Academic Advisory Panel – chemicals in the environment: minimising negative impacts of pesticides and veterinary medicines - advisory note

Introduction

Pesticides and Veterinary medicines play an essential role in agriculture and animal health, but they can also pose significant environmental risks affecting soil, water, air, biodiversity, and human health. Pesticides, and veterinary medicines including insecticides, herbicides, fungicides, antiparasitics and antibiotics can harm non-target organisms, such as pollinators, and birds. Runoff from agricultural fields can carry these chemicals into rivers, lakes, and wetlands affecting aquatic life. Overuse of veterinary medicines, particularly antibiotics, contributes to antimicrobial resistance (AMR), impacting both animals and humans. For these reasons it is important that minimising the negative impacts of pesticides and veterinary medicines is considered in future agricultural policy.

Sustainable practices, such as Integrated Pest Management (IPM) and responsible veterinary medicine use, are essential for mitigating environmental risks. However, gaps remain in data collection on pesticides and veterinary medicine use. Current pesticide usage data is derived from surveys of a sample of holdings, meaning the figures are estimates rather than exact totals. Similarly, data on veterinary antibiotic use is based on product sales, which does not account for wastage and cannot be interpreted as precise usage figure. There is also limited understanding of the full, long-term environmental impacts of these chemicals. Furthermore, the effects of pesticides and veterinary medicines on treatment effectiveness and the environment, particularly under changing climate conditions, remain uncertain.

This advisory note, prepared by the Academic Advisory Panel (AAP), provide insights for implmenting sustainable pest and parasite control solutions while minimising the unintended environmental impact of pesticides and veterinary medicines within the Agricultural Reform Programme. This note summarises discussion from the AAP meeting held on the 28 October 2024. The discussion focussed on practices to support sustainable pest contrl, indicators that could be used to monitor the adverse effect of chemicals on the environment, and how risks from pesticides and veterinary medicines may change under future climate conditions.

Key summary of the discussion

The Panel identifies several best practices to support the sustainable use of pesticides and veterinary medicines, and reduce their negative impact. Prioritising biosecurity practices in routine farm operations helps prevent pest, disease and weed spread. Targeted Selective Treatment (TST) in animal care - treating only animals that need it or will benefit from treatment - minimises unnecessary veterinary drug use and reduces selection for resistance to treatment. In crops, Integrated Pest Management (IPM) can reduce pesticide reliance by assessing risk and applying chemicals only when and where necessary, thereby limiting environmental contamination. AAP recommends demonstrating the economic benefits of TST and IPM through case studies in both livestock and crops, providing guidance on sustainable practices, and promoting peer learning and collaboration with advisors to drive broader adoption of best practice.

AAP notes that comprehensive data collection and statistical modelling are essential to monitor the impact of pesticides and veterinary medicines’ impact on biodiversity and the environment. Models help detect trends and quantify pollution effects or unintended environmental impacts on ecosystems and their inter-related constituent components. Monitoring should include a range of species, including non-target organisms, and cover various ecosystem components such as soil, water, and multiple species, as declines in one species can impact others in the food chain. Data analysis should also consider factors such as climate, weather, management, and land-use changes that may influence the population health of non-target species.

AAP notes that climate change may amplify the risks associated with pesticides and veterinary medicines due to a range of factors. It is highly likely that changes in the amount and types of treatments applied will be needed, impacting the resilience and response of ecosystem biological components. For example, increased rainfall could lead to greater pesticide runoff, while shifting weather patterns and raising temperatures may complicate the timing of application. Additionally, warmer, and more humid conditions may encourage the spread of domestic and non-native pests and pathogens, increasing the demand for pesticides and livestock treatments. However, innovative solutions such as highly selective control options, including RNA-based or biocontrol treatments, offer potential solutions by precisely targeting pests, reducing the need for broad-spectrum treatments and minimising unintended harm to non-target species.

Key discussion points:

1. Practices that could help to support sustainable pest control solutions and minimise the impact of chemicals on the environment and biodiversity.

