The impacts of plant protection products on biodiversity and ecosystem services: findings from an INRAE-Ifremer collective scientific expert report

The use of plant protection products to protect yields and maintain green spaces and infrastructure can affect non-target organisms, in turn impacting the ecosystems and services they provide. Since the two previous collective scientific expert reports in 2005 and 2008¹, knowledge and diagnostic tools have evolved, as have the type of authorised substances and their uses. As a result, the French Ministries in charge of the Environment, Agriculture and Research commissioned INRAE and the French National Institute for Ocean Science (Ifremer) to conduct a new report on the impacts of plant protection products on continental (terrestrial and aquatic) and marine biodiversity, as well as on the ecosystem services² biodiversity provides. For two years, 46 experts affiliated with 19 different organisations studied more than 4,000 scientific references from the global body of literature. Their mission: to analyse the robustness of current knowledge on i) the state of environmental contamination by plant protection products (synthetic substances, biocontrol products) and their transformation products, and ii) their impacts on living organisms and the ecosystem services that depend on them. Their efforts also shed light on the regulatory evaluation techniques that determine whether a plant protection product can be placed on the market, on the methods used to monitor the effects of such products, and on the levers that could limit those effects. However, the report did not deal with farming practices or systems, particularly those that are liable to protect crops without the use of plant protection products. These topics are being studied in other projects, such as the collective scientific expert report on plant cover diversity to regulate pests and diseases (the results of which will be published in autumn 2022) and the “Growing and Protecting Crops Differently” research programme³. Moreover, this scientific expert report does not deal with the question of the impact of pesticides on human health, which was recently re-evaluated in the context of a collective expert report led by the French National Institute of Health and Medical Research (Inserm)⁴.

All environments are contaminated

Since the 2000s, public authorities have gradually stepped up their monitoring of the contamination of different environments from plant protection products. The list of substances has grown longer, and sampling, analysis and detection capabilities have improved, offering a more precise look at contamination in our environment today. The current state of knowledge shows widespread contamination of our ecosystems from plant protection products, with a peak in contamination in agricultural areas – in soil, streams and air – where most of these products are applied. This type of contamination is also found in areas at a distance from cultivated fields, such as aquatic environments and sediment, and as far as the deep sea and polar zones. Among the substances found hundreds or thousands of kilometres away from the area of application are many that have been banned for years, even decades, although in declining amounts. Exposure to plant protection products has been documented in a wide range of organisms and shows that contamination sometimes also spreads along food webs⁵.

Biodiversity is affected as well as the services it provides

In agricultural areas in mainland France, these products are involved in the decline of terrestrial invertebrate populations (such as pollinating insects and predatory beetles that feed on various crop pests), aquatic invertebrates and common birds. Numerous studies have identified direct acute effects, sometimes leading to the death of individuals, or the effects of chronic exposure, some of which can be transmitted between generations. Indirect effects have also been observed. They are mainly associated with the decline in food resources (insects and plants killed by plant protection products) and changes to or even the disappearance of habitats.

Plant protection products are an aggravating factor of ecosystem health, ranked fourth among direct factors threatening nature worldwide, on par with other types of pollution, and ahead of invasive alien species. Changes in land and sea use, resource exploitation, and climate change are the three leading factors with the greatest impact on biodiversity⁶. With regard to the sea, direct and indirect impacts have been found at the individual level (increased sensitivity of oysters or dolphins to viruses, disappearance of essential habitats for marine invertebrates, etc.) However, it is not clear from the literature whether these impacts extend to the population level and thus affect biodiversity.

When it comes to ecosystem services, few studies specifically deal with how such services are connected to the use of plant protection products, aside from those that have been linked to crop production, pollination and crop pest control. These studies show that while the use of plant protection products is effective in eliminating crop pests to maintain yields and thus food security, it negatively affects the two other services essential to production, namely pollination and the natural regulation of these same pests, ultimately threatening regulation.

The specific case of biocontrol

Insects, mites, bacteria, viruses, pheromones and other natural substances are increasingly used to protect crops. These promising alternatives to chemical products help regulate pest pressure without necessarily eradicating the pest. Generally speaking, scientific research has thus far focused mainly on evaluating the efficacy of biocontrol products, but gaps remain with regard to their impacts on biodiversity. While the expert report confirmed that most so-called biocontrol substances and organisms show low environmental persistence and ecotoxicity, there are exceptions. Some have a level of persistence or toxicity that is equal to or even exceeds their synthetic counterparts. Additionally, micro- and macroorganisms present specific risks because they can sometimes reproduce and spread throughout the environment.

Mitigating the impacts of plant protection products

The negative effects of plant protection products on the environment and on human health, as well as these products’ effectiveness in protecting crops, are evaluated according to a standardised European framework. European regulations on plant protection product marketing⁷and use are among the most stringent in the world, especially in terms of evaluating the effects of substances on the environment.

Many substances that are dangerous to human health, including several with detrimental effects on the environment, have been banned from the market. Examples include the herbicide Isoproturon (banned in 2016), the insecticides Chlorpyrifos and Dimethoate (banned in 2019), and the fungicide Mancozeb (banned in 2020).

However, EU regulations have their limits. They do not sufficiently take into account the complex effects on biodiversity and underestimate both the cocktail effect of substances that are mixed together and accumulate in the environment and their possible indirect effects. The system to monitor the impacts of plant protection products could also be improved by producing and collecting more data on biodiversity as part of phytopharmacovigilance⁸efforts and by expanding the number of species and studied environments.

The expert report also confirms that the application conditions for plant protection products as well as various landscape modifications (grass strips, hedgerows, etc.) help limit environmental contamination and its effects. The landscape is also a key element in preserving biodiversity habitats and refuge zones. The scientific literature emphasises that a combination of complementary actions on land are essential in preventing the products reaching the sea and mitigating their impacts, although they cannot entirely neutralise them. Finally, this collective scientific expert report identifies the need for knowledge on the impacts of plant protection products on marine biodiversity, in both mainland and overseas France. It also highlights the need for research on certain substances or biocontrol products, on their cocktail effects and the services they affect, and on certain organisms or biological compartments that require further study (amphibians, reptiles, microbiota, etc.) to better evaluate the future impacts of these products on the environment.