Pesticides: of addictions, missing data and the importance of the EU

While the products that farmers use to protect their crops may seem inconspicuous, their effects on living beings are far from it. Despite being tested before coming to market, detrimental consequences for aquatic and terrestrial ecosystems, including human health, are often discovered only after these products have been in use for some time. Consequently, the authorisation of many pesticides has been withdrawn retrospectively. The most famous example is probably the insecticide DDT. In 1962, Rachel Carson’s book “Silent Spring” drew attention to the insecticide’s devastating effects on bird populations, specifically the thinning of their eggshells. Even today, pesticides are regularly taken off the market or their licenses are not renewed due to new studies on their effects or the development of better-targeted products. When a pesticide is banned, new generations of active ingredients follow, supposedly less harmful if applied in recommended quantities. Each substance must pass tests assessing its environmental impact. But how reliable are these tests? What roles do our governments, particularly the European Union’s (EU) regulations, play in this process?

But step by step. What am I even talking about here? Pesticides are products designed to combat unwanted life, be it herbicides harming herbs, insecticides impacting insects (mostly negatively) and fungicides fighting fungi. While some of them are used in forestry, urban maintenance, insect repellents or in households, the majority of pesticides is used for food production. Discussing pesticides also means discussing the way agriculture is done since they are essentially shadowing vast monocultures. In a diverse field, different cultures attract a more diverse web of life, so that the populations of different organism groups in the food web are kept more or less stable by predation. However, when only one or a few crops cover large areas of land, pests can spread easily. There are few predators and an almost unlimited food supply for organisms specialised in consuming that one crop (e.g., the corn borer). Consequently, pesticides often become the last resort to save the harvest. 

Yet, pesticides often overshoot their target. Life is interconnected in complex interacting communities of soil organisms, the so-called food web. When some target organisms are harmed, it often has cascading effects on many other non-target organisms. For example, for other organisms, the pesticide might kill the food source or their predators – in the latter case, they will likely multiply quickly and become the next challenge for the farmer. Also, life operates very similarly across organisms, leading to pesticides often effecting whole food webs. Various studies have found detrimental effects of pesticides on insects²,³ such as bees⁴, ⁵, but also birds⁶ and humans⁵, whereby the exposure to pesticides correlated with higher prevalence rates and risk of Alzheimer’s disease, Parkinson’s disease⁷, multiple sclerosis and suicide⁸.  The findings of a German insect study published in 2017, conducted in a Nature Protection Zone, revealed a decline of 75% in insect populations. This decline raises concerns when thinking of the many monoculture fields and how diversity must have been even lower there.

The trouble with pesticides is that they travel – they do not necessarily stay on fields where they were applied; they made it even to Antarctica⁹. While flying insects and birds are relatively mobile with better chances to migrate away from threats – this is less so when it comes to most soil life. Many soil organisms are minuscule, making them more susceptible to harm. Yet, our understanding of the impact of pesticides on soil biodiversity is progressing slowly. This is not only because we have little pesticide data but also deficient regulations.

Why does this matter? In this article, I want to elucidate the stakes, shed light on the flaws in the current pesticide assessment, and underscore the significance of our collective voice. EU elections are upcoming and environmental regulations are a crucial concern. But one step at a time. First of all, why does soil biodiversity matter? And how do pesticides affect the life in the soil?

The effects of pesticides on soil life and why soil life matters 

Soils are incredibly rich in life, holding up to 60% of Earth’s biodiversity¹⁰. Soil biodiversity is crucial for growing our food as it provides plants with needed nutrients, helps filter and store water, prevents erosion and floods, but also naturally controls pests. Pesticides can threaten soil life and harm the important roles it plays in keeping our ecosystems healthy. For example, they can disrupt the soil community, making it harder for the soil to perform important functions such as cycling nitrogen and carbon¹¹. This can even make plants more vulnerable to diseases by weakening their defences and helping pathogens become stronger. Also, one of the biggest health concerns – antibiotic resitance genes – might spread faster where pesticides are applied¹².

