Antibiotic residues in pork in 3 provinces of Lao PDR and risk assessment

This study investigated the prevalence and residue levels of the antibiotics amoxycillin, ampicillin, oxytetracycline, and tetracycline in pork sold at fresh markets in Vientiane Capital, Luang Prabang, and Champasak provinces of Lao PDR. A total of 72 pork samples were analysed using electrospray ionisation liquid chromatography – tandem mass spectrometry (ESI-LC-MS/MS). Antibiotic residues were detected in 56.9% of the samples and 4.2% exceeded the Maximum Residue Limit (MRL). Tetracycline (47.2%) was most frequently detected, with a mean residue level of 5.3 µg/kg, followed by oxytetracycline (31.9%; mean: 11.8 µg/kg) and amoxycillin (8.3%; mean: 52.3 µg/kg). Ampicillin was not detected in any sample. Health risk assessment using the Hazard index (HI) indicated no health risks under the current dietary exposure. However, the presence of multiple residues in single samples raises concerns about cumulative exposure and potential contribution to antimicrobial resistance, highlighting the need for farmer training, enforcement of withdrawal periods and regular monitoring to protect public health in Lao PDR.