Short-term depuration reduces the levels of microplastics of a commercial mussel from Eastern Amazon

Abstract

Consumption of contaminated shellfish can be a pathway of human exposure to microplastics (MPs). Depuration is a treatment step that can effectively reduce the particle content of bivalves; however, this technique is not yet employed for mussels sold in the Eastern Amazon coast, in Brazil. Hence, this study aimed to verify the efficacy of 24 h, 48 h, and 72 h depurations in reducing the MP concentrations of the native mussel Mytella guyanensis . A total of 176 MPs were observed among fibers, fragments, and pellets, with black and blue fibers being predominant, followed by blue fragments. Non-depurated mussels had a significantly higher concentration of MPs per gram of edible weight than mussels from all depuration periods (1.31 ± 1.19 MPs/g). Meanwhile, in the concentration per individual non-depurated mussels (2.17 ± 1.04 MPs/ind) had a significantly higher contamination than mussels depurated for 48 h (1.33 ± 0.67 MPs/ind) and 72 h (0.90 ± 0.78 MPs/ind). Dyed fibers and fragments represented most of the observed MPs (58%), followed by microplastics of different polymers (25%), and cellulose (16%). Among dyes, the textile pigment Indigo and general use phthalocyanines were the most common findings, while PP was the most common microplastic. Our results reveal ample contamination by MPs in mussels that supply markets in the region. Therefore, we infer that depuration is an effective way of reducing the particle content of M. guyanensis , with the potential to reduce the human MP intake by 55–58%, considering a 72-h depuration.

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