Neonicotinoids – will the US follow Europe and ban bee-harming pesticides?
This year, the world’s relationship with controversial neonicotinoid pesticides will take a significant turn – with long-lasting consequences for science, industry, and the environment.
The US Environmental Protection Agency (EPA) is due to announce its decision on the future legality of the chemicals – the most widely-used class of insecticides in the US - which scientists say harm vital agricultural pollinators, including bees and birds.
Environmental campaigners want the EPA to follow the European Union (EU) in banning four of the most damaging neonicotinoids, but the current signs are that the US will instead opt for more restrictions on how the pesticides are employed – potentially extending their use for at least another 15 years.
Here, we examine in depth the global regulatory picture regarding neonicotinoid pesticides – with particular focus on the forthcoming EPA decision – and outline the main arguments for banning or restricting them.
The trouble with neonicotinoids
Neonicotinoids (also referred to as ‘NNIs’, ‘neonics’, or ‘NEOs’) are a family of insecticides including acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, nithiazine, thiacloprid and thiamethoxam. Chemically similar to nicotine, they are designed to control a variety of pests, especially sap-feeding insects, by attacking their central nervous systems.
According to the University of Maryland, there are several reasons why NNI-treated seeds are popular with farmers – including their low mammalian toxicity, effectiveness in controlling soil pests, and the fact that the seeds are often supplied pre-treated with fungicides at no extra cost. However, studies have linked increased use of NNIs and other pesticides with “serious harm to honey bee populations, declines in wild bee populations and harmful effects on a range of other species including many pollinators and other invertebrates and bird species.” Bees are essential for human food security because of their role in pollinating many of the world’s most important crops. According to the US Pesticide Action Network, they are “responsible for one in three bites of food” we eat, and for maintaining the agricultural economy as we know it. But in 2017, a wide-ranging study of 2,000 hectares of farmland in the UK, Germany and Hungary confirmed that NNIs “negatively affect pollinator health under realistic agricultural conditions” – including lowered survival rates and immune responses in bees, as well as reductions in reproduction and numbers surviving the winter.
What makes neonicotinoids so environmentally damaging?
Several other characteristics of NNIs also compound their impact on the environment, including their:
- status as systemic pesticides - meaning that unlike contact pesticides, which remain on the surface of treated areas, NNIs are taken up by the whole plant and transported through leaves, flowers, roots, stems, pollen and nectar.
- transmissibility – compared to foliar sprays, where about 50 per cent of the active ingredient is absorbed by the plant, at least 80 per cent of neonicotinoid seed treatments are absorbed into crop tissues and mostly end up in soils.
- persistence – according to field data used by EU regulators, the length of time that clothianidin and imidacloprid residues remain in the soil, as measured by their half-lives, puts them in the ‘very persistent’ category. The same figures also showed that they remained active for longer than chlorpyrifos, the organophosphate pesticide now banned in both the US and EU.
- high potential for leaching into water – according to the Pesticide Action Network, “clothianidin has a very high leaching potential, as measured by the Groundwater Ubiquity Score, while imidacloprid and thiamethoxam have high potential.” Aided by their high solubility in water, NNIs “readily move from application sites into waterways in and around fields, polluting puddles, ponds, wetlands, rivers, snowmelt, groundwater and wells.” One study cited by the US Center for Food Safety found high levels of imidacloprid near golf courses and plant nurseries in Maryland – highlighting the problem of contamination in run-off from turf grass and ornamental applications. This can have devastating effects on aquatic life - such as when run-off from one imidacloprid lawn application in Ohio killed 3,000 crayfish in a nearby stream – and on pollinators exposed to the pesticides as they collect water.
- non-target contamination – NNIs can contaminate a multitude of important organisms that are separate from the crops they are intended to protect. One study in Arkansas, Mississippi, and Tennessee detected neonicotinoid insecticides in 23 per cent of wildflower samples around recently planted fields of corn, cotton and soybean, with an average detection rate of about 10ng/g. The decline of certain bird populations has also been linked directly to the use of NNIs – with birds either dying after eating coated seeds, or from starvation due to diminishing numbers of the aquatic insects and other invertebrates they traditionally prey on.
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Restrict, or ban? The neonicotinoid dilemma now facing the EPA
The EU, which claims its pesticide laws are “the strictest in the world”, first moved to protect bees by restricting the use of three NNIs in member countries from 2013. After further scientific assessment, a full outdoor ban on imidacloprid, clothianidin and thiamethoxam followed in 2018 – while approval for the use of thiacloprid was withdrawn in 2020.