• biosecurity should be the top priority as a routine preventative approach on livestock, mixed, and arable farms. Implementing management practices that collectively reduce the risk of introducing and spreading of disease-causing organisms, pests, and weeds onto and between farms is crucial and can be vital for business sustainability. Strengthening biosecurity measures is a key step towards prevention. The Panel recommends that consideration should be given to mandating biosecurity measures through appropriate policy mechanisms
• targeted Selective Treatment (TST) of animals - treating only those animals that would benefit most from medical intervention - should be promoted as the gold standard for animal health practice where evidence for efficacy of this approach exists e.g. anthelmintics use in livestock. Testing along with evidence-based treatment decisions are preferable as a more sustainable, targeted, and optimised approach to veterinary care than blanket medication. This method has the potential to minimise environmental impacts by reducing the amount of veterinary medicines entering soil and water systems, which is often associated with excessive medication e.g. routine whole herd/flock treatments

Other benefits include:

• reducing the likelihood of resistant pathogens developing
• improving the overall health and welfare of animals by mitigating potential side effects through customised dosages and tailored medication based on each animal’s specific needs
• encouraging a proactive approach to animal health through better herd management practice and improving hygiene
• enhancing food safety by reducing the risk of drug residues in food products of animal origin

However, selective treatment practices are not without risks, such as the possibility of failing to treat animals that are carriers of infectious diseases but show no symptoms, which could lead to disease spreading within a herd or flock untreated. Implementing a TST strategy requires careful consideration, particularly in areas with high environmental pest and pathogen pressure.

We recommend that further research is needed to improve understanding of TST indicators for treatment, such as faecal egg count, weight gain, body condition, milk yields, and to optimise and automate these processes as effectively as possible. Research can also help to identify those animals that can remain productive and require fewer treatments, even in the face of parasite challenge, which can help improve the genetics of the whole flock / herd.

• selective treatment should be encouraged through highlighting cost-effectiveness, addressing challenges, and showcasing economic benefits. Examples or case studies showing cost savings from selective treatment – such as conducted for sheep by SRUC and Moredun through the RESAS Strategic Research Programme over the last ten years - can help encourage its adoption. The selective treatment itself may be less labour-intensive especially if it can be automated e.g. use of Cotter Crate for sheep and lamb handling. However, the need for sample collection and laboratory testing can pose challenges to the process. Additionally, the low cost of chemicals used in routine preventative treatment may hinder the adoption of selective treatment strategies, especially if treating all animals is cheaper than testing and treating only the infected ones. Successful examples of selective treatment strategies that provided economic benefits should be highlighted to promote wider adoption of this practice.

For examples see following studies:

Production impact of a targeted selective treatment system based on liveweight gain in a commercial flock - PubMed

Practices to optimise gastrointestinal nematode control on sheep, goat and cattle farms in Europe using targeted (selective) treatments - PubMed

• improved national-level tracking and recording of veterinary medicine use is essential. The Veterinary Medicines Regulations (VMR) outline the requirements for maintaining up-to-date records of purchased and used medicines. This responsibility falls on the owner or keeper of food-producing animals, complicating access to information on the overall quantities of medicines purchased and used for animal treatment. Additionally, information is currently not recorded in a standardised format, which further complicates data access. AAP recommends a standardised approach to data capture, along with improved access to information, to enable trend analysis of veterinary medicines. Such analysis can help identify areas where reductions in medicine use can be made and facilitate better tracking of effectiveness of selective treatment campaigns, as well as the potential environmental impacts of these medicines
• the actual risks of crop pest, weeds and diseases ideally should be monitored. By assessing the real risk of occurrence and severity, farmers and crofters can determine whether pesticide use is necessary and often take preventative actions to reduce risk rather than treat. An Integrated Pest Management plan (IPM) will help growers assess their individual risks and use pesticides only when the risk is high, ensuring that chemical interventions are employed only as and when necessary
• improving the advice provided to farmers and supporting peer learning. Veterinarians, farm advisors and farmers should receive the necessary support to access the latest research and guidance on husbandry practices that promote sustainable use of veterinary medicines and pesticides. Recommended practices should be tailored to specific livestock and crop situations, soil quality, weather patterns, and pest issues. Policymakers should consider using knowledge-sharing programmes to help build relationships between farmers, crofters, and practitioners. Strengthening these connections will support the adoption of selective treatment strategies and ensure ongoing guidance as new methods are implemented

2. Indicators should be considered to monitor the adverse effects of pesticides and veterinary medicines on the environments and biodiversity.

