A lifecycle risk assessment of nanopesticides

When you look at a glass of water, even if it's drawn from a river near farmland and looks clear, you should be aware that it could contain chemical residues from pesticides, molecules that may harm fish, insects, and even ripple up the food chain. For decades, this has been one of the biggest tradeoffs of modern agriculture: pesticides protect crops and boost food supply, but they often come at a heavy environmental cost.

A new wave of technology promises to change that story. Scientists are developing nanopesticides, pesticides wrapped in microscopic carriers designed to release their active ingredients more efficiently and in a targeted way. In theory, this means farmers can use less pesticide while keeping pests at bay, reducing the amount that drifts into waterways. But are these nano-formulations truly safer for the environment?

A recent study published in Environmental Science and Ecotechnology takes a hard look at this question. The research team carried out one of the first life cycle risk assessments of nanopesticides. Their test case was Imidacloprid, a widely used insecticide, compared with its nano-encapsulated cousin, nano-IMI.

The idea behind nanopesticides is simple. Instead of spraying pesticides in their raw chemical form, scientists enclose them in nano-sized capsules, think of them as microscopic delivery drones. These capsules protect the active ingredient from breaking down too quickly, help it stick where it’s needed, and release it more slowly over time.

For imidacloprid, which has been linked to declines in pollinators like bees and shows up in rivers worldwide, this approach could mean less pesticide in the wrong places. Farmers still get crop protection, but ecosystems get some relief.

Making these nano-capsules requires extra chemicals, energy, and processing steps. That’s why the research team didn’t just look at what happens after pesticides are sprayed, they examined the entire life cycle, from production to environmental breakdown.

The researchers used a combination of models to simulate how both regular imidacloprid (IMI) and nano-IMI behave. Specifically, they used Life Cycle Assessment (LCA) to obtain a big picture accounting of all environmental impacts from production, use, and disposal. Also, they used the USEtox model, a tool for estimating the toxicity of chemicals to freshwater ecosystems. And finally, they employed SimpleBox4Nano, a special model that predicts how nanoparticles move and transform in the environment.

Together, these methods allowed them to compare the toxicity of the chemicals and how rainfall, soil interactions, and particle behavior affect where they end up.

The results show a double-edged sword. Surprisingly, producing nano-IMI carries about four times the ecological risk of producing conventional imidacloprid. That’s because encapsulating pesticides requires extra solvents like methanol and energy-intensive processes like freeze-drying. On the other hand, once in the environment, nano-IMI looks much safer. In fact, after application, nano-IMI was two to five orders of magnitude less risky to freshwater ecosystems than IMI. In plain English, rivers and lakes downstream of farms see much lower exposure levels from the nano version. That’s because most of the nanoparticles stick to soil rather than washing into waterways.

One aspect to consider is that rainfall matters a lot. Under heavy rainfall, conventional imidacloprid floods into rivers, amplifying ecological risks. Nano-IMI, meanwhile, stays mostly locked in soil, making it far less likely to harm fish and aquatic insects. However, while freshwater ecosystems seem safer with nano-IMI, the study warns that more of the compound lingers in soils. That raises new questions: How do soil organisms respond to long-term exposure? Could residues accumulate in ways we don’t yet understand?

Agriculture is at a crossroads. The world needs more food, but traditional farming practices are straining ecosystems. Pesticides like imidacloprid are powerful tools, but their environmental side effects have fueled debates and bans in some regions. Nanotechnology offers a way forward, smarter pesticides that work harder but spill less into the environment. The global market for nanopesticides is booming. Valued at $735 million in 2024, it’s projected to more than double by 2032. Farmers and agribusinesses are excited about these new tools, and regulators are racing to catch up. The study makes one thing clear. We can’t just assume “nano” means better.

Yes, nanopesticides may reduce risks to rivers and lakes, but their production currently leaves a larger environmental footprint. The researchers suggest that applying green chemistry principles, for example, swapping out toxic solvents for safer alternatives or using plant-based nanocarriers, could make production cleaner and close that gap.

Instead of looking only at what happens “downstream,” the approach taken by the study considers everything from cradle to grave, a perspective urgently needed as we design the next generation of farming technologies. However, the data on nano-IMI reported in the study came from lab-scale production, not full industrial manufacturing. Real-world field data on nanopesticide drift and breakdown are still scarce. While freshwater risks seem lower, the long-term effects on soil organisms remain a question mark. Still, nano-formulations like nano-IMI hold real promise for reducing pesticide pollution in water. If production methods can be made greener, they may represent a win-win for farmers and ecosystems alike.

If you want to learn more, read the original article titled "A life cycle risk assessment of nanopesticides in freshwater" on Environmental Science and Ecotechnology at http://dx.doi.org/10.1016/j.ese.2025.100565.