Speciation/ Characterisation of Chemicals of Concern in Livestock Farming Systems

Research on the impact of chemicals of concern (CoCs) like pharmaceuticals, antibiotics, pesticides, and sewage pollutants on UK freshwater quality has increased. However, livestock-derived organic matter (LDOM), which includes manure, slurry, urine, and dung, which is an equally important driver of change in freshwater quality has received insufficient attention. LDOM acts as a reservoir for CoCs from veterinary treatments, pesticides, feed additives, and excreta management. These CoCs can persist in the environment, affecting the ecosystem and public health. There is significant knowledge gaps regarding the chemical and ecotoxicological impacts of livestock excreta, influenced by livestock type, production methods, management practices, and climate change. Livestock farming in the UK involved approximately 9.65 million cattle, 32.7 million sheep, 5.15 million pigs, and 183 million poultry in 2020. Cattle and sheep farming is predominantly located in the wetter northern and western regions, utilizing 10 million hectares of grassland, which accounts for 57% of the UK's agricultural land. It has also been reported that over 80% of oestrogen in UK rivers are from livestock production, with cattle excreting oestrogen an order of magnitude higher than humans. This study focus on 198 CoCs quantified in collected livestock excreta (farm manure, dung, slurries, and urine) from six UK cattle and sheep farms using ultra-performance liquid chromatography tandem mass spectrometry which forms part of a bigger study to understand the impact of sheep and cattle farming on UK freshwater quality under different environmental conditions..

This study identified the prevalence of antitubercular agents (isoniazid and isonicotinic acid) and macrolides (clarithromycin N-desmethyl, clarithromycin, erythromycin, and erythromycin N-desmethyl) among other antibiotic class in farm manure, dung, of sheep, dairy and beef cattle and slurries of cattle, while in the urine of the mentioned livestock, macrolides were prevalent. The detected antibiotics can cause antimicrobial resistance development, influence freshwater biota responses and pose a risk to human health through the food chain. This study reveals the range of CoCs released to the UK environment by livestock farming and provides some of the essential data required to support new, focused management and policy for livestock farming and UK freshwaters, and to inform the management of veterinary medicines in livestock husbandry.