In various studies, researchers have uncovered the direct and indirect impacts of pesticides on soil organisms. For example, pesticides can accumulate in earthworms and smaller soil animals¹³. A big analysis of earthworm studies conducted across Europe, revealed that pesticides can disrupt earthworm crucial enzymes, growth and reproduction, thereby reducing their overall biomass¹⁴. Particularly concerning are the acute toxic effects observed when pesticides are combined with heavy metals¹⁵, such as copper commonly used in vineyards. Additionally, multiple pesticides, acting as cocktails, were found to be detrimental to soil fauna. Even when applied at recommended levels, the study found insecticides and broad-spectrum pesticides considerably harm soil animals¹⁶ .

However, so far, not many studies look at how pesticides affect the complex web of life in the soil, especially when multiple pesticides are used together or under field conditions. This is a big gap in our understanding, as the effects of pesticides can vary for different types of soil organisms. 

Together with my colleagues – from toxicologists to ecologists to soil scientists – we aimed to fill some of those gaps. Across Europe, we assessed how pesticides affect soil biodiversity in different ecosystems (not only in agriculture also in grasslands and woodlands) under different environmental conditions. This was an exploratory study, which means that instead of conducting experiments in greenhouse settings, we collected field data and analysed it in relation to its environment. We measured the soil life through DNA analysis and put this data in relation with detected pesticide residues. We will publish the paper soon and more details will follow here. 

What is currently awry: Gaps in European pesticide regulations 

However, all 230 in the EU-approved active pesticide substances (synthetic, for open-field use) are considered hazardous to humans and/or ecosystems at certain concentrations. Among them, 124 are even listed as top hazard substances¹⁸. Doubts have been raised about the effectiveness of the EU’s regulation and several studies have pointed to loopholes¹⁹. They found the authorisation process for the pesticide products to be flawed. The current testing protocol foresees the pesticide producers to assess the toxicity of their products. This is very problematic and a conflict of interest¹⁹. In this testing, only few organism groups are considered. Consequently, currently, the long-term effects of pesticides on various soil organisms are not assessed adequately. In addition, mixtures of pesticide products are not included in assessments of the products  despite that a lot of pesticides are used in mixtures or accumulate as such from year to year in the soil²¹. Another criticism was raised concerning the authorisation process and its tested ecosystems since currently only agricultural ecosystems are tested. This raises bias, because the pesticides applied might leach to surrounding ecosystems where they have very different effects on biodiversity. Also, currently, effects of pesticides in only few varying environmental conditions are tested. This is problematic because the effect of a pesticide strongly depends on soil (e.g. pH value) and climate (when applied before a rain shower the pesticides are more likely to leach in near-by environments).  

Apart from the authorisation process, further aspects of the pesticide product regulation were criticised such as the arbitrary setting of maximum residue levels for the marketed products.

Missing pesticide data

The European Food Safety Authority (EFSA) assesses pesticide residues in food, while member states monitor residues in drinking water. However, the monitoring practices and reporting of results are not standardised. Importantly, the impacts of pesticides extend beyond food and water, affecting major reservoirs such as soils and sediments. In soil, the fate of pesticides depends on various factors including their chemical properties, agricultural practices, and environmental conditions.  To assess pesticide’s effects on soils and other ecosystems, more data is needed to evaluate the impact of pesticides. However, to date, pesticide application in the EU is not being systematically recorded. As a result, crucial information such as dosage, timing, and location of application remains unavailable. 

The only data available are voluntary reporting and pesticide sales statistics. Many scientists have raised concerns about the overlooked environmental risks associated with pesticide application²². In the current situation, detrimental effects on ecosystems may only be discovered decades after their market approval, leading to delayed withdrawal. 

