The exposure levels and health risk assessment of antibiotics in urine and its association with platelet mitochondrial DNA methylation in adults from Tianjin, China: A preliminary study.

There has been extensive research on antibiotics exposure in adults by biomonitoring, but the biological mechanisms and potential risks to human health remain limited. In this study, 102 adults aged 26-44 years in Tianjin were studied and 23 common antibiotics in urine were analyzed by Liquid chromatography-mass spectrometry (LC-MS). All antibiotics were detected in urine, with an overall detection frequency of 40.4% (the detection frequencies of phenothiazines, quinolones, sulfonamides, tetracyclines, and chloramphenicol were 77%, 54%, 24%, 28%, and 49%, respectively.). Ofloxacin and enrofloxacin had the highest detection frequencies (85% and 81%), with median concentrations of 0.26 (IQR: 0.05-1.36) and 0.09 (IQR: 0.03-0.14) ng/mL, respectively. Based on health risk assessment, the predicted estimated daily exposures (EDEs) ranged from 0 μg/kg/day to 13.98 μg/kg/day. The hazard quotient (HQ) values of all the antibiotics except ofloxacin and ciprofloxacin were bellow one, which are considered safe. For all blood samples, the mitochondrial DNA (mtDNA) methylation levels in the MT-ATP6 (ranging between 3.86% and 34.18%) were slightly higher than MT-ATP8 and MT-ND5 (ranging between 0.57% and 9.32%, 1.08% and 19.62%, respectively). Furthermore, mtDNA methylation from MT-ATP6, MT-ATP8 and MT-ND5 were measured by bisulfite-PCR pyrosequencing. The association (P < 0.05) was found between mtDNA methylation level (MT-ATP8 and MT-ND5) and individual antibiotics including chlorpromazine, ciprofloxacin, enrofloxacin, norfloxacin, pefloxacin, sulfaquinoxaline, sulfachloropyridazine, chloramphenicol, and thiamphenicol, indicating that persistent exposure to low-dose multiple antibiotics may affect the mtDNA methylation level and in turn pose health risks.