Fluorescence characteristics of dissolved organic matter (DOM) in bottled drinking water of different countries: A potential risk to public health

Bottled drinking water of numerous brands from different countries, including Bangladesh, Malaysia, Australia, India, Singapore, Norway, Japan, Vietnam, and Taiwan, were studied using three-dimensional fluorescence (excitation-emission matrix, EEM) spectroscopy and multivariate parallel factor analysis (PARAFAC) model. Fluorescent-dissolved organic matter (DOM) components such as microbial processed tyrosine-, fulvic acid (M)-, and tryptophan-like had maximum intensity/concentration at 70.8%, 16.7%, and 12.5% bottled drinking water samples, respectively. The total intensity of all fluorescing DOM components was minimum and maximum in one of the brands from Australia and Vietnam, respectively. Unlike in Japan, the concentrations of DOM components in bottled drinking water were comparable to or higher than groundwater, freshwater, and marine water in Bangladesh, Malaysia, India, and Taiwan. The concentration of Escherichia coli was quantified from its significant correlation equation with the microbial-processed tryptophan-like component. Apart from 60% and 20% of bottled water samples from Malaysia and Bangladesh, the remaining samples of studied countries were medium to very high-risk because of E. coli signatures. The adverse health impacts from previously identified over-acceptable-limit mineral concentrations in bottled drinking water are discussed. DOM components at such concentrations in bottled drinking water also strengthened doubts about the efficiency of conventional water treatment techniques and biofilm control. Economic indicators of the studied countries affirmed that willingness and proper management knowledge are necessary to ensure safe bottled drinking water besides budget and labor wages. PRACTITIONER POINTS: Higher protein-like components intensity than humic-like affirmed microbial abundance Risks for E. coli availability was medium to very high in maximum samples Adverse health impacts for overlimit Pb, Al, and PO₄ ^3- minerals in Bangladeshi brands Inefficiency of drinking water treatment techniques in DOM and biofilm control Importance of labor wage, willingness, and knowledge for drinking water treatment.