National long-term monitoring and risk assessment of various veterinary drug residues in livestock products in the Republic of Korea

Veterinary drugs are widely used to treat livestock diseases, but the emergence of problems related to drug resistance prompted the government of the Republic of Korea to enact laws regulating the use of veterinary drugs in livestock. Monitoring the contents of residual drugs in livestock products at regular intervals is necessary to assess whether the regulations have resulted in the effective management of food product safety and prevent and manage unexpected problems related to this issue. A 2019-2023 livestock product post-marketing monitoring program launched by the Ministry of Food and Drug Safety (MFDS) of the Republic of Korea inspected 1135 livestock products. Sixty-two different veterinary drugs were detected among 167 monitored, with a detection rate of 28.2% (320/1135 samples; chicken [125], pork [114], milk [35], beef [30], and egg [16]). Diclazuril was detected most frequently, followed by flumequine, clopidol, and enrofloxacin. Over the past five years, two samples that did not conform to the regulations were identified to contain 20 and 215 ng/g, diclazuril and toltrazuril sulfone, respectively. The estimation of exposure and risk assessment revealed that the hazard index of diclazuril was below 75%. However, in case of toltrazuril sulfone, it showed a hazard index exceeding 138% in the scenario of the 95th percentile high consumption of chicken. The results of this study may provide a useful reference in initiating more targeted work in the future, such as the further fine-tuning of food safety monitoring programs and developing food safety standards. In future studies, the MFDS shall continue to monitor the statuses of residual veterinary drugs in commercial livestock products.