PREPP - Producing Rational Evidence for Parasiticide Prescription

The PREPP (Producing Rational Evidence for Parasiticide Prescription) group is an multidisciplinary partnership which unites experts from Imperial College London, collaborating institutions and individuals. As part of the CITE (Chemicals in the Environment) Research Initiative, their work explores and evaluates the environmental risks posed by veterinary medicine pollution to gauge ecological impacts and to explore possible solutions. Our current focus is on contamination by pesticides associated with animal treatment.  We are developing evidence to underpin appropriate advice and inform future policy and legislative action. 

The pathways of pet parasiticides into UK water supplies. Flea and tick treatments and preventatives are toxic, accumulating in freshwaters to concentrations harmful to aquatic species. The work of PREPP evaluates the pathways, impacts and potential solutions to limit the environmental risks posed by common parasiticides.

Our team


Since mid-2022, the team's work has largely focused on the presence of pet parasiticides in urban waterways. This work was summarised in this Grantham Institute briefing paper published in March 2023. Other relevant publications are as follows:

  • Egli, M. et al., A One-Health environmental risk assessment of contaminants of emerging concern in London’s waterways throughout the SARS-CoV-2 pandemic, Environment International, 180 (2023). 
  • Egli, M. et al., Quantitative determination and environmental risk assessment of 102 chemicals of emerging concern in wastewater-impacted rivers using rapid direct-injection liquid chromatography—tandem mass spectrometry. Molecules, 26(8) (2021). 
  • Miller, T, H. et al., Multicompartment and cross-species monitoring of contaminants of emerging concern in an estuarine habitat, Environmental Pollution, 270 (2021). 
  • Miller, T, H. et al., Biomonitoring of pesticides, pharmaceuticals and illicit drugs in a freshwater invertebrate to estimate toxic or effect pressure, Environment International, 129 (2019). 
  • Ng, K, T. et al., High-throughput multi-residue quantification of contaminants of emerging concern in wastewaters enabled using direct injection liquid chromatography-tandem mass spectrometry, Journal of Hazardous Materials, 398 (2020). 
  • Rapp-Wright, H. et al., A year-long study of the occurrence and risk of over 140 contaminants of emerging concern in wastewater influent, effluent and receiving waters in the Republic of Ireland. Science of the Total Environment, 860 (2023). 
  • Richardson, A. K. et al., Rapid direct analysis of river water and machine learning assisted suspect screening of emerging contaminants in passive sampler extracts, Analytical Methods, 13(5) (2021). 
  • Richardson, A. K. et al., A miniaturized passive sampling-based workflow for monitoring chemicals of emerging concern in water. Science of the Total Environment, 839 (2021). 
  • Wells, C., Collins, C.M. A rapid evidence assessment of the potential risk to the environment presented by active ingredients in the UK’s most commonly sold companion animal parasiticides. Environ Sci Pollut Res, 29 (2022). 

Read more articles from the members of our team here: Dr Leon Barron, Dr Tilly Collins, Rose Perkins, Rhys Preston-Allan, Professor Jeff Waage, Professor Guy Woodward.