Veterinary antimicrobials in Europe’s environment: a One Health perspective

Europe’s efforts to reduce antimicrobials used in food-producing animals

Antimicrobials are substances that kill or inhibit micro-organisms, including antibiotics, antivirals, antifungals and anti-protozoals. Due to their properties, antimicrobials are used to prevent or treat infections or infectious diseases in humans, companion animals and food-producing animals. However, their use can also have negative environmental impacts and potentially affect human or animal health. In particular, the use of antimicrobials in both humans and animals is considered one of the main drivers of the emergence and spread of antimicrobial resistance (Box 1).

In the European Union (EU), continued concern over high rates of AMR informed the inclusion of antimicrobials used in food-producing animals in the farm to fork strategy and the zero pollution action plan, which jointly set a target to reduce overall sales of antimicrobials for farmed animals and in aquaculture by 50% by 2030, compared with 2018 levels. Owing to their specific relevance to the EU zero pollution agenda, antimicrobials used in food-producing animals are thus the focus of this briefing.

Starting in the 1950s, increased veterinary use of antimicrobials enabled a progressive shift towards intensive farming and aquaculture practices in Europe’s food system (Kirchhelle, 2018). Antimicrobials began to be administered not just as a therapy but also as a preventive tool and, until 2006, to boost yields or for . This led to increasing efforts to regulate their use. Today, the EU regulatory framework applicable to antimicrobials used in food-producing animals comprises a wide range of policies and legislation (Figure 1).

Figure 1. Overview of the EU regulatory framework applicable to antimicrobials used in food-producing animals

A key role in this framework is played by Regulation (EU) 2019/6 on veterinary medicinal products (VMPs), which requires a benefit-risk assessment by a Member State or by the European Medicines Agency (EMA) before such products are placed on the market. The regulation also seeks to ensure prudent use of approved products, including by:

• reinforcing the EU-wide ban on the use of antimicrobials as growth promoters or to increase yields;
• banning the use of antimicrobials for mass preventive treatment (prophylactic) or to compensate for poor hygiene and management practices;
• imposing restrictions on the use of group treatments ahead of expected disease outbreaks (metaphylactic);
• providing stricter conditions for antimicrobial prescriptions; and
• designating antimicrobials that are reserved for treatment of infections on humans.

Upon request by the European Commission, the EMA prepares scientific and technical advice to inform further legal acts on the prudent use of antimicrobials and the collection of antimicrobial sales and use data.

Trends in the use of antimicrobials in food-producing animals in Europe

There is currently no publicly available Europe-wide information on the actual use of antimicrobials in food-producing animals. To obtain an indication of use patterns, sales data reported to the EMA and included in the European Surveillance of Veterinary Antimicrobial Consumption (ESVAC) database are normally used as a proxy indicator. According to the ESVAC data, total antimicrobial consumption for farmed animals and in in 31 European countries (European Economic Area countries, Switzerland and the UK) was estimated at 73.9 mg/PCU in 2022, corresponding to 4,458 tonnes of active substances. This represents a reduction of over 30% since 2017 (EMA, 2023). By comparison, total antimicrobial consumption in humans was estimated at 125.0 mg/kg in 28 European countries in 2021, remaining relatively stable since 2014 (ECDC et al., 2024). Overall, a greater volume of antimicrobials is still sold to treat disease in food-producing animals than for human medicine.

Sales of antimicrobials in the EU-27 decreased by 28.3% between 2018 and 2022, achieving more than half of the 2030 farm to fork target (Figure 2). This reduction can be explained by stewardship efforts undertaken at the EU and Member State level to reduce the use of antimicrobials in food-producing animals (e.g. prudent use guidelines, stricter provisions on prescription and preventive use) and/or the need itself for antimicrobials in animal husbandry (e.g. increased reliance on vaccinations, better diagnostics, measures to improve biosecurity and animal welfare).

Member States need to make further targeted efforts in order to reach the farm to fork target by 2030. The current positive trend could be supported by additional policy measures, as well as changes in food consumption patterns (e.g. preferences for organic meat production, shifts towards more plant-based diets). However, environmental drivers could become increasingly important and influence antimicrobial use patterns. For example, the risk of emerging zoonotic diseases linked to environmental degradation, as well as climate change-induced alterations in the distribution of disease vectors and parasites, could lead to the increased use of antimicrobials in animals (EFSA et al., 2020; FAO, 2020).

Despite efforts undertaken in Europe, the potential risks associated with the use of antimicrobials in food-producing animals should also be considered in the context of a globally interconnected food system. In particular, the growing global consumption of food of animal origin (OECD and FAO, 2023) may put pressure on farmers to adopt intensive production practices that require increased use of antimicrobials (Box 2).

