Despite mounting evidence of serious health risks, the U.S. continues to allow diquat use on farms.
In the United States, diquat is used everywhere—from the potato fields of the Pacific Northwest to the watersheds of New England and the weeds wilting along suburban sidewalks. Approved by the Environmental Protection Agency (EPA), this fast-acting herbicide remains a go-to chemical for farmers and home gardeners. A growing body of scientific research, however, has highlighted the harmful effects resulting from its widespread use.
Studies have linked diquat to organ damage, reproductive harm, and ecological destruction—from fish and birds to the microbes that keep the soil alive. These concerning facts have led the European Union, the United Kingdom, and several other countries to ban the chemical outright. So why is it still being sprayed so freely in the U.S.?
Diquat is widely used across the U.S. as a herbicide and desiccant, particularly for drying out crops like potatoes, soybeans, and cotton before harvest. It is also applied to manage invasive aquatic plants in lakes, rivers, ponds, and canals, as well as to control broadleaf weeds in orchards and vineyards, and for general weed control. Despite its known toxicity, diquat is used in lawn care products sold at major retail outlets across the U.S., putting potent toxins within easy reach of unsuspecting consumers.
The European Commission decided to ban diquat in 2019 after the European Food Safety Authority concluded that it posed high risks to bystanders, residents, and birds and did not meet the required safety criteria. Despite the serious concerns raised about the use of diquat by international reviews, including worker exposure levels exceeding acceptable levels even with protective gear, the EPA has not initiated any comparable reevaluation of diquat use in the United States since 2002.
Diquat’s ubiquity in the U.S. (it was first approved by the EPA in 1986) reflects a complex web of regulatory gaps, industry influence, and uneven global standards. The herbicide continues to be marketed and exported by some of the very nations that now refuse to use it themselves.
Moreover, its toxic legacy—ranging from sickened farmworkers in Latin America to the quiet unraveling of soil and aquatic ecosystems—exposes the “hypocrisy” of governments and large corporations who continue to support the trade and use of this deadly chemical in our food systems. It also shows how little most consumers know about the chemicals used not just on farms, but also in their backyards.
“Other countries have banned diquat, but in the U.S., we’re still fighting the fights that Europe won 20 years ago,” Nathan Donley, environmental health science director for the Center for Biological Diversity, told the Guardian in 2025. “It hasn’t gotten to the radar of most groups, and that really says a lot about the sad and sorry state of pesticides in the U.S.”
As regulatory gaps widen, diquat’s story highlights uncomfortable truths about accountability, transparency, and who ultimately bears the cost of chemical-intensive agriculture and lawn care. Amid growing concerns over its long-term impacts, diquat is an example of how chemical safety standards can diverge sharply across borders, often with little consumer awareness.
In the wake of growing controversy surrounding glyphosate—the active ingredient in Monsanto’s (now Bayer’s) Roundup—being a “public health hazard,” diquat has increasingly emerged as a substitute herbicide, both in agricultural settings and consumer lawn products. In response to multiple lawsuits and public concern over glyphosate’s alleged links to cancer, Bayer announced in 2023 that it would begin reformulating certain Roundup products for the U.S. market. In place of glyphosate, some new formulations now feature alternative active ingredients, including diquat dibromide.
In 2024, the nonprofit Friends of the Earth (FOE) published the report “New Roundup, New Risks,” to evaluate the new formulations currently being sold in Lowe’s and Home Depot in the United States. The FOE analysis found diquat overall to be “200 times more chronically toxic” than glyphosate in terms of chronic exposure. FOE identified eight Roundup products in which Bayer has replaced glyphosate with combinations of four different chemicals, including diquat dibromide, fluazifop-P-butyl, triclopyr, and imazapic. “All four chemicals pose greater risk of long-term and/or reproductive health problems than glyphosate, based on the EPA’s evaluation of safety studies,” according to FOE’s analysis, which noted “the new Roundup formulations are 45 times more toxic to human health, on average, following chronic, long-term exposure.”
