Common Weedkiller Ingredient Harms Gut Bacteria and Multiple Organs: Study

The toxic chemical diquat, an ingredient used in place of glyphosate in weedkillers in the United States, has been found to cause multiple types of damage to organs and kill gut bacteria, according to new research.

Diquat is sprayed extensively on orchards and vineyards, and its use has increased as controversial substances like paraquat and glyphosate are being relied on less frequently, reported The Guardian.

“Diquat is a widely used bipyridyl herbicide that is extensively applied in agricultural production and water management due to its high efficacy in weed control. However, its environmental persistence and the toxic effects it induces have raised widespread concern,” the authors of the analysis wrote. “Studies show that Diquat primarily enters the body through the digestive tract, leading to poisoning.”

Despite the new research suggesting diquat is even more toxic than glyphosate, the U.S. Environmental Protection Agency (EPA) has resisted banning the chemical, which is now being used in the common herbicide Roundup, The Guardian reported.

Due to its risks, diquat has been banned in the European Union, China, the United Kingdom and many other countries.

“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 Nathan Donley, the Center for Biological Diversity’s science director, as reported by The Guardian.

A Friends of the Earth analysis of EPA data in October found diquat to have roughly 200 times the toxicity of glyphosate when it comes to chronic exposure. The chemical is believed to be a carcinogenic neurotoxin with a potential link to Parkinson’s disease.

Bayer, the maker of Roundup, has faced almost 170,000 lawsuits by users of the product alleging it caused them harm. Bayer reformulated Roundup after glyphosate was classified as a possible carcinogen by the International Agency for Research on Cancer.

The new scientific review focuses on how diquat damages gut bacteria and organs.

‘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,” the authors wrote in the study.

Diquat reduces gut protein levels, which allows pathogens and toxins to enter the bloodstream through the stomach, triggering intestinal and bodily inflammation. Damage to the gut lining interferes with nutrient absorption and energy metabolism, according to the authors.

Diquat harms the lungs and liver and “causes irreversible structural and functional damage to the kidneys” by destroying their membranes and interfering with cell signals. 

Diquat-triggered inflammation also appears to attack the lungs and can lead to multiple organ dysfunction syndrome.

The authors of the analysis said more research on long-term exposure to low amounts of diquat is needed.

The EPA is not conducting a review of diquat, and the dangerous chemical has been largely ignored by nonprofits pushing for more stringent pesticide regulations.

Donley said that’s partially due to the weakness of pesticide regulations in the U.S., where diquat gets “overshadowed” by ingredients like paraquat, glyphosate and chlorpyrifos, which have been banned elsewhere and are currently the subject of legal battles.

“Other countries have banned diquat, but in the U.S. we’re still fighting the fights that Europe won 20 years ago,” Donley said, as The Guardian reported. “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.”