Antimicrobials in the environment and risks to ecosystems

Many antimicrobials are only partially metabolised in the animal body. Depending on the type of compound and administration route, it is estimated that up to 90% of the active ingredient can be excreted (Sarmah et al., 2006). These residues can also reach soils and aquatic systems indirectly, for example when manure or sewage sludge is spread on agricultural land or when antimicrobials dispensed with animal feed in aquaculture are not eaten by the fish (Kemper, 2008). Once there, antimicrobial compounds disperse in the environment through a variety of processes (e.g. degradation, sorption to soils, leaching to water bodies) which depend on their properties and on environmental factors (Sarmah et al., 2006).

Importantly, use in food-producing animals is not the only source of antimicrobials entering the environment. Use in companion animals and in human medicine is a significant contributor. As veterinary and human medicines can contain the same antimicrobial substances, it is difficult to identify the specific source for the presence of residues in the environment. Furthermore, the manufacturing process of antimicrobials (Larsson, 2014), as well as their use to protect plant health (Miller et al., 2022), can also be sources of environmental pollution. A schematic representation of environmental transport routes for antimicrobials is shown in Figure 3.

Figure 3. Overview of environmental transport routes for antimicrobials from human and veterinary uses

In Europe, there is no overarching monitoring of antimicrobials in different environmental compartments. Systematic research on antimicrobial residues in aquaculture, manure, sewage sludge and the biota is also limited. As part of the monitoring conducted under the EU’s watch list mechanism since 2015, some pharmaceuticals have been widely reported in Europe’s surface waters (Marinov and Lettieri, 2020), with the findings recently used by the European Commission to propose the inclusion of three macrolide antibiotics among the priority substances list for surface waters. Unfortunately, based on the information submitted by EU Member States about their sampling sites, it is not always possible to determine the likely source of contamination (human or veterinary use). However, according to a database of scientific studies compiled by the German Environment Agency, concentrations of watch list pharmaceuticals above their limits of detection have been found in environmental matrices associated with veterinary uses across the EU (e.g. manure, livestock sewage, sediments and liquid emissions from aquaculture) (UBA, 2019).

The risks posed by antimicrobial veterinary medicines to non-target organisms and ecosystems are evaluated by the EMA and other regulators as part of the environmental risk assessment process that all veterinary medicines undergo prior to their authorisation. Nevertheless, the underlying knowledge base still presents . In addition to the lack of systematic monitoring data, there is also limited information on the ecotoxicology of many pharmaceuticals, their fate and behaviour in the environment, and possible mixture effects (EC, 2018). While observed impacts in Europe are still scarce, there is evidence that the emission of antimicrobials used in veterinary medicine to soils (e.g. through the application of manure) can alter soil microbial communities and affect their ecological functions (Jechalke et al., 2014; Grenni et al., 2018), for example their role in biogeochemical cycling processes (Roose-Amsaleg and Laverman, 2016). In addition, ecotoxicity tests have shown that some antimicrobial compounds and their transformation products could potentially pose risks to aquatic organisms (Löffler et al., 2023; Isidori et al., 2005).

Antimicrobials in food-producing animals: what are the links with animal and human health?

Prudent use of antimicrobials helps protect the health and welfare of food-producing animals, thus contributing to food safety and preventing the spread of zoonotic diseases. However, in the absence of adequate risk management measures, humans may be potentially exposed to residues of antimicrobials and other pharmacologically active substances used in VMPs through the consumption of food and drinking water that has been contaminated. This could present risks to health. For example, antimicrobial residues may interfere with the human gut microbiome, disrupting the immune system or leading to metabolic disorders, intestinal disorders and neurological alterations (FAO, 2023).

To manage this risk, the European Commission establishes maximum residue limits  for antimicrobials and other pharmacologically active substances used in VMPs. MRLs are based on a scientific assessment by the EMA. In addition, appropriate withdrawal periods are set for veterinary medicines containing antimicrobials as part of their marketing authorisation procedure. Both MRLs and withdrawal periods are calculated to ensure that consumer exposure to residues in food will remain at levels that do not represent a risk to health.

According to the latest monitoring data reported to the European Food Safety Authority (EFSA), exceedances of MRLs in animals and animal food products are generally very rare in Europe. In 2022, only 0.14% of analysed samples were found to be non-compliant for antibacterials in EU Member States, Iceland, Norway and the UK, in line with the results of the previous 13 years (EFSA et al., 2024). There is no such monitoring for drinking water in the EU, and the scientific literature is also limited to ad hoc surveys, although reported concentrations have so far been considered unlikely to pose risks (EC, 2018; Lettieri et al., 2018).