“From a human health perspective, this stuff is quite a bit nastier than glyphosate, so we’re seeing a regrettable substitution, and the ineffective regulatory structure is allowing it,” said Donley.
Diquat-based herbicides are sold under several well-known brand names in the U.S., including Reglone, Reward, and Tribune. Reglone, originally developed by Imperial Chemical Industries and now marketed by Syngenta, is primarily used as a crop desiccant. In aquatic and turf management, Reward and its generic counterpart Tribune (both containing diquat dibromide) are commonly used to control invasive pond and lake weeds.
Long-term or repeated low-level exposure to diquat has been linked to serious health issues, including organ damage. It is also thought to be a neurotoxin and carcinogen and has been linked to Parkinson’s disease. A May 2025 study published in Frontiers in Pharmacology found that diquat can damage the gut barrier, which plays a critical role in immune function and nutrient absorption. Animal studies have raised concerns about potential neurological impacts, with some evidence suggesting oxidative stress and damage to brain cells similar to that seen in paraquat herbicide exposure—although this area requires further study. Research also points to reproductive toxicity, including harm to sperm quality and fetal development in mice.
As a bipyridyl compound, diquat shares structural and functional similarities with paraquat, a highly toxic chemical first produced for commercial purposes in 1961.
Since Brazil banned paraquat in 2020, diquat use surged by 1,600 percent between 2019 and 2022 as a replacement, leading to increased exposure among agricultural workers. According to a 2024 article in Greenpeace-operated publication Unearthed, reports have surfaced of “acute pesticide poisoning,” including symptoms of blurry vision, numbing sensation, and temporary paralysis.
While studying the effects of diquat on farmworkers, EU safety officials set up a “modeled scenario” using tractor-mounted equipment and found that “worker exposure would exceed the maximum acceptable level by more than 4,000 percent—even if the farmworker was wearing personal protective equipment (PPE),” the Unearthed article stated.
Exposure to high doses of diquat can lead to a rapid onset of severe symptoms, according to scientific research. “While laboratory experimentation has suggested that diquat is not directly neurotoxic, there have been relatively consistent pathologic brain changes noted in reported fatal cases of diquat poisoning. These consist of brain stem infarction,” according to the EPA.
Diquat’s ecological footprint extends beyond its intended target, posing harms to soil health, aquatic ecosystems, and wildlife. The mobility and stability of the herbicide can vary significantly depending on the environmental context, with rapid removal seen in some settings and persistence under others.
“In soil, diquat is easily adsorbed onto soil particles, resulting in low mobility and slow degradation, primarily relying on microbial and chemical processes for breakdown,” states the Frontiers in Pharmacology study. However, noting that while its “degradation rate is relatively fast, the degradation products may pose secondary toxicity to aquatic organisms, long-term threats to organisms and ecosystems in the environment.” Other research suggests that acute diquat exposure can result in toxicity, and its presence in waterbodies can lead to it being “accumulated in aquatic organisms,” becoming a high burden to them. “As an aquatic herbicide… diquat induced potential risks to non-target aquatic organisms are considerable,” stated a 2024 study in Scientific Reports, adding the need for stringent policymaking for the use of such chemicals.
Another 2010 study published in the Philosophical Transactions of the Royal Society B studied the effect of diquat on freshwater snails. It concluded that even “low diquat concentrations… may induce significant adverse effects on hatching rate, embryonic stage duration, juvenile mortality rate and age at maturity in the freshwater snail L. stagnalis.”
Diquat’s continued use is driven in part by powerful industry actors and uneven global regulations. Chemical manufacturers—most notably Syngenta, one of the world’s largest agrochemical firms—play a central role in the worldwide production, marketing, and continued use of diquat. While Syngenta ceased selling diquat in the European Union following the 2019 ban, the company continues to export the chemical to countries where regulations are less stringent, according to a 2018 article in Politico, which noted that investigations have revealed that Syngenta lobbied against tighter pesticide regulations in Europe before the ban.
