Prioritisation of veterinary medicines in the UK environment

A wide range of veterinary medicines is used to treat animals in the UK. Whilst the environmental impact of selected substances (particulary the sheep dip chemicals, anthelmintics and fish farm chemicals) has been well studied, limited information is available in the public domain on the other groups of substances (e.g. antifungals, coccidiostats, antiprotozoals, hormones and growth promoters). There is therefore a need to identify other substances that may impact the environment in order to design national monitoring programmes, target experimental work and develop pollution prevention methodologies. In this study, a simple two-stage prioritisation scheme was developed and applied to veterinary medicines in use in the UK. In the first stage, those substances that have high potential to enter the environment in significant amounts were identified on the basis of amounts used in the UK, treatment type and metabolism. In stage 2, the hazard of the identified substances to terrestrial and aquatic organisms was assessed. Using the approach, a total of 56 substances or groups were assigned to a 'high priority' category. For eleven of these substances, sufficient data were available to characterise their risk, these were: oxytetracycline, chlortetracycline, tetracycline, sulphadiazine, amoxicillin, diazinon, tylosin, dihydrostreptomycin, apramycin, cypermethrin and sarafloxicin. For the remaining 45 substances, full datasets were not available and it is recommended that in the first instance, attempts are made to fill these data gaps.