The most direct health risk associated with the use of antimicrobials in both animals and humans is represented by the emergence and spread of AMR. In Europe, among Salmonella and Campylobacter bacteria to critically important antimicrobials for human medicine remains low, with some exceptions. At the same time, resistance of these bacteria to commonly used antimicrobials is observed frequently in both animals and humans in many EEA countries (EFSA and ECDC, 2024). Overall, more than 800,000 human infections and approximately 35,000 deaths are estimated to occur in EEA countries every year due to bacteria resistant to antibiotics (ECDC, 2022). The European Centre for Disease Prevention and Control (ECDC) estimates that healthcare-associated infections may currently amount to nearly 71% of all resistant infections.

More data are needed to investigate the contribution of antimicrobial use in food-producing animals to human infections with resistant bacteria. Nevertheless, the JIACRA reports jointly published by the ECDC, EFSA and EMA have repeatedly found a significant association between the veterinary use of certain groups of antimicrobials and the occurrence of resistance to those antimicrobials (including some considered critically important for humans) in certain bacteria from food-producing animals (ECDC et al., 2024). The fourth JIACRA report, in particular, found that in some cases the AMR in bacteria from humans was correlated with the presence of AMR from food-producing animals (ECDC et al., 2024). This suggests that veterinary use of antimicrobials may play a role in the emergence of certain resistant infections in humans, particularly those of food-borne origin. At the same time, it is important to note that progress has been made in reducing AMR in food-producing animals in several EU Member States (EFSA and ECDC, 2024). Member States that have reduced their consumption of antibiotics in both animals and humans have seen a decrease in resistant Escherichia coli bacteria (ECDC et al., 2024), showing that measures to reduce use can help tackle AMR.

Antimicrobials, AMR and the role of the environment

Despite a growing knowledge base on the relationship between AMR and antimicrobial use in humans and animals, there are still significant knowledge gaps regarding the role played by antimicrobials in the emergence and spread of AMR via the environment. Once antimicrobial residues are excreted from treated animals or otherwise reach the environment, they can remain stable for weeks or even months and exert a selective pressure on bacterial populations in soils or water, including at very low concentrations (Bengtsson-Palme et al., 2018; CVMP, 2021). Treatment processes can significantly reduce the levels of resistant bacteria and genes in wastewater and manure before these are discharged in the environment or re-applied on land. However, some will inevitably remain and their prevalence may even increase (Manaia et al., 2018; He et al., 2020), resulting in increases in the occurrence of AMR (Bengtsson-Palme et al., 2018). Furthermore, other substances used in agricultural settings, such as biocides or heavy metals used as feed supplements (e.g. copper and zinc), have also been shown to exert selective pressure towards bacteria resistant to antibiotics through a mechanism known as co-selection (Lettieri et al., 2018).

It is difficult to estimate the risk that the environmental reservoir of resistant bacteria and AMR genes may pose to animal or human health — and even harder to quantify the relative contribution of antimicrobial use in food-producing animals. However, it is increasingly acknowledged that environmental compartments such as water (e.g. surface waters, sediments, wastewater), soils, air and wildlife may enable the further spread of resistant bacteria and genes (CVMP, 2021; UNEP, 2023). In particular, the simultaneous presence in such compartments of different bacterial strains or species, some of which have acquired resistance to antimicrobials, could lead to the horizontal transmission of AMR genes to clinically relevant bacteria (Munita and Arias, 2016).

While the evidence base on the transfer of resistant bacteria and AMR genes from the environment back to humans is still evolving, studies have demonstrated the potential presence of resistant bacteria in vegetables and fruits, meat and aquaculture products, and contaminated drinking and recreational waters (CVMP, 2021). A risk thus exists that resistant pathogens are transferred from the environment or food products to humans, or that AMR genes are transferred from environmental bacteria to bacteria that cause infections in humans. Further research, including under relevant Horizon Europe partnerships, is needed to fill these critical knowledge gaps and help assess and quantify such risk.

Reducing antimicrobial pollution from food-producing animals: a One Health approach

The complex ways in which the use of antimicrobials influences human, animal and ecosystem health highlight the value of a One Health approach to assessing their impacts and reducing potential risks. The One Health approach, which recognises that the health of humans, animals, plants and the wider environment are linked and interdependent, emphasises the need for transdisciplinary and multi-sectoral collaboration in science, policy and society (OHHLEP et al., 2022). However, while the environment is a key component of One Health, its contribution to the emergence and spread of animal-mediated diseases has traditionally received less attention in research and disease surveillance systems (WHO, 2022). This means that environmental aspects should be included more prominently in efforts to prevent, predict, detect and respond to risks to health.

