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Microplastics and Organic Leachates in PET Bottled Water Under Heat/Sunlight and Freezing Storage in Port Harcourt, Nigeria

Osemwegie F., Ngah S. A., Egobueze F.

Abstract

The widespread dependence on polyethylene terephthalate bottled water in Nigeria, combined with tropical storage conditions and common consumer practices such as freezing, raises concerns about microplastic and chemical leachate contamination. This study assessed the occurrence, abundance, and morphological characteristics of microplastics, alongside organic chemical leachate profiles, in commercially available PET bottled water (1.5 L) subjected to three storage conditions over five days: unexposed control (22 ± 2°C, dark), heat/sunlight exposure (outdoor, direct sunlight), and freezing (−18°C with one thaw cycle at 72 hours). Each condition was represented by one bottle, split into two aliquots for microplastic characterisation and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Particles were identified by stereomicroscopy and optical microscopy using standardised visual criteria; polymer identity was not confirmed by FTIR or Raman spectroscopy. Results showed a mean particle count of 20.00 ± 2.00 in the control, 10.00 ± 2.00 under cold storage, and 27.00 ± 2.00 under heat exposure, with statistically significant differences among all groups (one-way ANOVA: F(2,6) = 54.750, p < 0.001; Tukey HSD: all pairwise p < 0.05). Fragments dominated (64.3%), followed by fibres (32.2%) and films (3.5%); films occurred only in the heat-exposed sample. Most particles (67.8%) were 1–5 mm. GC-MS screening produced tentative phthalate-related library matches in all samples, with the principal dimethyl phthalate -associated peak Area% following the order heat exposure (0.76%) > control (0.46%) > cold storage (0.11%). The parallel ranking of particle abundance and DMP-associated signal (heat > control > cold) provides preliminary evidence that heat exposure may elevate both particulate and chemical contamination burdens in PET bottled water. These findings suggest the need for larger, spectroscopically confirmed studies to inform regulatory standards for microplastics in Nigerian packaged water.

Keywords

Microplasticsbottled waterheat exposurefreezingphthalatesPort HarcourtNigeria

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