• a system for monitoring pesticide and veterinary medicine use is essential to ensure sustainable use of both. The Pesticide Use Survey data collected by SASA serves as a valuable resource for understanding all aspects of pesticide usage in Scotland. It is vital that this work continues, and ideally, is expanded. Enhancing records of veterinary medicines, pesticides, insecticides, and herbicides applied on farms in Scotland would improve the ability to quantify their potential environmental impacts, thereby enhancing risk assessment and informing better decision-making in pesticide and veterinary medicine regulation
• data collection and statistical modelling should be used for environmental monitoring. The interactions between pesticides and veterinary medicines in the environment, and their adverse effects on biodiversity and ecosystems are complex. Moreover, many studies on the environmental impacts of veterinary medicines have been limited in scope often focusing on small-scale or laboratory-based experiments. Statistical models can analyse large volumes of environmental data, helping to detects trends over time. Statistics also enable the quantification of relationships between pollution sources and their environmental impacts. However, it is equally important to evaluate different scenarios in real-world setting to validate model predictions. Additionally, modelling can support the assessment of policy interventions by analysing data collected before and after policy implementation
• monitoring efforts should cover a range of species. Monitoring should include non-target species that are not intended to be affected by pesticides or veterinary medicines. Efforts should encompass not only water but also soil and indicator species such as native plants, animals, and insects; for example, a decline in insect numbers can impact species higher in the food chain, such as birds. Using a multitude of indicators will help provide a comprehensive picture of how pesticides and veterinary medicines affect the wider ecosystem and biodiversity. However, care should be taken when analysing data, as the presence of pesticides and veterinary medicines in the environment may not be the only factor impacting population and ecosystem health. Climatic conditions, weather patterns, and land use changes should be also considered when analysing the data

Biological records from Scotland stored by the Biological Records Centre, that is part of the UK Centre for Ecology and Hydrology, should be considered for terrestrial invertebrate trend analysis. However, the robustness of the existing datasets should be assessed before undertaking any analysis to ensure the records are complete and up to date.

3. Risks from pesticides and veterinary medicines will change under a future climate.

• a warming climate has the potential to increase risks associated with use of pesticides and veterinary medicines due to multiple factors in the future

• increased rainfall and flooding can amplify the risk of pesticide wash-off from fields and leaching into nearby water bodies
• changing weather patterns are going to make it more difficult to apply pesticide treatments at the right time under the right conditions
• warming temperatures can limit application windows and lead to suboptimal timing, reducing effectiveness
• increases in non-native pests, weeds and diseases coming into woodland and forest areas may increase the need for more pesticide use in areas of planted trees and tree nurseries
• global warming may create better habitat for pests and pathogens as many tend to prefer warm, humid climate and milder winters. Early planting can also exacerbate risks
• animal health will be impacted by an increase in diseases associated with wetter and warmer conditions, such as flukes, as well as emergence of vector-born diseases such as Bluetongue, Schmallenberg, Lyme disease, Tick-borne Encephalitis or Louping-ill. The emergence of these diseases will also depend on livestock management practices, such as increased grazing outdoors, overwintering, grazing near trees or contact with wildlife

The development of new, highly selective pesticides could reduce the overall environmental risks associated with pesticides and veterinary medicines. Some RNA-based pesticides, which use genetic material to specifically target pests and diseases, have the potential for very precise targeting. This precision could reduce the quantities needed to control the spread of diseases and minimise unintended consequences for non-target species.