In the context of antimicrobials used in food-producing animals (but the same considerations should be applied to all uses of antimicrobials),  knowledge about the role the environment plays as a reservoir of antimicrobial residues, resistant pathogens and AMR genes should be expanded (CVMP, 2021; Lettieri et al., 2018). Not only would this support the environmental risk assessment of antimicrobial veterinary medicines, but it would also strengthen surveillance and early warning systems, as highlighted by the 2023 European Council recommendation on stepping up actions to combat AMR. From this perspective, the improved monitoring framework foreseen under the proposed revision of the EU’s water legislation could further support the EU and Member States in measuring the effectiveness of actions to reduce the use of antimicrobials, identifying pollution hotspots and better assessing the potential impacts on humans, animals and the environment.

At the same time, applying a comprehensive One Health approach entails acting to mitigate risks at source (Markotter et al., 2023), including by preventing the release of antimicrobial residues into the environment in line with the zero pollution hierarchy (EEA, 2022b). Actions to reduce the use of antimicrobials in food-producing animals, as well as the need to use them in the first place, have already led to demonstrable effects in Europe while safeguarding animal health. By comparison, downstream interventions such as improving wastewater treatment are important, but even the most advanced technologies currently available do not result in complete removal of antimicrobial residues from the environment (OECD, 2019).

In addition to the measures introduced at the EU level by Regulation (EU) 2019/6, the 2023-2027 common agricultural policy (CAP) offers Member States the opportunity of using their CAP strategic plans to fund interventions aimed at reducing the veterinary use of antimicrobials. For this period, around 20% of livestock units in the EU-27 will be impacted by such measures, which may be additional to other actions funded at the EU or national level (Figure 4). Other actions supported under the CAP, such as measures to improve animal welfare and promote organic farming, may also contribute to achieving the farm to fork target.

EU Member States can adopt a wide range of strategies to reduce antimicrobial use in food-producing animals. According to the RONAFA joint scientific opinion published by the EMA and EFSA, specific measures already implemented by some Member States appear to have reduced veterinary antimicrobial use. These include the adoption of national reduction targets, requirements to conduct farm-level measurements and benchmarking of antimicrobial use, stronger controls on mass antimicrobial treatment and restrictions on the use of critically important antimicrobials (CMVP and BIOHAZ et al., 2017). There are also a variety of measures that Member States can introduce to reduce the need for antimicrobials in the first place, while still ensuring health and welfare. This includes:

• external biosecurity measures to prevent the introduction and spread of pathogens between farms;
• internal biosecurity measures to be adopted within a farm;
• tertiary prevention measures (e.g. vaccinations, genetic selection, measures to improve animal welfare);
• alternative measures (e.g. probiotics and prebiotics, bacteriophages, organic acids);
• promotion of farming systems that require low antimicrobial use, such as organic production.

In general, all options to reduce the use of antimicrobials in food-producing animals have been found to have advantages and disadvantages, highlighting the importance of integrated approaches that are adapted to local circumstances (CMVP and BIOHAZ et al., 2017; OECD, 2023) (Box 3).

When considering broader global trends in the use of antimicrobials in food-producing animals (Box 2), EU requirements on residues of pharmacologically active substances in imported food products help to protect food safety. For example, these requirements ensure that only third countries with approved residue control plans are able to export to the EU. Recently, the EU also required Member States to expand monitoring of AMR in meat products sampled at border control posts. In addition, certain measures introduced by Regulation (EU) 2019/6 (e.g. the ban on antimicrobial use for growth promotion) apply to economic operators in third countries exporting animals or animal food products to the EU. However, this is not sufficient to confront some of the planetary-level impacts associated with antimicrobial use in food-producing animals, most notably pollution caused by antimicrobial residues and the emergence and spread of AMR (UNEP, 2023).

On the one hand, this means that EU institutions should continue to promote ambitious action within multilateral bodies that have a normative mandate on the use of antimicrobials in food-producing animals, such as the Codex Alimentarius, the World Organisation for Animal Health and the other institutions of the . This is in line with the actions proposed in the EU One Health action plan against AMR and the strategic approach to pharmaceuticals in the environment.

On the other hand, it also suggests that reduced antimicrobial use in food-producing animals should be seen as part of a more fundamental rethinking of current food production and consumption systems to make them more sustainable (EEA, 2022a, 2019). Such a rethink could include exploring alternative farming practices and phasing out systems that are intrinsically reliant on heavy inputs of antimicrobials (CMVP and BIOHAZ et al., 2017), as well as supporting consumption-side measures to reduce demand for animal protein and promote healthier diets (Van Boeckel et al., 2017; Willett et al., 2019).

Additional information

• Zero pollution monitoring assessment
• Rethinking agriculture
• The European environment — state and outlook