Farmers roles and perspectives

Farmers and farm workers are particularly exposed to pesticides and thus vulnerable to pesticide poisoning, especially when these chemicals are used inappropriately, such as without proper protective measures, in incorrect amounts or at the wrong times. However, many EU farmers cannot quit that easily on pesticides. They are stuck in vicious cycles growing monocultures that are managed by machines but in the same terms are dependent on mineral fertilisers and pesticides. This dependency is intertwined with the EU’s subsidy system for farmers, which coupes payments with the size of cultivated area, thereby favouring monocultures. Consequently, farmers are increasingly specialising on few crops only. The current system diminishes their ability to manage risks effectively, such as through crop rotations, intercropping and healthy soil management, which are crucial for keeping ecosystems thriving. This locks them in situations highly prone to pest attacks and extreme climatic events. Additionally, continuous pesticide usage weakens cultivated plants due to lost synergies since fewer soil organisms provide nutrients and resilience to pest attacks. Furthermore, herbicides eliminate plants that are a fodder source or also a habitat for many soil organisms. They also impact the symbiotic nutrient exchange between plants and microorganisms in the soil²³. 

Organic farming provides an alternative. Here, growing food relies on biodiversity and synergies between different life forms. In organic farming, synthetic pesticides and mineral fertilizers are not allowed. Farmers in organic production are healthier and also earn higher profits from their products. This is why the EU’s Green Deal aims to have a quarter of the EU’s farmers produce organically by providing more subsidies for organic farmers and those transitioning. These farmers need our support. Buying more organic, local produces but also discussing the differences between conventional and organic farming would benefit all life—from the aquatic (river and marine) ecosystems to the terrestrial ecosystems (including the farmers, consumers, birds, insects, soil organisms, etc.).   

Global entanglements around pesticides 

Imported products such as avocados bring a lot more with them then the water that they are taking away in places they are grown. This little excursus should give a glimpse into the complexity of our global food market. 

Import: Pesticides travel along global trade. Nearly 14% of the world’s goods imports are brought into the EU, often from countries with different pesticide regulations. Imported products, such as bananas and soy from South America, might carry residues of pesticides. While there are controls in place for imported products, the frequency and thoroughness of these checks vary. For instance, okras from India are only allowed if special ports confirm low pesticide concentrations. Similarly, 20% of American peanuts and 30% of Turkish cumin seeds undergo checks to ensure compliance.¹⁶   

In the European Food Safety Authority (EFSA) 2021 report, monitoring pesticide residues in food, they found Turkish grapefruits to have the highest exceedance rates, meaning their pesticide levels were above acceptable limits. The report also revealed that 44% of the tested samples contained one or more pesticides in quantifiable concentrations. The maximum pesticide residues found were a mixture of 39 different residues on raisins of unknown origin, 28 on bell peppers from Cambodia, and 19 on Turkish table grapes.²⁴ 

Export: The EU is the global leader exporting chemical products²⁵. Some of the pesticide products that are no longer allowed in the EU for usage are still produced and then exported. An example is DDT. Though banned in the EU due to its severe environmental impact, it is still used in Africa as an effective insecticide against malaria. However, even in Africa, DDT has far-reaching detrimental effects. Interestingly, the majority of pesticides in Africa are used on high-yield crops destined for export. This creates a situation where the EU manufactures banned products, which are then used to grow crops that are eventually reimported back into the EU. 

While it is important to better regulate and document the usage of pesticides in the EU, this could also outsource the production to non-EU-countries. We cannot justify outsourcing environmental burdens for importing cheap products produced at the cost of the environment in the producing country. In the EU, this would imply having the luxury to produce in environmentally friendly terms and leave the contaminated soil, air and water for others.   

The pandemic has warned us by opening our eyes for the importance of independent food markets. This is why more global solutions for pesticide regulations are needed but are far from being in reach. While the UN’s Food and Agriculture Organization (FAO) provides an International Code of Conduct on Pesticide Management²⁶ that should guide and inform governments, the pesticide industry but also the wide public, there is no international binding law able to control or foresee the compliance. 

