Colorado bill would curb uses of crop seeds coated with harmful pesticides
In a move that reflects mounting US opposition to a class of harmful insecticides linked to environmental and human health risks, Colorado lawmakers last week introduced a bill to curb the use of neonicotinoids.
The Strengthening Economic and Environmental Decisions (SEED) Act, or SB65, introduced to the state Senate on Jan. 28, would prohibit the use of crop seeds coated with neonicotinoids on farmland unless the buyer obtains a certificate from a government-approved verifier who can certify that the use of the treated seeds is “necessary and appropriate.”
If passed, the SEED Act would take effect Jan. 1, 2029, and would make Colorado the latest state to place restrictions on neonicotinoids, also called neonics. New York and Vermont, as well as the Canadian provinces of Ontario and Québec, already have similar restrictions in place that only allow the use of treated seeds when they are considered necessary to control pest problems.
Rather than spraying neonics on farm fields as farmers commonly apply other types of pesticides, neonics are commonly coated on seeds before they are planted. Such treated seeds are planted across over 150 million acres of US croplands each year, including corn, soybeans and wheat. Almost all of the tens of millions of corn seeds planted in Colorado each year are treated with neonics.
This type of prophylactic use – applied before levels of pest pressure are known – leads to overuse, critics say. The problem is compounded because unlike other types of pesticides, which generally remain where they are applied, neonics are considered systemic pesticides, which are taken up by the plant and move into the leaves, roots and stems, and also into the pollen and nectar.
Critics point to evidence that neonics persist in the soil and can migrate far from where they are applied, carried by rain and irrigation water, posing what some critics say is broad “risks to biodiversity and food webs.”
Scientists warn that the use of neonics poses a threat to important pollinators. A 2017 study found at least one neonic in 75% of honey samples tested from around the world, and research links the use of neonics to bee die-offs.
If used, neonics should be used sparingly and with caution, scientists caution. Outdoor uses of three neonics – imidacloprid, thiamethoxam and clothianidin – were banned in Europe in 2018.
A July 2025 report found neonics in Colorado surface water and groundwater at levels significantly above those expected to harm aquatic life over time, concluding that the contamination is mostly linked to crop seed treatments.
The Colorado bill is backed by a large coalition of the state’s farms, businesses and organizations. On Jan. 30, over 150 businesses, organizations and individuals from across the country sent a letter to the state’s House and Senate agricultural committees calling for lawmakers to protect their constituents from “harmful and unnecessary uses of systemic insecticides.”
Colorado’s Senate Agriculture & Natural Resources Committee is expected to take up the bill this month, according to Allison Johnson, a senior attorney with the Natural Resources Defense Council, one of the groups supporting the bill.
The measure “targets reductions that account for the vast majority of neonic pollution, while leaving flexibility for farmers to use what they actually need,” Johnson said. “Some environmentalists will say that it doesn’t go far enough. But if we can significantly reduce the largest source of neonic pollution in Colorado, that’s major progress.”
Brad Kuhn, owner of the Finding Nectar Nursery in Arvada, Colorado said the bill is “practical and science-based” and “does not ban neonicotinoids outright or take tools away from farmers.”
The Colorado Farm Bureau did not respond to request for comment.
Scientific evidence links neonics to health harms in wildlife and potentially in humans. While studies in humans are still limited, research ties exposure to the chemicals to liver cancer, osteoporosis, neurological symptoms and other issues. A 2022 study found neonics in the bodies of over 95% of pregnant women tested across the US, with further research finding that neonics can pass through the human placenta to the developing fetus.
A 2024 analysis of unpublished rodent studies submitted to the US Environmental Protection Agency (EPA) by neonic manufacturers found that the offspring of pregnant rats exposed to the chemicals were born with smaller brains and suggested a possible link between neonic exposure in the womb and attention-deficit hyperactivity disorder (ADHD). A 2025 study found that exposure to the neonic clothianidin damaged bees’ bodies in ways similar to cancer and aging.
The Colorado measure calls for fines of up to $50,000 per violation or suspended or revoked licenses for seed dealers who don’t comply.
Featured image by Getty Images on Unsplash+.
