Debate on the environmental impact of neonicotinoids and other pesticides

The production and use of synthetic pesticides has been increasing worldwide in recent years. Pesticides now protect around a third of all agricultural goods globally. The term pesticide covers a wide range of compounds including insecticides, fungicides, herbicides, rodenticides, molluscicides, nematicides, plant growth regulators and others.

Pesticides are highly regulated in the UK. The agricultural sector has argued that pesticides such as neonicotinoids can provide “the tools to effectively control crop pests in a way that is responsible, not just in terms of minimizing environmental impacts, but also in terms of being able to produce food and plants in a way that is safe, reliable and affordable for everyone”.

Environmental Concerns

Concerns about the environmental impacts of synthetic pesticides have been increasing in recent years. Studies have shown that usage of some pesticides, such as neonicotinoids, can have negative consequences for biodiversity and ecosystems. Residues of pesticides can end up in air, surface waters, groundwater, soil and biota, both after their intended and authorised use and following misuse or accidents.

The campaign group, Pesticides Action Network UK (PAN) cites extensive environmental impacts of pesticides, ranging from birds and animals being poisoned by residues on crops or starved by reductions in their food sources, to aquatic life being killed by reduced oxygen levels in water sources.

Various factors affect the impact of pesticides. The UN Environmental Programme (UNEP) has said that environmental risks will range from “very high to virtually absent” depending on factors such as pesticide use patterns, the toxicity of the pesticide, the conditions of exposure of non-target organisms, and the type of ecosystem exposed. Farming groups have emphasised environmental as well as economic benefits from pesticides, such as protecting the soil and cutting greenhouse gas emissions.

Neonicotinoids

A key concern is the impact of a class of pesticide called neonicotinoids on pollinators including bees. Neonicotinoids are active substances used in plant protection products to control harmful insects. They are a systemic pesticide which means they are taken up and transported throughout the plant – the flowers, leaves, roots, stems, pollens, and nectars. Their low toxicity towards mammals and humans has made them an important means of crop protection.  .

However, studies have suggested that exposure of bees at sub-lethal doses to neonicotinoids in pollen and nectar can have significant negative effects on bee health and bee colonies.

Neonicotinoids’ effects are not yet fully understood and differ between types of neonicotinoid. There are gaps in the evidence base and some of it is contested by manufacturers and farming groups but an increasing number of scientific studies indicate a range of harmful effects on pollinators. However, farmers have highlighted the environmental as well as economic benefits of neonicotinoids,

The use of most neonicotinoids was severely restricted in 2013 in the EU and UK due to their potential negative impact on bees and other pollinators. In 2018, the EU banned the outdoor uses of the three active substances imidacloprid, clothianidin and thiamethoxam, except for use in permanent greenhouses. The UK government supported this position.

Emergency neonicotinoid authorisation

By 2020, all but one neonicotinoid was no longer approved for use. However, emergency authorisations are allowed and the UK has granted them several times. The most recent was in January 2024 when the government authorised an emergency application in England of the use of the Cruiser SB pesticide, which contains thiamethoxam.

The government stated that this was necessary to tackle the threat to sugar beet crops from the yellows virus, carried by aphids, and the lack of alternative insecticide options. It said that the potential benefits of using the pesticide outweighed the risks to pollinators, particularly with the various limitations and controls attached to the authorisation.

The Labour Party has said neonicotinoids appear to have been “particularly  damaging to insect life”. Its policy is to set targets to reduce the use of these and other harmful pesticides and support sustainable farming methods such as integrated pest management with “less reliance on chemicals”. Labour’s then environment spokesman said that the government was wrong to issue an emergency authorisation in 2023.

The National Farmers’ Union has supported the use of emergency authorisations to protect a high value crop –In recent years the disease has caused sugar beet crop losses of up to 80%.

In contrast, environmental and wildlife organisations have been highly critical of the move, citing evidence of the potential environmental harm of neonicotinoid use.