Moreover, while diquat is banned in Switzerland, Syngenta’s headquarters, this has not stopped the company from selling its product to other poor countries. “Although it was banned in the EU… diquat remains a top export. In 2023, Syngenta exported over 8,500 tons of banned pesticides from the UK, with diquat-based products making up the majority,” pointed out a May 2025 article by the Slow Food Foundation.
This dual standard underscores a broader trend in the agrochemical industry, where companies shift toxic products away from high-regulation markets while maintaining global profit streams, raising ethical questions about environmental justice and chemical safety in lower-income countries.
A 2020 investigation by Unearthed and Public Eye, a Swiss nonprofit, revealed the “abhorrent’ trade in pesticides” by Europe and the UK to poor countries, noting, “Loopholes in European law mean chemical companies like Bayer and Syngenta can continue making pesticides for export long after they have been banned from use in the EU to protect the environment or the health of its citizens.” Campaigners in the importing countries have highlighted this “double standard,” “which placed a lower value on lives and ecosystems in poorer countries,” according to the Unearthed investigation report.
Meanwhile, a 2024 investigation by Unearthed and Public Eye revealed the continuation of these exports to poor countries. A Syngenta spokesperson justified the company’s actions by saying that agricultural needs differed around the world and the “use of agrochemical products is based on assessment by national governments of the risks and the benefits for use in their own country.”
“In some instances, Syngenta’s UK manufacturing facilities provide products no longer available or needed in a UK domestic context but deemed required for agronomic and agricultural reasons by farmers and regulators in the importing country,” added the spokesperson.
An article published by Pesticide Action Network Europe illustrates the irony: Food grown with EU-banned pesticides frequently finds its way back to European grocery stores. In 2022, 69 banned active substances were detected in food sold in the EU—especially in imported tea, coffee, and spices. In effect, Europeans are consuming pesticides that are banned from use on the farms of their home countries.
The regulation of herbicides like diquat varies widely across the globe, shaped not only by scientific evidence but also by political and economic forces. In regions such as the European Union and the United Kingdom, bans are often implemented when regulatory agencies determine that the health and environmental risks of a chemical outweigh its benefits—decisions typically informed by the precautionary principle.
In contrast, countries like the United States allow continued use of these herbicides based on older risk assessments or differing thresholds for acceptable exposure, especially under pressure from agrochemical industry lobbyists. “As a general rule… it is express U.S. policy to reject the precautionary principle in favor of so-called ‘risk-based’ regulation,” wrote Sharon Anglin Treat in a 2020 article for the Institute for Agriculture and Trade Policy, adding, “U.S. trade officials and multinational chemical and agri-food corporations often employ the language of ‘science’ to create a false choice to deny the potential for harm caused by lax U.S. regulation in the absence of the precautionary approach.”
In an article on their website, the Pesticide Action and Agroecology Network explains that corporations and trade associations frequently influence regulatory decisions by funding research, challenging proposed restrictions, and lobbying policymakers.
A particularly troubling consequence of this uneven landscape is the practice of “double standards” in pesticide exports. Trade agreements and intellectual-property protections further complicate efforts to align global policy, often prioritizing commercial interests over public health. Ultimately, this regulatory patchwork underscores the tension between the drive for agricultural productivity and the need to protect human and ecosystem health.
Growing recognition of the trade-offs inherent in current regulatory and agricultural systems is prompting a shift in how weed control is approached—one that prioritizes safety, sustainability, and long-term resilience over short-term chemical convenience.
Farmers and advocates are increasingly looking to safer and more sustainable practices as alternatives to diquat. Integrated Pest Management (IPM) principles and Integrated Weed Management (IWM)—which combine cultural, mechanical, biological, and limited chemical tools—are gaining ground as effective strategies to reduce herbicide reliance while maintaining yields. Mechanical methods, such as manual weed removal, tillage, flailing, or even hybrid electrical sprayer systems, have shown promise, especially for pre-harvest crop desiccation.
