Detecting Micro-Plastics in Bottled Water

Abstract

Microplastics are anthropogenic contaminants that have been accumulating in surface water bodies for the past several decades. Little is known on the presence of microplastics in drinking water in the Middle East region in general and Lebanon in specific. In this study, microplastics occurrence in plastic bottled water was assessed. 17 samples were prepared by filtering water through Nucleopore track-etched Polycarbonate filters (Whatman, 0.2 μm pore size and a diameter of 47 mm) using a vacuum filtration setup inside a biosafety cabinet. 12 of those samples were made up of two, two-liter water bottles and 5 of those samples were blank samples that were prepared by filtering one liter of UltraPure water. Filter samples were analyzed using scanning electron microscopy (SEM). 30% of each filter sample area was analyzed to determine the number of micro-particles/L. The plastic bottles contained 23,702 ± 3793 micro-particle/L and the blank contained 8353±633 microparticles/L. The micro-particles were divided into four size groups which are: less than 1 μm, 1-5 μm, 5-10 μm, and 10+ μm. Among all the categories, the 1-5 μm showed the highest number of particles accounting for 14,454±2703 particle/L. A sample of the micro-particles in each sample were analyzed and using the atomic and weight percentages of each particle, a microplastic (MP) percentage estimate was calculated. Sample analysis reveals MPs in plastic bottles amount to 10,134± 2,184 MP/L and 3,656±768 MPs/L in blank samples. Therefore, around 50% of the total particles detected are plastics. the amount of MPs/L was 86.6 times greater than the study done by (Schymanski, Goldbeck, Humpf, & Fürst, 2017) that reported 118±88 MPs/L. Furthermore, when compared to the study done by (Oßmann, et al., 2018) the number of MPs/L is 3.9 times greater than the single use PET bottles which was 2,649±2857 MPs/L and 2.1 times greater than the new reusable PET bottles which was 4,889±5432 MPs/L and 1.2 times greater than the old reusable PET bottles which was 8,339±7043 MPs/L. This discrepancy in the studies might be due to either different brands used in the studies and/or the difference in methodology. The experiments show that MPs are present in every water bottle sample as well as the blank samples. The abundance of the plastics that are less than 5 μm poses a concern since they can be absorbed by the human body and eventually accumulate in it. Future work includes using μ-Raman spectroscopy or μ-FTIR to identify the type of plastic present in bottled water.