The study investigated human exposure to emerging contaminants in drinking water, focusing on per- and polyfluoroalkyl substances (PFAS), bisphenol A, and nonylphenol. These chemicals are prevalent due to widespread industrial and consumer use, posing significant health risks. PFAS, known for their persistence and resistance to degradation, have been linked to various adverse health outcomes, including reduced birth weight, increased cancer risk, and impaired metabolic function. While some legacy PFAS compounds like PFOA and PFOS have been phased out, replacement PFAS, such as GenX and ADONA, are increasingly detected. Bisphenol A and nonylphenol, endocrine-disrupting chemicals, also present health concerns due to their presence in various consumer products and potential for bioaccumulation. The EU Drinking Water Directive (EU DWD 2020/2184) highlights the public health concern by setting maximum contaminant levels for PFAS and bisphenol A, and including nonylphenol on the watch list. This study aimed to assess human exposure to these chemicals in Barcelona, Spain, using both targeted and non-target analysis of drinking water and urine samples. The objectives were to quantify the occurrence of PFAS, bisphenol A, and nonylphenol in different water types (tap, filtered tap, bottled), to evaluate human exposure to PFAS via urine analysis, and to identify other emerging contaminants through non-target screening of tap water samples.

Existing literature highlights the presence of PFAS in various environmental matrices, including drinking water, with varying levels of concern depending on the specific compounds and geographical location. Studies from Canada, China, India, the USA, and several European countries have assessed PFAS levels in treated drinking water, but information, particularly from Europe, remains limited, especially regarding background levels in areas not directly impacted by point source contamination. The literature also documents the presence of bisphenol A and nonylphenol in the environment and their association with various health problems. However, data on their occurrence in different types of drinking water is sparse. The review underscores the need for comprehensive monitoring and risk assessment of these emerging contaminants in drinking water supplies to protect public health.

The study involved collecting samples from 42 locations in Barcelona, Spain, across two sampling campaigns (August-October 2020 and May 2021). Samples included unfiltered tap water, tap water filtered with activated carbon (AC) filters (n=6) and reverse osmosis (RO) filters (n=5), bottled water (n=10), and urine samples (n=39). A total of 35 PFAS, bisphenol A, and nonylphenol were analyzed using LC-MS/MS and GC-MS/MS. Non-target screening (NTS) using LC-HRMS was also performed on tap water samples to identify other emerging contaminants. Sample preparation involved online SPE for PFAS analysis in drinking water, offline SPE for urine samples, and liquid-liquid extraction for bisphenol A and nonylphenol. Detailed analytical methods, including instrument parameters, are provided. Data analysis encompassed descriptive statistics, Spearman rank correlation coefficients to assess relationships between PFAS concentrations, and paired t-tests to evaluate filter removal efficiency. The study also collected data on participants’ demographics, water consumption habits, and utilized statistical software (R) for data processing.

Nine PFAS were detected in unfiltered tap water samples in the first sampling campaign (79% of samples, median 30 ng/L), with perfluoropentanoate (PFPeA), perfluorobutane sulfonate (PFBS), perfluoroheptanoate (PFHpA), perfluorohexanoate (PFHxA), and PFOS being the most frequent. In the second sampling campaign (May 2021), six PFAS were detected in 69% of samples (median 9.8 ng/L), with PFPeA and PFBS predominating. The study noted a three-fold difference in median total PFAS concentrations between the two sampling campaigns, possibly due to seasonal variations in water source quality. AC filters did not effectively remove PFAS, while RO filters achieved a 97% reduction in median PFAS concentrations. Bisphenol A and nonylphenol were not detected in tap, filtered, or bottled water. Five PFAS were detected in 13% of urine samples, suggesting drinking water might be a source for some compounds, but other sources may contribute to the detection of others. Non-target screening identified several pharmaceuticals, pesticides, industrial chemicals, and personal care products in tap water. Carbamazepine, tris(chloroisopropyl) phosphate, suberic acid, and azelaic acid showed high detection rates. RO filtration effectively removed these compounds compared to AC filtration. The study notes that the sum and total PFAS concentrations, as defined by EU DWD, were identical because only carboxylates and sulfonates C4-C12 were detected.

The findings highlight the presence of various emerging contaminants, especially PFAS, in Barcelona's drinking water. The dominance of shorter-chain PFAS (<C8) reflects the shift in fluorochemical industry towards these “replacement” compounds, which, although initially considered safer, have raised concerns about their persistence and potential health effects. The study's observed seasonal variation underscores the importance of continuous monitoring, considering that factors like rainfall and dilution might influence source water quality. The ineffectiveness of commonly used AC filters in removing PFAS highlights the need for more effective treatment technologies like RO. The detection of various other chemicals points towards diffuse source contamination from industrial and urban activities. Further research is necessary to investigate the specific sources of these compounds and their potential long-term health implications. The study's limitations, including spot urine samples and the tentative nature of some NTS findings, should be considered.

The study provides valuable insights into human exposure to emerging contaminants, emphasizing the widespread presence of PFAS in Barcelona's drinking water. The findings highlight the limitations of AC filtration and the effectiveness of RO treatment for PFAS removal. The detection of other micropollutants underscores the complexity of drinking water contamination. This research advocates for continuous monitoring and the exploration of advanced treatment technologies for ensuring safe drinking water. Further studies are necessary to investigate the long-term health consequences of exposure and to refine our understanding of the sources and transport pathways of these contaminants.

The study utilized spot urine samples, which may not fully reflect long-term exposure. The non-target screening results were tentative identifications, requiring confirmation through reference standards for accurate quantification and structural elucidation. The small number of samples (n=6) for AC and RO filtered water, and the limited number of participants reporting consuming these filtered water types might affect the representativeness of those results. The study's geographical focus on Barcelona may not be generalizable to other regions with different water sources and treatment practices.