Is the Roundup Herbicide Diquat Toxic?

According to a new review of more than 100 studies suggests diquat, an herbicide now used in Roundup products, could cause direct damage the intestines and could trigger a toxic chain reaction in the rest of the body—possibly putting the liver, kidney, and lungs at risk.

As more research surfaces about the potential hazards of diquat exposure, including risks of neurological injury and other long-term health effects, the possibility of litigation is increasing. Farmers, groundskeepers, and homeowners may one day seek accountability from manufacturers if it is proven that companies failed to warn about the dangers of their products.

Health Risks Linked to Diquat Exposure: Is the New Roundup Formula Even More Toxic?

Diquat, which has replaced glyphosate in Bayer’s Roundup herbicides, is banned in the European Union. And maybe for good reason. The herbicide has been studied for years and has global restrictions due to potential toxic effects on the liver and kidneys. A published study in May 2025 in Frontiers in Pharmacology, now adds fuel to the fire, suggesting the chemical may harm the intestines as well. If you were wondering, yes, diquat is widely used in the United States, and in much of Latin America.

Studies conclude that diquat may weaken the intestinal barrier, kill off beneficial bacteria, interfere with nutrient absorption, and trigger chronic inflammation. This is particularly important because of how important gut health is to human health. Poor gut health can have serious repercussions throughout the body. Studies suggest that diquat’s harmful impact on the intestine can extend to other organs like the kidneys, lungs and liver. Many experts suggested there were risks before, and this adds to the case against the new Roundup formula safety profile.

In their report, the researchers wrote, “Studies show that Diquat primarily enters the body through the digestive tract, leading to poisoning. The core mechanism of its toxicity involves reactive oxygen species (ROS)-induced oxidative stress, which not only directly damages the intestinal barrier function but also exacerbates inflammation and systemic toxicity by disrupting the balance of the gut microbiota and the normal production of metabolic products.”

What Is Diquat?

Diquat (diquat dibromide) is a chemical herbicide used for plant desiccation, aquatic weed control, and general vegetation management. It works by producing reactive oxygen species in plants, which destroys cell membranes and quickly kills vegetation. Due to its effectiveness, diquat has been used around the world since the 1950s. Common brand names containing diquat include:

• Reglone

• Reward

• Diquash

Diquat is banned in the EU and the U.K. due to both environmental and potential human health risks. Popular herbicides like diquat, and its toxic cousin paraquat (also banned in the EU), can remain active in water and soil for up to 10 days, likely entering water sources and the food chain.

Diquat was ultimately banned because of the risks it poses to residents and passersby near the fields where it was sprayed, not mention those who actually work closely with the herbicides in the fields. Even if a farmworker is wearing personal protective equipment (PPE), European Food Safety Agency concluded in a report that worker exposure would exceed the maximum acceptable level by more than 4,000 percent.

Lessons From Roundup Litigation

The Roundup lawsuits offer a roadmap for how litigation around diquat could develop. In those cases, thousands of plaintiffs alleged that exposure to glyphosate caused cancer, and that Monsanto (later acquired by Bayer) knew of the risks but failed to warn consumers. Juries awarded significant damages, including punitive damages meant to punish corporate misconduct.

If future lawsuits establish a link between diquat exposure and neurological conditions like Parkinson’s disease, a similar wave of litigation could emerge. Key legal claims may include:

• Failure to Warn: Manufacturers may be held liable for failing to disclose known or foreseeable health risks.

• Product Liability: If diquat is shown to be unreasonably dangerous, companies could face strict liability claims.

• Negligence: Plaintiffs may argue that herbicide makers ignored or suppressed evidence of harm.

• Breach of Warranty: False assurances about the safety of diquat-containing products could support legal action.

Who Is Most at Risk?

Those most likely to suffer health effects from diquat exposure include:

• Agricultural workers applying diquat on large-scale farms.

• Groundskeepers, landscapers, and park employees.

• Homeowners using diquat-based products without proper protective equipment.

• Families living near farms, orchards, or waterways treated with diquat.

Diquat has long been marketed as a safe and effective weed killer, but evidence increasingly suggests that it may pose significant risks to human health. The history of Roundup litigation demonstrates how herbicide manufacturers can be held accountable when they fail to warn the public. As awareness grows about diquat’s hazards, lawsuits may become a powerful tool for victims to obtain justice and push for stricter regulation of toxic chemicals in agriculture.

FAQs About Diquat and Potential Lawsuits

• Is diquat banned in the United States? No. Diquat is still legal for agricultural and residential use in the U.S., though the EPA classifies it as a highly toxic substance. Some countries and regulators have restricted its use due to safety concerns, which could influence future U.S. policy.
• What health problems are linked to diquat exposure? Studies suggest diquat exposure may contribute to neurological disorders such as Parkinson’s disease, respiratory damage, kidney and liver toxicity, eye injuries, and skin burns. Severe cases of ingestion have been fatal.
• How does diquat compare to Roundup (glyphosate)? Roundup has been linked primarily to non-Hodgkin lymphoma, whereas diquat is more often associated with neurological and organ damage. Both herbicides raise legal questions about whether manufacturers adequately warned users of the risks.
• Who is most at risk from diquat? Farmworkers, groundskeepers, landscapers, and homeowners who handle diquat without protective equipment face the highest risk. Families living near areas where diquat is heavily applied may also experience secondary exposure.
• Can I file a lawsuit if I developed Parkinson’s after using diquat? If you can demonstrate long-term exposure to diquat and later developed Parkinson’s disease or similar neurological conditions, you may be eligible to file a product liability or toxic exposure lawsuit. An attorney can help connect your medical history with product use.
• What damages could I recover in a diquat lawsuit? Potential compensation may include medical expenses, lost wages, future care costs, pain and suffering, and in some cases, punitive damages designed to punish manufacturers if they concealed risks.
• Are diquat lawsuits happening now? While litigation is not yet as widespread as Roundup cases, awareness of diquat’s hazards is increasing. As more studies link exposure to chronic illness, lawsuits are expected to grow. Early claims may set the stage for future mass tort or class action litigation.

Joe Lyon and his team of toxic exposure lawyers are investigating cancers and other serious illnesses linked to occupational toxic exposure. We have filed numerous occupational cancer cases and settled many Roundup cancer claims on behalf of plaintiffs nationwide. Contact our attorneys for a free consultation and to seek compensation for the loss of health, loss of life, and financial damages.