Development of pesticide load indicators

AERU have undertaken several projects over the decades that have sought to develop metrics that serve as an indicator of the environmental load or risk posed by the agricultural use of pesticides. The most recent of these is an ongoing project funded by Defra to develop a UK pesticide load indicator. This project, and its predecessors, are outlined below.

2024-2024: Development of a pesticide risk indicator for the Convention on Biological Diversity

AERU are contributing to an expert group, convened by the Food and Agriculture Organisation of the United Nations (FAO), to help develop a methodology for Headline indicator 7.2 under the monitoring framework of the Kunming-Montreal Global Biodiversity Framework (adopted at COP 15). The work is contributing to the review of component and complementary indicators related to pesticides and the results will be provided to the Ad Hoc Technical Expert Group (AHTEG) on Indicators that was established through Decision 15/5 to support work on the monitoring framework.

2021-2021: Development of a farm-based PLI indicator

This small consultancy project is developing a farm-level Pesticide Load Indicator, based on the Danish approach, to assist with safer pesticide selection.

2021-2021: Development of a pesticide load indicator for Latvia

This is a small collaborative project with Latvia University to develop a pesticide Load Indicator for Latvia based on the original indicator developed by the Danes and drawing on data in the PPDB. This work will benefit from the lessons learnt for problem mitigation derived from the development of the UK Pesticide Load Indicator.

2019-2023: Development of a UK pesticide load indicator (Ref. PC0102)

This project aims to develop a standardised UK Pesticide Load Indicator (UK PLI) which can be used to help policy and other stakeholders understand changing pressures on the environment and human health associated with pesticide use. The UK PLI is based on an indicator developed in Denmark, where it has been used as a key component of monitoring and pesticide policy. The indicator is formed of three sub-indicators representing environmental fate, toxicity for non-target organisms and human health concerns. These sub-indicators are themselves calculated based on weighted standardised measures compiled as part of the Pesticide Properties Database (PPDB). The per kilogram value of the indicator can then be combined with estimates of the mass of application (based on the UK Pesticide Usage Survey (PUS)) to examine patterns in load across space and time.

The work will develop, in collaboration with relevant stakeholders, a version of the UK PLI which accurately reflects the concerns of UK policy and which helps to resolve some of the outstanding issues associated with the Danish indicator. This will include: establishing the appropriate weighting for the underlying measures such that values are reflective of UK policy concern and are transparent to policy and other stakeholders; reworking how environmental fate is represented in a UK context with a particular focus on soil types and how these influence observed variation in load between UK regions; and redefining how the indicator represents human health concerns, replacing the existing reliance on ‘risk phrases’ for operator exposure with measures that scale proportionally to the mass of application.

This project is funded by the Department for Environment, Food and Rural Affairs (Defra) and will be undertaken in collaboration with Fera Science.

2018-Ongoing: Species specific alert systems

AERU have been working with BeeWatch and the World Owl Trust to develop mobile phone app indicator alert systems. Drawing on data in the PPDB, the apps provide alerts on potential hazards to either honey bees and bumble bees, or owls (as well as those for birds, fish, aquatic invertebrates and humans) using a simple 'traffic light' system. The app can be used by land managers to log their pesticide use and any nearby beekeepers and/or landowners can then be alerted to any potential hazards and thus take action to mitigate any issues.

2013-2014: Waitrose pesticide load indicator

In order to inform and improve its policy on encouraging the use of safer and more sustainable crop protection chemicals, Waitrose have collaborated with AERU to develop an indicator approach to identifying risks to human health, biodiversity and the environment, such that they and their growers world-wide will be able to develop more benign crop protection programmes. The indicator aims to: help minimise the effect on biodiversity and, in particular non-target species; help replace older chemistry with more up to date science; respect new legislation and protect surface waters and groundwaters; help promote the uptake of Integrated Crop Management; and project farm works and the general public.

2002-2003: Comparison of the environmental risk of pesticides used in conventional and integrated farming systems for farms

This was a relatively small pilot project looking (retrospectively), at the pesticide data collected during the LINK IFS study carried out by ADAS and others. The LINK project set out to compare (financially and environmentally) conventional, organic and integrated management systems. During the time of the LINK project techniques to assess the environmental impact of pesticides were still in their infancy and comparisons were made on the basis of the amount of active substance used. AERU in collaboration with Central Science Laboratory (CSL) and National Soil Resources Institute (Cranfield University) developed a new state-of-the-art technique (p-EMA) to assess the fate and environmental risks of pesticides. This project was commissioned by the Department for Environment, Food and Rural Affairs (DEFRA) to apply p-EMA to three of the original nine LINK project sites (Boxworth and Sacrewell in Cambridge and Lower Hope in Herefordshire), with the aim of improving on the original comparison process.

