Identification of microplastics in mollusks using an optical microscope

Abstract Microplastic pollution is currently a global concern. Microplastics accumulate in water and sediments, especially aquatic flora and fauna. Accumulation in animals such as mollusks can directly affect human health via the food chain. The present study aimed to identify microplastics in mollusks using an optical microscope. The factors affecting the decomposition of biological tissues were determined using different agents combined with conditions of time, temperature, and a ratio of agents, as well as the Box–Behnken model, to determine the most suitable conditions for sample preparation. The results showed that using KOH 10% for 24 h at a temperature of 57 °C has obtained the highest protein decomposition efficiency. This procedure was applied to prepare mollusk samples collected in the Can Gio district, Ho Chi Minh City. The microplastic content in mollusk tissues ranged from 1.34 ± 0.7 to 1.61 ± 0.8 MPs g −1 , distributed relatively evenly among species. The microplastics mainly existed in fibers, with sizes ranging from 300–5000 µm, mostly black plastics, that is, 43%–57%.