European regulations matter

Environmental law in the EU has been found most successful if binding and applied at EU level. Previous binding environmental regulations have been successful when implemented at the EU level, such as the water framework (The Nitrate Directive) with its enforced compliance. It seems that regulating pesticides at EU level currently might be the best of all options. Despite national bans, producers of pesticide products can continue producing placing their products on markets outside that country. Also, pesticides do not stop at the border – all European Member States are in this together (maybe the islands a bit less though).  However, borders are also shared with non-EU countries, bringing further consequences as the invasion of Ukraine has shown. While the EU’s Green Deal foresaw an ambitious cut of pesticides used by 55% by 2030, this goal was withdrawn due to food security concerns (which seems a bit of an ironic justification in light of pesticides effects on (soil) life and the consequent degradation of soil’s fertility and resilience. 

For decades, the European Food Safety Authority (EFSA) has questioned the extraordinary approval of banned products by individual Member States¹².  They allowed farmers to continue using pesticides in exceptional cases during transitional periods following a ban; however, these exceptions were often used. For example, France granted a three-year exemption for the continued use of neonicotinoids on sugar beets beyond the ban. In 2023, however, the European Court of Justice prohibited such exemptions, underscoring the significance of the EU in this matter.

To reduce the amount of pesticides used, the EU is calling for integrated pest management, which means that pesticides should not be used preventively, but only in a targeted manner. While the approach is good, it does not automatically go hand in hand with solving the problem of monocultures and the lack of biodiversity in fields. Currently, there is no subsidy providing financial incentives for doing so. The EU parliament called for higher taxes on hazardous pesticides that could then be used as a subsidy for farmers applying integrated pest management²⁷. This suggestion follows the “Danish model”, already putting taxes on pesticides depending on their hazard-classification.

While in the last years, more emphasis was put on negative consequences of pesticides on non-target organisms (a study published by the European Food Safety Authority), those considerations have not been integrated yet into the legislation. More pressure seems to be needed.

What we can do: Lobbying for life (also the invisible one) 

The EU regulations named here are determined by lawmakers, with the EU Parliament playing a crucial role. From June 6-9, we have the opportunity to vote for our representatives. Environmental concerns and criticism of pesticides face strong opposition from the pesticide industry lobby in the EU. That’s why it’s crucial for EU citizens to represent the lobby for life in all its forms and colours, for farmers’ wellbeing, and for a liveable future for coming generations. Protecting life around us will, in the long term, protect us, our loved ones, and future generations, too. 

While there is still hope that the Green Deal is not lost yet, however, there is also an ongoing fear that the parliament will shift more to the right. These parties are known for putting environmental concerns on hold, such as by opposing the EU nature restoration law²⁸ and weakening the Green Deal²⁹. Let us prevent this and vote for a party that prioritises biodiversity and doesn’t sacrifice environmental promises and actions for short-term gains! 

The EU and its environmental regulations matter, a lot!!!  

