Challenges Analysing Monitoring Data for an Insecticide Regulated Under Different Frameworks: A case study on cypermethrin in the UK
Cypermethrin is a synthetic pyrethroid used as an insecticide in a wide range of products across various sectors, registered under the PPP (1107/2009), biocide (528/2012) and veterinary medicine (2001/82) regulatory frameworks. An important use in the UK is as an ectoparasiticide in veterinary medicines to treat sheep, cattle and horses. Its high toxicity and presence in surface water bodies has led to it being classified as an EC priority substance in 2013. Public water quality monitoring in the UK has identified exceedances of the EQS (annual average and maximum allowable concentration) and this work investigated potential sources of cypermethrin within catchments with a view to identifying sources, exposure pathways to surface water as well as assessing mitigation measures to promote the achievement of good chemicals status compliance. As part of this analysis, potential veterinary medicine sources were assessed using sales data and spatial analysis for a sheep dominated catchment (i.e. animal density and flock treatment specific to the catchment, analysis of managed grass adjacent to surface water, runoff percentage from grassland) alongside three main exposure scenarios (wash-off from treated animals following rainfall events, hardstanding runoff following spillages and drips during treatment and wash-off from animals fording rivers shortly after treatment). Other agricultural sources such as incorrect disposal of products, use of cypermethrin products for fly control in animal housing and losses from livestock sale yards were also considered. Results from the analysis were compared to water quality monitoring data for the sheep dominated catchment and results on the likely sources driving exceedances are presented. Differences between regulatory environmental risk assessments and actual product practices leading to environmental exposure are discussed alongside the challenges of interpreting water quality monitoring data for chemicals with multiple uses, regulated under different frameworks.
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