Polymers of micro- and nanoplastics in household tap water of Barcelona

BACKGROUND AND AIM. Microplastics are emerging persistent pollutants present in drinking water. Previous studies evaluate 100-5 m particles, although smaller sizes are more biologically relevant and evidence suggest higher occurrence levels at the lowest range. However, analytical challenges to determine smaller particles result in limited population-based studies. We describe the concentrations of microplastics in the public drinking water network of Barcelona, Spain, through a novel workflow to quantify polymers of micro-and nanoplastics(MNPLs) in 0.7-20 m range. METHODS. We conducted a cross-sectional study including 42 households(one per postal code), with home visits to collect tap water samples(5L). We conducted water fractionated filtration followed by toluene ultrasonic-assisted extraction and size-exclusion chromatography, using an advanced polymer chromatography column coupled to high-resolution mass spectrometry with atmospheric pressure photoionization source with negative and positive ionization conditions (HPLC(APC)-APPI(±)-HRMS) and normal phase chromatography HILIC LUNA® column and electrospray ionisation source in positive and negative mode (HPLC(HILIC)-ESI(±)-HRMS). Polymers were identified based on monomer characterisation through Kendrick Mass Defect analysis, plus confirmation and quantification using standards. A principal component analysis(PCA) was conducted to assess differences between the two areas supplied by different drinking water treatment plants. Analysis of bottled water samples are ongoing. RESULTS. Polyethylene (PE), polypropylene (PP), polyisoprene (PI), polybutadiene (PBD), polystyrene (PS), polyamide (PA), and polydimethylsiloxanes (PDMS) were identified. PE, PP, and PA were the most highly detected polymers, and PI and PBD were found at the highest concentrations (9 and 1.9 μg/L, respectively). PCA showed no significant differences between the drinking water suppliers. CONCLUSIONS. Citizens in Barcelona are exposed to MNPLs through drinking water, at variable concentrations depending on the polymer. The analytical method allows to analyse a smaller fraction compared to previous studies. Epidemiological research is needed to evaluate associated health risks KEYWORDS: Drinking water, microplastics, nanoplastics, exposure, tap water, laboratory analysis, high-resolution mass spectrometry