Vote for biodiversity 😊  

References

1. Farmers turn to tech as bees struggle to pollinate (bbc.com) ↩︎
2. Hallmann, C. A. et al. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PloS one 12, e0185809 (2017).    ↩︎
3. Brühl, C. A. et al. Direct pesticide exposure of insects in nature conservation areas in Germany. Scientific Reports 11, 24144 (2021).   ↩︎
4. Rundlöf, M. et al. Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature 521, 77-80 (2015).  
   Henry, M. et al. A common pesticide decreases foraging success and survival in honey bees. Science 336, 348-350 (2012). ↩︎
5. Nicholson, C. C. et al. Pesticide use negatively affects bumble bees across European landscapes. Nature, 1-4 (2023).   ↩︎
6. Hallmann, C. A., Foppen, R. P., Van Turnhout, C. A., De Kroon, H. & Jongejans, E. Declines in insectivorous birds are associated with high neonicotinoid concentrations. nature 511, 341-343 (2014).  
   Rigal, S. et al. Farmland practices are driving bird population decline across Europe. Proceedings of the National Academy of Sciences 120, e2216573120 (2023). ↩︎
7. BROUWER, Maartje, et al. Environmental exposure to pesticides and the risk of Parkinson’s disease in the Netherlands. Environment international, 2017, vol. 107, p. 100-110. ↩︎
8. SABARWAL, Akash; KUMAR, Kunal; SINGH, Rana P. Hazardous effects of chemical pesticides on human health–Cancer and other associated disorders. Environmental toxicology and pharmacology, 2018, vol. 63, p. 103-114. ↩︎
9. POTAPOWICZ, Joanna, et al. Occurrences, sources, and transport of organochlorine pesticides in the aquatic environment of Antarctica. Science of the Total Environment, 2020, vol. 735, p. 139475. ↩︎
10. Anthony, M. A., Bender, S. F. & van der Heijden, M. G. Enumerating soil biodiversity. Proceedings of the National Academy of Sciences 120, e2304663120 (2023).   ↩︎
11. Sim, J. X., Doolette, C. L., Vasileiadis, S., Drigo, B., Wyrsch, E. R., Djordjevic, S. P., … & Lombi, E. (2022). Pesticide effects on nitrogen cycle related microbial functions and community composition. Science of the Total Environment, 807, 150734.
    Sim, J. X., Drigo, B., Doolette, C. L., Vasileiadis, S., Karpouzas, D. G., & Lombi, E. (2022). Impact of twenty pesticides on soil carbon microbial functions and community composition. Chemosphere, 307, 135820. ↩︎
12. QIU, Danyan, et al. Response of microbial antibiotic resistance to pesticides: An emerging health threat. Science of The Total Environment, 2022, vol. 850, p. 158057. ↩︎
13. Pelosi, Céline, Colette Bertrand, Gaëlle Daniele, M. Coeurdassier, Pierre Benoit, Sylvie Nélieu, Florent Lafay et al. “Residues of currently used pesticides in soils and earthworms: A silent threat?.” Agriculture, Ecosystems & Environment 305 (2021): 107167.
    Panico, S. C., van Gestel, C. A., Verweij, R. A., Rault, M., Bertrand, C., Barriga, C. A. M., … & Pelosi, C. (2022). Field mixtures of currently used pesticides in agricultural soil pose a risk to soil invertebrates. Environmental Pollution, 305, 119290. ↩︎
14. Pelosi, Céline, Colette Bertrand, Gaëlle Daniele, M. Coeurdassier, Pierre Benoit, Sylvie Nélieu, Florent Lafay et al. “Residues of currently used pesticides in soils and earthworms: A silent threat?.” Agriculture, Ecosystems & Environment 305 (2021): 107167. ↩︎
15. UWIZEYIMANA, Herman, et al. The eco-toxic effects of pesticide and heavy metal mixtures towards earthworms in soil. Environmental toxicology and pharmacology, 2017, vol. 55, p. 20-29. ↩︎
16. BEAUMELLE, Léa, et al. Pesticide effects on soil fauna communities—a meta‐analysis. Journal of Applied Ecology, 2023, vol. 60, no 7, p. 1239-1253. ↩︎
17. DONLEY, Nathan. The USA lags behind other agricultural nations in banning harmful pesticides. Environmental Health, 2019, vol. 18, p. 1-12. ↩︎