Regenerative and agroecological agriculture models—emphasizing organic matter recycling, cover crops, and microbial soil treatments—demonstrate that chemicals like diquat and paraquat can be phased out without resulting in yield penalties for some crops. However, significant barriers hinder broader adoption: Many farmers cite high costs, limited access to equipment, and a lack of training or institutional support. Still, some farmers remain optimistic about the shift. While they recognize the economic and agronomic challenges—such as temporary yield declines and higher input costs—they view the transition as a long-term investment in soil health, ecological resilience, and access to growing premium markets, rather than a step backward.
Despite these obstacles, grassroots resistance is growing. NGOs and health advocates—including the Environmental Justice Foundation and the Pesticide Action Network—have highlighted the exploitative trade of banned chemicals and campaigned for local and national restrictions on diquat use.
At the international level, scientists and health experts are calling for global phase‑outs and harmonized regulations. A proposal adopted at the 2023 International Conference on Chemicals Management (ICCM5) urged stakeholders to eliminate highly hazardous pesticides—including diquat—by 2030, and to prohibit or regulate exports of chemicals already banned nationally.
Together, these actions reflect a growing movement toward reducing chemical dependence, empowering farming communities, and promoting safer and more resilient agricultural systems that will benefit the consumer.
For consumers concerned about diquat exposure, primarily through household herbicides and aquatic weedkillers, there are several safer alternatives and practical steps to reduce risk.
A growing network of trusted resources offers practical, science-based, and health-conscious guidance, including Beyond Pesticides, which provides extensive tools for managing pests and weeds without synthetic chemicals and has a searchable database of safe alternatives and resources for creating pesticide-free lawns, gardens, and public spaces. Experts also recommend the homeowner-friendly primer on ecological, pesticide‑free landscaping published by the Northeast Organic Farming Association, which introduces the concept of organic land care—applying regenerative agricultural principles (biodiversity, soil health, water conservation, and low inputs) to everyday lawns and gardens.
Many mainstream weed-control products sold for home use—such as Spectracide Weed and Grass Killer or Reward—may contain diquat or similar toxic ingredients. Instead, consumers can opt for low-toxicity or organic alternatives such as vinegar-based, acetic acid herbicides, which are effective for small-scale spot treatment of weeds; clove oil and citric acid-based sprays; corn gluten meal, a pre-emergent herbicide that inhibits weed seeds from forming roots after germination; or using boiling water or flame weeders, which can be effective for patios, driveways, or between garden rows.
These alternatives are widely available at garden centers and online, often labeled “natural” or “pet-safe.” Look for OMRI-listed (Organic Materials Review Institute) products when in doubt.
By switching to non-toxic methods and staying aware of chemical ingredients in common weedkillers, consumers can not only help protect their health but also the health of ecosystems and workers further up the supply chain.
When it comes to food safety, choosing organic and regeneratively grown foods is one of the most effective ways to avoid crops treated with diquat and other synthetic herbicides, since USDA-certified organic standards prohibit their use. Supporting local farms that commit to chemical-free or low-input growing methods—particularly those using IWM or agroecology—also helps reduce herbicide dependence and build more resilient food systems, according to the USDA’s Conservation Practice Standards. It’s also wise to wash all fruits and vegetables thoroughly to help reduce trace chemical exposure.
Another good resource is the EWG Shopper’s Guide to Pesticides in Produce, an annual consumer guide published by the Environmental Working Group (EWG) that ranks conventionally grown fruits and vegetables based on the amount of pesticide residues found on them, using data from the U.S. Department of Agriculture (USDA).
Beyond personal choices, consumers can have a broader impact by advocating for local or state-level restrictions on the use of hazardous pesticides and urging elected officials to adopt the precautionary principle in public health policy. Finally, demanding action from the EPA to reassess outdated approvals can help close regulatory loopholes and protect both human and environmental health.
The issues surrounding diquat emphasize the urgent need for a global consensus on pesticide safety—one that prioritizes public health, ecological integrity, and long-term food security over short-term yield gains. Achieving that will require more than just regulatory reform. Transparency from chemical manufacturers, bold action from policymakers, and a groundswell of consumer awareness are the need of the hour. The path forward lies in investing in sustainable farming, empowering farmers with safer tools, and holding industry and governments accountable for the chemicals that shape our landscapes—and our lives.
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