Tracing ivermectin residues in swine farms: from treatment approaches to environmental impacts

Pharmaceutical residues, particularly active pharmaceutical ingredients, have become significant environmental pollutants, with their impact extending across ecosystems and affecting public health. Veterinary pharmaceuticals are a major source of contamination, introduced through livestock excretion, manure application, and surface runoff, with different administration routes posing different environmental risks. Chronic environmental exposure to active pharmaceutical ingredients contributes to antimicrobial resistance, behavioral changes, reduced fertility, and biodiversity loss in wildlife. Efforts to mitigate pharmaceutical pollution align with global sustainability goals, such as the UN’s Sustainable Development Goals, emphasizing responsible consumption and protection of ecosystems. Regulatory frameworks, including the EU Water Framework Directive and action plans on pharmaceuticals, aim to address this issue. Despite numerous advancements in therapy, animal welfare, wastewater treatment, and nature-based solutions, drugs may remain persistent in the environment, necessitating sustainable pharmaceutical practices and ecotoxicological research to safeguard environmental and public health. Ivermectin (IVM), a widely used antiparasitic drug in veterinary medicine, plays a critical role in managing parasitic infections in livestock. However, its widespread application raises concerns about its potential environmental impacts, particularly in swine farming systems. This PhD thesis investigates the detection, environmental fate, and ecological consequences of IVM residues in swine farms, as well as their effects on gut health, providing insights into sustainable livestock management practices and One Health implications. An analytical method using HPLC-DAD and, subsequently, LC-MS/MS were developed and validated for detecting IVM in various matrices, including feces, slurry, wastewater, and soil. The method demonstrated high sensitivity, precision, and robustness, with limits of quantification as low as 1.5 µg/kg, highlighting its utility in ecotoxicology and environmental monitoring. The findings showed that IVM residues predominantly accumulated in feces and soil, with no detectable concentrations in slurry or wastewater samples. This accumulation underscores the potential risks to non-target organisms. The research also explored the ecological pathways of IVM residues, revealing differences in residue excretion profiles between oral and injectable administration routes. Injectable formulations resulted in higher concentrations over a long period, while the oral treatment showed an initial higher peak in concentration, but the concentrations were significantly lower 10 days after treatment. These findings highlight the importance of administration routes in assessing the environmental impacts of veterinary pharmaceuticals. Additionally, this research is the first to document the effects of IVM treatment on the gut microbiota of sows. The data demonstrated that IVM treatment significantly altered gut microbiota composition, raising concerns about potential long-term implications for animal health and antimicrobial resistance. This thesis contributes to the growing understanding of veterinary pharmaceutical residues’ environmental and ecological impacts. By addressing critical gaps in analytical detection, residue pathways, and microbial effects, it underscores the importance of sustainable livestock management practices. These findings advocate for integrated One Health approaches to mitigate the environmental footprint of veterinary drugs while safeguarding animal and ecosystem health.