18. SILVA, Vera, et al. Pesticide residues with hazard classifications relevant to non-target species including humans are omnipresent in the environment and farmer residences. Environment international, 2023, vol. 181, p. 108280. ↩︎
19. STORCK, Veronika; KARPOUZAS, Dimitrios G.; MARTIN-LAURENT, Fabrice. Towards a better pesticide policy for the European Union. Science of the Total Environment, 2017, vol. 575, p. 1027-1033.
    Karpouzas, D. G., Vryzas, Z. & Martin-Laurent, F. Pesticide soil microbial toxicity: setting the scene for a new pesticide risk assessment for soil microorganisms (IUPAC Technical Report). Pure and Applied Chemistry 94, 1161-1194 (2022).   ↩︎
20. STORCK, Veronika; KARPOUZAS, Dimitrios G.; MARTIN-LAURENT, Fabrice. Towards a better pesticide policy for the European Union. Science of the Total Environment, 2017, vol. 575, p. 1027-1033.
    Karpouzas, D. G., Vryzas, Z. & Martin-Laurent, F. Pesticide soil microbial toxicity: setting the scene for a new pesticide risk assessment for soil microorganisms (IUPAC Technical Report). Pure and Applied Chemistry 94, 1161-1194 (2022).   ↩︎
21. STORCK, Veronika; KARPOUZAS, Dimitrios G.; MARTIN-LAURENT, Fabrice. Towards a better pesticide policy for the European Union. Science of the Total Environment, 2017, vol. 575, p. 1027-1033. ↩︎
22. FENNER, Kathrin, et al. Evaluating pesticide degradation in the environment: blind spots and emerging opportunities. science, 2013, vol. 341, no 6147, p. 752-758.
    STORCK, Veronika; KARPOUZAS, Dimitrios G.; MARTIN-LAURENT, Fabrice. Towards a better pesticide policy for the European Union. Science of the Total Environment, 2017, vol. 575, p. 1027-1033.
    SILVA, Vera, et al. Pesticide residues in European agricultural soils–A hidden reality unfolded. Science of the Total Environment, 2019, vol. 653, p. 1532-1545.
    BARAN, Nicole, et al. Pesticides and their metabolites in European groundwater: Comparing regulations and approaches to monitoring in France, Denmark, England and Switzerland. Science of the Total Environment, 2022, vol. 842, p. 156696.2
    BEKETOV, Mikhail A., et al. Pesticides reduce regional biodiversity of stream invertebrates. Proceedings of the National Academy of Sciences, 2013, vol. 110, no 27, p. 11039-11043.
    BRÜHL, Carsten A., et al. Terrestrial pesticide exposure of amphibians: an underestimated cause of global decline?. Scientific reports, 2013, vol. 3, no 1, p. 1135.
    WOOD, Thomas James; GOULSON, Dave. The environmental risks of neonicotinoid pesticides: a review of the evidence post 2013. Environmental Science and Pollution Research, 2017, vol. 24, p. 17285-17325. ↩︎
23. Fox, J. E., Gulledge, J., Engelhaupt, E., Burow, M. E., & McLachlan, J. A. (2007). Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants. Proceedings of the National Academy of Sciences, 104(24), 10282-10287.
    Chicago
    Ruuskanen, S. et al. Ecosystem consequences of herbicides: the role of microbiome. Trends in ecology & evolution 38, 35-43 (2023). ↩︎
24. EUROPEAN FOOD SAFETY AUTHORITY (EFSA), et al. The 2021 European Union report on pesticide residues in food. EFSA Journal, 2023, vol. 21, no 4, p. e07939. ↩︎
25. Production and international trade in chemicals – Statistics Explained (europa.eu) ↩︎
26. The International Code of Conduct on Pesticide Management | Pest and Pesticide Management | Food and Agriculture Organization of the United Nations | IPM and Pesticide Risk Reduction | Food and Agriculture Organization of the United Nations (fao.org) ↩︎
27. https://www.euractiv.com/section/agriculture-food/news/european-parliament-tax-pesticides-to-fund-integrated-pest-management/ ↩︎
28. Right wing takes yet another stab at killing EU nature law – POLITICO ↩︎
29. EU lawmakers debate the future of the Green Deal ahead of elections – Euractiv ↩︎