Neonicotinoids
Neonicotinoids, often called neonics, are the most popular insecticides used in the United States. Hundreds of studies have shown they play a major role in population-level declines of bees, birds, butterflies, and freshwater invertebrates.
Neonics act on the nervous system. They are called systemic pesticides because they make all parts of a plant–including nectar and pollen–toxic to sensitive organisms, especially insects. They are very persistent in the soil, and easily build up because they degrade very slowly. Neonics are water-soluble, and are carried in drinking water, surface water and groundwater.
An estimated 75 percent of the corn and 33 percent of the soybean crops in the US are planted as neonicotinoid-covered seeds. The EPA has concluded that these treatments provide little to no benefits to soybean production. The plants take up only five percent of the insecticide coating; the rest is washed into the soil and water.
Acute and Chronic Effects on Water and Wildlife
The introduction of neonics is a huge ecosystem event which affects a considerable biomass. And the more we learn, the more dangerous these chemicals appear.
There are no Minnesota water quality standards for neonics. But the EPA has developed a measurement called Aquatic Life Benchmarks (ALBs) through testing of different organisms against different concentrations of chemicals. They have identified an acute and a chronic ALB for a few of the neonics. As new research has come in the EPA has lowered the ALBs for neonics.
The Minnesota Department of Agriculture has sampled several streams in Minnesota and found levels that sometimes exceed the ALBs. The Department has acknowledged that “focusing on acute exposures likely under-estimates the risks to aquatic life because it does not include long-term (chronic) exposure that may also occur in the waterbody”.
At low concentrations, neonic effects appear to be additive, and chronic effects increase over time. Here are some examples of effects on Minnesota wildlife:
- Honeybee foraging and learning may be impaired by imidacloprid at sub-lethal doses, which may cause colony collapse
- University of Minnesota researchers have studied neonicotinoids in surface- ground-and waste-water in different areas of Minnesota. They collected 167 samples at 65 sites. Ten percent of the samples exceeded the EPA chronic aquatic life benchmark.
- The Minnesota Department of Natural Resources released a preliminary report in 2021 which indicated that neonicotinoids had been identified in the spleens of deer all across Minnesota. While this study was not designed to identify the source of the neonicotinoids, the widespread nature of the results was surprising. Of the 800 deer spleens collected, 61 percent had neonicotinoid concentrations.
- In February 2020, Phillip Stepanian et. al. published an analysis of radar-detected mayfly emergence flights in the Upper Mississippi River and the Western Lake Erie Basin. In combination with water and sediment sampling, they found that in recent years (2012-2019) production of mayflies has declined by over 50 percent.
Human Impacts
According to the Centers for Disease Control and Prevention, about half the U.S. population is regularly exposed to at least one type of neonic; children ages three to five have the greatest exposures. Peer-reviewed research has linked exposure to neonics while in the womb to birth such as deformations of the heart and brain. Neonics are also linked to harms like muscle tremors, lower testosterone levels, altered insulin regulation, and changes to fat metabolism.
Regulation
Nationally and Internationally: Regulations are being implemented in many countries. Canada is working on tighter limits on clothianidin and the European Union has banned outdoor use of neonics. MDA has classified them as surface water pesticides of concern and the Minnesota Department of Health has guidance on their concentrations in groundwater. The EPA will complete a thorough review of neonics in 2024
In Minnesota: The Stewards are planning to push the MPCA for Minnesota water quality standards for neonics during its 2024 triennial review, which is yet not open for public comment. It is a complicated situation: MPCA produces and enforces water quality standards, but the Department of Agriculture is in charge of most pesticide regulations in the state.
Last session, two bills were considered in the state legislature: the Treated Seed Regulatory Program focused on systemic pesticides, and another bill would have restricted non-agricultural neonic use. Neither passed into law.
The Water and Wildlife Stewards are gearing up to support restrictions on the use of neonics in agriculture and non-agriculture settings, and will continue to push the MPCA to develop water quality standards for the two most common neonics.