In the US, the EPA also insists it is “concerned about declines in pollinator health and… working to protect bees and other pollinators from pesticide risks.” In 2016 and 2017, it began a registration review for imidacloprid, clothianidin, thiamethoxam, dinotefuran and acetamiprid, while thiacloprid’s owner voluntarily cancelled its registration. In January 2020, the Trump-administration EPA issued “proposed interim decisions” on the use of the five pesticides, but stopped short of suggesting an EU-style ban. In the case of clothianidin and thiamethoxam, it said the “acute and chronic toxicity risks” to wildlife could be mitigated by measures including reducing application rates, crop stage restrictions to reduce impact on bees, cleaning up spills of treated seeds, and using buffers and vegetative filter strips in an attempt to stop spray drift and runoff. The proposed measures also included limited bans on the use of selected NNIs in certain areas – such as on residential turf and bulb vegetables.
The registration review process is due to conclude with a final decision in late 2022 – meaning that, if the proposed interim decisions are not overturned or strengthened, US farmers will be free to use NNIs on their crops for another 15 years. This prospect has been greeted with dismay by American environmentalists, with the Center for Biological Diversity describing the current EPA proposals as “token restrictions”.
“The EPA’s weak mitigation proposals are a far cry from what’s needed, ”said the centre’s environmental health director, Lori Ann Burd.
“The science is clear that neonics are simply too dangerous and must be banned if we’re going to save our pollinators.”
Under the Biden administration, the EPA has shown itself willing to make big calls on restricting America’s major environmental contaminants - such as PFAS water contamination and chlorpyrifos. But there’s no sign so far – on neonicotinoids at least – of the EPA moving on from recommendations arrived at during the previous presidency. An EPA spokeswoman told The Guardian as recently as last month that an outright ban was still unlikely, adding: “While the agency reviews the regulatory efforts of the EU, EPA also looks at regulation in countries such as Australia, Canada, Japan, New Zealand, and others that share our risk-based approach to regulation.”
“The differences in the details of our underlying laws can naturally lead to different regulatory conclusions.”
A permanent emergency? How neonicotinoids are still being used despite bans
Aside from the debate about whether the EPA will ban NNIs outright, the widespread practice of granting authorisations for the emergency use of neonicotinoids is also proving contentious on both sides of the Atlantic. The EU admits that, despite its ban on imidacloprid, thiamethoxam and clothianidin, and the non-renewal of approval of thiacloprid, “10 EU countries have repeatedly granted emergency authorisations for their use in sugar beets” under exemption powers granted to individual member states. According to EU rules, NNIs may be used “because of a danger which cannot be contained by other reasonable means” – but both France and Britain faced heavy criticism recently, when they activated the powers in response to aphid threats to their sugar beet industries. In the UK, a similar decision last year prompted 50,000 people to rapidly sign a petition demanding a U-turn. In the US, meanwhile, the EPA is currently considering allowing Florida farmers to spray clothianidin on 125,000 acres of citrus crops – for the ninth consecutive ‘emergency’ year.
Dr Ehrenstorfer: 45 years of heritage in pesticide reference materials
The growing public awareness of the highly toxic nature of NNIs, coupled with fast-evolving regulations around the world, demonstrates the continued need for laboratory testing, and therefore for reliable neonicotinoid reference materials.
Dr Ehrenstorfer has more than 45 years’ experience of producing pesticide RMs, allowing us to offer the most comprehensive portfolio of unique pesticide reference materials on the market. It features a range of 47 neonicotinoid products – including major NNIs such as clothianidin, thiamethoxam, and acetamiprid - for food and environment industry applications, as well as regulatory and quality testing.
Our technical expertise and capabilities allow us to innovate constantly - adding to our portfolio in response to evolving market needs and insights from working alongside leading pesticide manufacturers.
It also enables us to build custom solutions that precisely support our clients’ requirements – while our partnerships with TRC and Cambridge Isotope Laboratories (CIL) means we can also offer you a range of carbon-labelled compounds for the major NNIs, as well as deuterium-labelled analogues of acetamiprid, clothianidin, dinotefuran, thiacloprid and thiamethoxam. So, whether your interest in neonicotinoids is as a third-party testing laboratory, a researcher or a regulator/method developer, we have the right pesticide reference material for you. Feel free to browse our full pesticide range here. Or get in touch today to find out how we can assist you, whatever your laboratory’s needs.
Dr Ehrenstorfer’s work with NNIs and other pesticides also supports the United Nations Sustainable Development initiative – particularly its goals on zero hunger and responsible consumption and production – by promoting food security, sustainable agriculture practices and the responsible use of chemicals.
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