Riccardo Liguori Glyphosate is being replaced in U.S. weedkillers—but with diquat, a compound banned in Europe and linked to severe health and environmental risks.
@Canva
In the United States, glyphosate—once the king of herbicides and now infamous for its suspected links to cancer—is being quietly replaced. But not with something safer. According to a recent peer-reviewed study published in Frontiers and reported by The Guardian, a compound called diquat dibromide may pose an even greater threat to human health and the environment.
This shift marks what scientists call a regrettable substitution: replacing one harmful chemical with another that may be just as bad—or worse.
A dangerous replacement
While diquat dibromide has been banned in the European Union, the UK, China, and several other countries due to its acute and chronic toxicity, it continues to be widely used in the U.S.. Today, it’s one of the active ingredients in new formulations of Roundup—the weedkiller once dominated by glyphosate and now produced by Bayer, one of the largest pharmaceutical and agrochemical giants in the world.
Back in 2021, Bayer pledged to remove glyphosate from consumer-use Roundup products in the U.S., after facing over 170,000 lawsuits linking the chemical to non-Hodgkin’s lymphoma. But the replacement was far from a step forward.
“From a human health perspective, this chemical is significantly more dangerous than glyphosate,” said Nathan Donley, Environmental Health Science Director at the Center for Biological Diversity, speaking to The Guardian.
What the new research shows
The new study reviewed existing scientific literature on diquat and found that it severely disrupts the gut microbiome, compromising the intestinal barrier and altering the balance of beneficial bacteria. This disruption may allow toxins to leak into the bloodstream, triggering inflammation throughout the body.
But the effects don’t stop at the gut.
Diquat also targets critical organs—the kidneys, liver, and lungs. The study found that the herbicide:
- breaks down cell membranes in the kidneys, reducing their ability to filter waste;
- triggers liver inflammation by activating specific pro-inflammatory proteins;
- damages lung tissue, provoking a sustained immune response that may lead to tissue degradation.
In extreme cases, researchers warn, these effects could contribute to multi-organ dysfunction syndrome, a severe and potentially fatal condition.
200 times more toxic than glyphosate?
In 2024, environmental group Friends of the Earth analyzed product labels from Roundup bottles sold at major U.S. garden centers. Although these new formulas exclude glyphosate, they were found to be on average 45 times more toxic in terms of chronic exposure.
And diquat itself was up to 200 times more toxic than glyphosate in prolonged use scenarios.
Aside from its potential health hazards, diquat is also an environmental menace. It’s more persistent in soil and water, more toxic to bees, fish, worms, birds, and aquatic organisms, and more likely to contaminate groundwater than glyphosate ever was.
Mislabeling and misinformation
Despite these concerns, most U.S. consumers have no idea what they’re buying.
The packaging for the “new” Roundup is nearly identical to the older glyphosate-based version. While U.S. law does require disclosure of active ingredients, there’s no legal obligation to notify customers of changes in formulation—or that the new mix might be substantially more dangerous.
As a result, someone buying a bottle of weedkiller in 2025 could be unknowingly handling a product with a dramatically higher toxicity profile than what was on shelves just a few years ago.
No action from the EPA
Despite mounting evidence, the U.S. Environmental Protection Agency (EPA) has yet to launch a formal review of diquat.
Activists and scientists have repeatedly criticized the EPA for being overly influenced by the chemical industry, and for maintaining regulatory frameworks that are outdated and ineffective when it comes to banning substances—even in the face of clear scientific risks.
Diquat has been banned in Europe since 2019, but in the U.S., regulators are still focused on what Donley calls “legacy pesticides” like glyphosate, paraquat, and chlorpyrifos—all of which are already prohibited in most of the developed world.
“Other countries have banned diquat, but in the United States, we’re still fighting battles that Europe resolved twenty years ago,” Donley told The Guardian.
This regulatory lag could have far-reaching consequences—not just for human health, but for entire ecosystems.
