were pathological. However, these changes are a reflection of impacts that can serve as a biomarker to detect whether glyphosate is having an effect on the gut microbiome in humans.

We had another important question to answer: did glyphosate’s impact in the gut stay in the gut? We evaluated this by tracking whether the changes in gut microbiome chemistry caused changes in blood composition.

The compounds altered as a consequence of the interruption of the shikimate pathway by glyphosate in the gut were mostly unchanged in blood. However, other chemicals had their levels disrupted by glyphosate, with some indicating that glyphosate caused oxidative stress.

Roundup Bioflow is the predominant glyphosate formulation in Europe.

Oxidative stress is produced when free radicals are created in such quantities that the body’s defense mechanisms are overwhelmed and cannot prevent damage to cells and DNA — the building blocks of our bodies. It is not fully clear if this oxidative stress is due to the action of glyphosate in the gut microbiome, although our results indicated that Roundup caused a depletion in protective compounds such carotenoids in the gut microbiome that could potentially explain this oxidative stress.

This oxidative stress was even more pronounced when we tested a commercial herbicide containing glyphosate called Roundup Bioflow (also known as MON 52276, the representative glyphosate herbicide in the EU that regulators are focusing on).

It is possible that the altered molecular profiles we observed could serve as a biomarker to better understand if oxidative stress is impairing the health of agricultural workers exposed to glyphosate.

What are the next steps? It is not clear whether the changes caused by glyphosate in the gut were pathological. This study is a first step, and we hope that our new findings will be used as a foundation by other scientists to make new studies.

We are conducting more studies at the moment to understand if this oxidative stress caused by glyphosate is also damaging DNA, and hence raising the risk of cancer. This work will progress through collaborations with The Heartland Study, the Heartland Health Research Alliance [click here to sign up for updates from HHRA], and the Ramazzini Institute. To be continued!


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