farmer in a tractor applying a spray herbicide or pesticide to a row of agricultural crops

Weedkiller Ingredient Widely Used in US Can Damage Organs and Gut Bacteria, Research Shows

July 06, 2025 | Source: The Guardian | by Tom Perkins

The herbicide ingredient used to replace glyphosate in Roundup and other weedkiller products can kill gut bacteria and damage organs in multiple ways, new research shows.

The ingredient, diquat, is widely employed in the US as a weedkiller in vineyards and orchards, and is increasingly sprayed elsewhere as the use of controversial herbicide substances such as glyphosate and paraquat drops in the US.

But the new piece of data suggests diquat is more toxic than glyphosate, and the substance is banned over its risks in the UK, EU, China and many other countries. Still, the EPA has resisted calls for a ban, and Roundup formulas with the ingredient hit the shelves last year.

“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, science director with the Center For Biological Diversity, which advocates for stricter pesticide regulations but was not involved in the new research. “Regrettable substitution” is a scientific term used to describe the replacement of a toxic substance in a consumer product with an ingredient that is also toxic.