The project was carried out in collaboration with ADAS Mowthorpe and supported by the organisations below. It is anticipated that the pilot project will be extended to cover all of original the LINK project sites.

1998-1999: Concerted Action of Pesticide Environmental Risk indicators (CAPER)

This project addressed the need for more information on the environmental impact of pesticides. The objective being to exchange information between European research groups and to reach a consensus on methods to translate data on the environmental impact of pesticides into a ranking or scoring system. The specific objectives of this concerted action were: to compare and discuss existing methods of scoring and ranking pesticides according to their environmental impact; to formulate recommendations for the improvement of existing methods in relation to the purposes for which they can be used; and to disseminate results to other interested organisations which can benefit from it.

CAPER was finished in June 1999. Eight indicators were described in detail, compared and evaluated. Because of the large differences in purpose, effects taken into account and methodology used, the outcomes of the indicators varied as well. However, the outcomes per environmental compartment and effect showed a significant correlation and differences were explained by the differences in methodology. During the project, requirements were defined which indicators should meet, e.g. reflect risk rather than hazard, give information on separate environmental risks, are consistent with the authorisation of pesticides. The project recommended the development of a harmonised scientific framework for the development of indicators in the EU.

1998-1999: Development of environmental banding for the Government's proposed pesticide tax

AERU were involved in a research project to design a pesticide tax / charge scheme for the UK. The work was funded by Department for the Environment, Transport and the Regions (DETR) and was led by ECOTEC in collaboration with AERU, Central Science Lab (CSL), the University of Newcastle Upon Tyne and Economics for the Environment Consultancy (EFTEC). The specific role of AERU was to develop a system that would band pesticides according to their potential environmental impact. This banding would then be used to set different levels of tax/charge, with the aim of setting a higher tax/charge for more environmentally damaging pesticides to discourage their use.


  • Rainford, J, Tzilivakis, J., Garthwaite, D., Jones, G. & Lewis, K.A. (2023). Finalising a Pesticide Load Indicator for the UK: Phase 4 Report. Prepared for the Department for Environment, Food and Rural Affairs (Defra), UK, for project PC0116, by FERA Science Ltd and the Agriculture and Environment Research Unit (AERU), University of Hertfordshire, UK. [Download].
  • Lewis, K., Rainford, J., Tzilivakis, J., & Garthwaite, D. (2021). Application of the Danish Pesticide Load Indicator to UK arable agriculture. J Environ Qual.: 1-13. DOI.
  • Rainford, J., Garthwaite, D., Jones, G., Tzilivakis, J. and Lewis, K.A. (2020) Developing a UK Pesticide Load Indicator. Final report for a scoping project undertaken for Defra by FERA Science Limited and the Agriculture & Environment Research Unit at the University of Hertfordshire.
  • Lewis, K.A. & Tzilivakis, J. (2019). Wild bee toxicity data for pesticide risk assessments. Data4(3): 98. DOI
  • Lewis, K.A. & Tzilivakis, J. (2013). The Waitrose Pesticide Load Indicator. Waitrose Annual Technical Conference for the Fresh Produce Supply base, 13 November 2013.
  • Tzilivakis, J., Turley, D.B., Ogilvy, S.E., Lewis, K.A. & Lawson, K. (2004). Assessing the environmental impact of crop protection strategies for integrated farming systems. Agronomie 24, 67-76.
  • Reus, J., Leendertse, P., Bockstaller, C., Fomsgaard, I., Gutsche, V., Lewis, K., Nilsson, C., Pussemier, L., Trevisan, M., Van der Werf, H., Alfarroba, F., Blümel, S., Isart, J., McGrath, D. & Seppälä, T. (2002). Comparison and evaluation of eight pesticide environmental risk indicators developed in Europe and recommendations for future use. Agriculture, Ecosystems and Environment 90, 177–187.
  • Reus J., Leendertse P., Brockstaller C., Fomsgaard I., Gutsche V., Lewis K.A., Nilsson C., Pussemier L., Trevisan M., van der Werf H., Alfarroba F., Blumel S., Isart J., McGrath D. & Seppala T. (2000). Comparing environmental risk indicators for pesticides: results of the European CAPER Project. Symposium Pesticide Chemistry, Paper XI.
  • ECOTEC Research and Consultancy, University of Hertfordshire & Central Science Laboratory and the University of Newcastle upon Tyne. (1999). Design of a Tax or Charge Scheme for Pesticides, ISBN 1 851121 60 9, DETR.


Prof. Kathy Lewis



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University of Hertfordshire
University of Hertfordshire, 2023.