Small doesn’t mean safe: Why nanopesticides could be “boon or bane” for farmers

In our latest story, “Everything you need to know about nanopesticides” science journalist Virginia Gewin explores the revolutionary and potentially toxic world of nanoparticles. These molecule-sized, human-made substances already appear in a wide range of products from sunscreens to biomedical devices. But they are also are making their way onto farms in the form of nanopesticides, despite the fact that little is known about their impact on the environment or human health.

Gewin’s story tracks the research of Stacey Harper, one of a handful of scientists in the country studying the long-term health and environmental effects of nanoparticles. Based at Oregon State University in Corvallis, Harper has spent 10 years tenaciously analyzing their possible consequences to crops, consumers and the environment. The story of her quest for answers is online today with our media partner, Modern Farmer.

“An engineer as well as a toxicologist, Harper holds a unique perspective. She believes nanotechnology could help revolutionize farming just as it has medicine. But she sees the potential as well as the risks of nanopesticides,” writes Gewin. “By shrinking the size of individual nanopesticide droplets, there is broad consensus — from industry to academia to the Environmental Protection Agency — that the total amount of toxins sprayed on agricultural fields could be significantly reduced. Smaller droplets have a higher total surface area, which offers overall greater contact with crop pests. As well, these tiny particles can be engineered so that, for example, a physical shell called a capsule can better withstand degradation in the environment, offering longer-lasting protection than conventional pesticides. .”

And yet, the same traits that make nanoparticles so powerful also make them more unpredictable. Harper’s research looks at how nanopesticides may accumulate on crops or run off into bodies of water. She wants to know “whether they will be readily taken up by organisms that aren’t pests, and how long they will persist in the environment—properties that could radically change with size,” says Gewin.

Harper explains that “we just don’t know” what the fallout—if any—from nanoparticles will be, because so little funding has gone to find out. Over the last 13 years, the federal government has dedicated billions of dollars to the National Nanotechnology Initiative (NNI), which spans 20 departments and agencies and is tasked with encouraging the adoption of nanotechnology. While the NNI has allotted some funds for impact studies, the amount is still only a sliver of the total, and almost exclusively focused on workers who inhale nanoparticles.

Jennifer Sass, a senior scientist focused on regulation of toxic chemicals at the Natural Resources Defense Council, says, “There is very little environmental fate and transport testing of nanoparticles being done. It’s expensive research, and where companies may have collected some environmental monitoring data, they don’t have any interest in making that information public.”

Because nanopesticides are new formulations of existing chemicals, pesticide companies aren’t required to test them.  Nanosilver, the first nanopesticide to hit the market even appears in clothing and dietary supplements. And of the dozen pesticides evaluated by Harper and her team, 90% contained nano-sized particles. Yet, because they are based on already approved chemicals, they are essentially given a free pass. The regulatory thinking has been that size doesn’t change behavior.

Of course, that’s exactly what Harper says research has to prove, not assume. After testing hundreds of compounds, she says most are safe. But identifying the exceptions could be the difference between poisoning or protecting ourselves and the farmland we depend on. She’s developed an international database of the physical structures and toxicity of hundreds of compounds in the hopes that industry will pay attention.

The rush is on for companies to be the first to release new nano-technologies, like nano-sensors that will tell a farmer whether their soil has enough nitrogen. Harper remains hopeful that nanotechnology will ultimately make modern farming more sustainable. But with the advent of each new product, she is determined to keep pace, running the safety tests and asking the difficult questions that so few others are.

You can read the full story on Modern Farmer and here on our site. An accompanying infographic illustrates the basics of nanopesticides and the concerns they raise.