#herbicides

In October 2025, the WHO again sounded the alarm on the emergence of multidrug-resistant bacteria in hospitals around the world. Researchers have now found evidence that the use of weedkillers, in particular glyphosate, can drive the evolution of antimicrobial resistance in soil bacteria as a side-effect of developing resistance to the weedkiller itself. They hypothesized that resistant bacteria can be transmitted between hospitals and impacted soils in both directions through wastewater and other environmental pathways. Each year, antimicrobial resistance (AMR) is responsible for an estimated 1.1 to 1.4 million deaths worldwide. Now, scientists have found evidence that the spread of AMR isn’t always driven by bacteria evolving to resist the antibiotics themselves: rather, certain weedkillers can have the same effect. “Here we show that the most common species of multidrug-resistant bacteria from hospitals are not only resistant to multiple antibiotic classes, but also to high concentrations of the weedkiller glyphosate,” said Dr Daniela Centrón, a researcher at the Institute of Medical Microbiology and Parasitology in Buenos Aires and the senior author of the study in Frontiers in Microbiology. “These results suggest that weedkillers – which, unlike antibiotics, are widely applied in agricultural environments – may have the unintended side-effect of selecting for AMR among bacterial communities within the soil.”

Herbicides have been damaging nontarget vegetation since the compounds were first applied to row crops in the early 1940s. In the 1950s, the Forest Service linked boxelder blight in the Northern Great Plains to drift from crops sprayed with the widely used herbicide 2,4-D. In the 1960s, the herbicide damaged grapes in central Washington, and 2,4-D drift continues to damage grape vines, fruit trees, and vegetables today.   Herbicides and other agricultural chemicals can travel beyond the fields in many ways. A breeze can blow droplets away from sprayers or crop-dusting airplanes. Dust from fields has been found to contain pesticides. And many pesticides are volatile: In warm weather they turn into a gas and become part of the air. In the 1990s researchers found several herbicides in the rain falling on Isle Royale National Park, in Lake Superior, demonstrating that contaminants could be atmospherically transported “hundreds of kilometers and deposited by precipitation.”  The scale of herbicide damage is just one consequence of our ongoing battle with weeds. Herbicides became popular in the U.S. after World War II. Their use increased as farms grew in size and as farmers adopted conservation practices, like cover cropping and no-till farming, that reduce soil erosion. Instead of disking, plowing, and cultivating to control weeds, they simply sprayed chemicals. The amount of herbicides, pesticides, and fungicides used in the U.S. more than tripled between 1960 and 1981.

"An estimated six million tonnes of used coffee grounds are created annually. Most go to landfill, generating methane and CO2, or are incinerated for energy.

It’s an obvious waste of a byproduct still rich in compounds (if not flavour). On a domestic level, try directing your cafetiere contents to your garden, not your bin: used coffee grounds are excellent as an addition to home compost bins and wormeries, a mulch for roses and a deterrent to snails. And on a global scale, science might have the answer.

A new study in the Journal of Chemical Technology and Biotechnology suggests that used coffee could hold the key to a pressing environmental problem: agricultural contamination.

How could old coffee grounds solve agricultural pollution?

Scientists from Brazil’s Federal Technological University of Paraná found that leftover coffee can absorb bentazone, a herbicide frequently used in agriculture.

When old coffee grounds are activated with zinc chloride, their carbon content becomes 70 per cent more efficient in removing the herbicide.

The study’s tests involved bentazone dissolved in liquid and treated with activated carbon from used coffee grounds, to see how it affected onion root tissues called meristems. All plants grow from meristem tissue and a plant’s development is disrupted when its meristems are damaged.

If the test can be replicated on an industrial scale, it would be an environmental double whammy: diverting coffee waste from landfill and preventing damage to wildlife and nature from herbicides.

Why is bentazone a problem?

...The UK’s Environment Agency cites bentazone as having the potential to affect long-term water quality and lead to an increased need to treat the UK’s drinking water sources. The herbicide has been shown to impact human health if it is inhaled, ingested or absorbed through the skin.

While this is only preliminary research and more studies are needed to determine efficacy of activated coffee grounds on a global scale, it’s a promising start. The authors of the study say their results “suggest a circular economy solution for spent coffee grounds that are currently discarded without any recycling or reuse system”. We can all drink to that."

A historic legal agreement approved in federal district court yesterday afternoon commits the Environmental Protection Agency to a suite of proposed reforms to better protect endangered species from pesticides. The settlement, which covers more than 300 pesticide active ingredients, marks the culmination of the largest Endangered Species Act case ever filed against the EPA. Under the agreement’s terms, the EPA will develop strategies to reduce the harm to endangered species from broad groups of pesticides, including herbicides and insecticides, while taking further steps to target meaningful, on-the-ground protections to endangered species most vulnerable to harm from pesticides.

In Montana, noxious weeds have become a widespread problem due to ecosystem disturbances and degraded landscapes. Over time, the dominant method of managing these weeds has been the use of herbicides. But herbicides leave behind toxic residues—harmful both to us and to the planet.

Chia Thrane is taking a different approach. Through rotational grazing, her herd of goats naturally manages noxious weeds, restoring biodiversity, strengthening soil health, and proving that healing the land doesn’t have to come at the planet’s expense.

Women of the Earth, produced by Summer Moon Productions, featuring stories of women across America who are leading a new movement to restore and protect the land. By focusing on women in land stewardship roles, the series will explore women’s unique relationship to the earth and their innovative undertakings to heal the earth from climate change.

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