OCCURRENCE OF METFORMIN IN ENVIRONMENTAL WATER SAMPLES AND COMPARISON WITH CONSUMPTION DATA FROM A SURROUNDING HOSPITAL OVER 5 YEARS: A RETROSPECTIVE CASE STUDY.

Context: The environmental occurrence of metformin has been frequently world-widely reported. Despite the diabetes susceptibility in the Chinese population, the studies on occurrence of metformin as environment disruptor in China are insufficient.

Objective: To determine the occurrence trends and possible environmental pollution sources of metformin as an emerging micropollutant.

Methods: High-performance liquid chromatography-electrospray ionization-tandem mass spectrometry system was used to detect the metformin levels in water samples collected from the Xi'an city Moat, China once a year from 2017 to 2021. Correlations among the metformin levels in moat water, in surrounding hospital wastewater, and hospital metformin consumption data were assessed using Pearson, Spearman and Kendall's tau-b correlation coefficients.

Results: Occurrence of metformin was found in Xi'an city Moat water with levels in the range of 304-793 ng/L. Significant correlations were found between the metformin levels in city moat water and the total (or outpatient) metformin utilization data of the hospital.

Conclusion: Data suggested the potential environmental issues posed by metformin in Xi'an city in China. The metformin consumption volume in the surrounding hospitals, especially at the outpatient services, could be used to predict the metformin concentrations in the moat water.