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The Toxic Truth About Neonic Coated Seeds

By Mary Wilson

The issue of coated seeds came to light recently when a severe contamination event was reported from an ethanol plant in Nebraska that was using coated corn seed for raw material. The seed corn, like the vast majority of seed corn in the U.S., had been coated with a pesticide, a neonicotinoid (neonic) that caused odors, strange illnesses in people, pets and wildlife, including near-by bee populations. The pollution had been spread through the company’s wastewater, as well as solid waste byproducts applied to the fields and sold to local farmers.

Pesticides used in seed coatings are not regulated by the federal government once the coating has been applied.

This scenario is likely not unique since neonic seed treatments are used on at least 160 million acres of U.S. crops (corn, soybeans, wheat and cotton) each year. This accounts for nearly half of all U.S. crop land and represents the largest single use of insecticides in the country. Seeds, in essence, become pesticide delivery devices, with no federal oversight once the seeds have been coated.

There are no federal requirements for safe handling, storage, disposal or even labeling. Farmers in most states do not know what is on their seed when they buy it and have no idea that any precautions should be taken.

Additionally, federal tracking of pesticide data is greatly underestimating harm to the environment since neonic treated seeds are not considered to be a pesticide application by the EPA and thus are not tracked.

Most of the pesticide in the coating becomes contamination of soil or water resources.

Despite the fact that these seed coatings are applied to control insects that may feed upon seedlings, it is surprising that much of that pesticide coating does not actually enter the crop itself. Depending on the crop, only about five percent of the active chemical enters the plant. The remaining 95 percent of the pesticide is left to pollute the environment through seed dust or soil contamination and water runoff. This situation creates multiple toxic routes which can affect bees and other wildlife through the contaminated plant, air pollution, and toxic run-off. Studies have shown harmful effects on bumblebees and other wild bees, butterflies, beneficial insects as well as freshwater dependent species.

Pesticide seed coatings generally do not increase crop yields.

Most U.S. studies and new studies from the E.U. show that yields for common crops do not increase with the use of neonic seed coatings. While there may be some benefit depending on crop, climate and insect species, such benefit is frequently offset by the fact that most of the pesticide does not get to the plant. Additionally there are issues of harm to beneficial insects and resistance to the pesticide over time. Many think that integrated pest management (IPM) methods are the best control of pests without the use of seed treatments. And yet nearly 100% of corn seeds are treated with neonics.

Not all seed coatings are pesticides.

It should be noted there are seed coatings other than neonics. Sometimes very small seeds are coated so that they are easier to handle. Some grass seeds are coated with a material that aids in moisture retention. And sometimes fungicides are used as seed coatings.

Kim Stoner of CAES says that “As far as I know, seeds treated with neonics are sold only to commercial growers, not to home gardeners. However, seeds treated with fungicides are sold to gardeners.” Fortunately, coated seeds have a brightly colored metallic look. It would be wise to handle any such seeds with caution. Unfortunately in many states coated seeds are not labeled, leaving the buyer unaware of any environmental or health concerns.

Connecticut provides guidance to farmers who use neonic coated seeds and requires labeling of such seeds.

The Connecticut Act Concerning Pollinator Health provides information and alternatives to farmers who use seeds coated with neonics, the aim being to reduce airborne dust associated with the planting process.

An Act Concerning Connecticut’s Seed Law requires adequate labeling of coated seeds with the chemical or generic name of the coating substance for all treated agricultural, vegetable and flower seeds. The provision requires a cautionary statement in the event that the seed is harmful to human or other vertebrate animals. Harm to invertebrates (bees, butterflies, and insects) and harm to the environment are NOT covered.

Even though Connecticut requires labeling, farmers may not know the names of neonics when they see the chemical or generic names on the label. Consumers should avoid seeds with the following chemical names: imadacloprid, clothianidin, acetamiprid, thiamethoxam and thiacloprid.

Even with some state regulations regarding use and labeling of such seeds, Kim Stoner comments that “There is very little regulation or even tracking of treated seeds once they are sold to the farmer. Thus, the lack of statistics, and thus the situation at the ethanol plant in Nebraska.”

CONCLUSION: Neonic-coated seeds are another example of indiscriminate poisoning of pollinators and ecosystems. As we learn more about the interconnectedness of natural systems, we realize that trying to fix one problem with yet another toxic pesticide may cause detrimental and sometimes far-reaching negative outcomes Whether you are a farmer, a small land owner, or a homeowner, managing the land using organic methods and concepts will help to reduce overload of chemicals to our landscapes.


Hoyle, Sarah and Black, Scott, Ethanol Plant Causes Severe Contamination in Nebraska, Xerces blog, January 2021

Stoner, Kimberly, February 8, 2021, email communication, CAES

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