Potential human consumption risks from microplastics and non-synthetic microfibers in cultured oysters from a low-human-impact lagoon

Coastal lagoons are ecologically and economically important ecosystems, serving as nursery areas for marine species, providing coastal protection, and filtering pollutants. Despite their significance, these environments are increasingly exposed to various contaminants, including microplastics (MPs) and non-synthetic microfibers (NSMs), which are pervasive in ecosystems worldwide. Due to their size, they can be ingested by marine organisms and transferred to higher trophic levels, posing a risk to marine life and human health. NSMs and MPs were identified and quantified in farmed oysters (Magallana gigas) and in surface water, bottom water, and sediments from a rural coastal lagoon in Baja California, Mexico. Once the samples were collected, the organic matter was removed, filtered, and finally, the particles were separated according to their shape, color, and size. The chemical composition of the particles was analyzed using μ-FTIR-ATR. The most frequently identified polymers were cellulose, cotton, and polyester, common across all matrices. Polypropylene was predominant only in surface water samples. These findings highlight the diverse sources and potential behaviors of MPs and NSMs in the lagoon. Although the lagoon experiences low anthropogenic impact and limited runoff, it is not exempt from pollution. The detection of MPs and NSMs in water, sediment, and oysters reflects the vulnerability of coastal lagoons to pollutants. It suggests a need for continued monitoring better to understand potential implications for ecosystem and human health.