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Biomarker Responses in the Marine Mussel Mytilus Edulis Indicate Significant Toxicological Effects of Polyethylene Microplastics

Bulletin of Environmental Contamination and Toxicology 2026
Omar M. L. Alharbi

Summary

Scientists exposed mussels to microplastic particles for just three days and found real damage: broken DNA, cell stress, and weakened internal cell defenses. Since mussels and other shellfish are commonly eaten and also serve as an early warning system for ocean pollution, this research suggests microplastics in our waters could be causing cellular harm—though more research is needed to know what this means for people who eat seafood or are otherwise exposed to microplastics long-term.

This study investigated the short‑term effects of polyethylene microplastics (PE‑MPs) on the marine mussel Mytilus edulis using a suite of cellular and subcellular biomarkers. A total of 225 mussels were collected from Umluj, Saudi Arabia, a relatively unimpacted coastal area of the Red Sea, and experimentally exposed for 72 h to spherical PE‑MPs (50 μm diameter) at nominal concentrations of 5, 10, 20, and 60 particles L. Genotoxicity, oxidative status, and cellular integrity were assessed by comet assay, thiobarbituric acid‑reactive substances (TBARS), superoxide dismutase (SOD) activity, and lysosomal membrane stability (LMS). At 60 particles L, DNA strand breakage increased markedly in hemocytes (13.09%) and gill cells (12.21%) relative to controls (2.14%; p < 0.01). Lipid peroxidation was 1.28 nmol TBARS mg protein and activity of gill SOD was decreased by 16.13% of control. LMS was significantly reduced from 134.4 min in controls to 53.2 min in the highest exposure (p < 0.01), suggesting impaired cellular homeostasis. Given the short exposure duration, these results are preliminary. They indicate that acute PE-MP exposure at the tested concentrations is associated with measurable genotoxicity, oxidative stress, and reduced lysosomal stability. Longer-term ecological implications remain to be investigated.

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