Combined pollution of antibiotics and microplastics in livestock breeding process: Occurrence and correlation

The rapid expansion of intensive livestock farming has raised significant environmental concerns, particularly regarding the emerging issue of combined antibiotic-microplastic pollution. Nevertheless, systematic investigations into their co-occurrence and interactions within farming ecosystems remain limited. In this study, an integrated assessment of antibiotics and microplastics across four environmental matrices (feed, manure, soil, and sewage) from representative livestock farms in South China was conducted. Antibiotics were widely detected, exhibiting the highest concentrations in manure (427–57,217 ng/g; mean 14,406 ng/g) and sewage (58.9–78,346 ng/L; mean 18,151 ng/L). Sulfachloropyridazine (SCP) and tetracycline hydrochloride (TC) were identified as dominant compounds. Soil receiving livestock effluents exhibited antibiotic concentrations more than four times higher than control soil, confirming livestock activities as a major contamination source. Unexpectedly, microplastics were most abundant in feed (4896–25,223 particles/kg; mean 12,564 particles/kg), indicating it as a critical entry pathway into farming systems, with acrylate copolymer (ACR), polyethylene (PE), polyurethane (PU), and polyvinyl chloride (PVC) as the predominant polymers. These findings highlighted feed production, packaging, and storage as key stages contributing to microplastic contamination. Correlation analysis revealed a weak negative association (r = −0.46) between total antibiotics and microplastics, suggesting divergent environmental sources and fates. These findings elucidate critical pollution linkages across the livestock farming chain, providing essential evidence for developing targeted strategies to control co-contamination by antibiotics and microplastics.