Environmental risk of microplastics in a Mexican coastal lagoon ecosystem: Anthropogenic inputs and its possible human food risk

Coastal lagoons are ecosystems that are considered providers of a variety species of commercial value to the humans. However, they are currently threatened by a variety of anthropogenic-derived impacts, including environmental pol-lution by microplastics (MPs). For these reasons, it is necessary to identify suitable biomonitors for monitoring MP ac-tivities in aquatic environments and for estimating human ingestion of MPs from the consumption of commercial shellfish species. Therefore, our aims were to identify the anthropogenic activities that supply MPs into a coastal la-goon in the southern Gulf of Mexico and their variety; to determine whether oysters (Crassostrea virginica) are suitable biomonitors to perform MPs monitoring activities and to conduct an estimation of how many MPs could a human con-sume by the ingestion of a commercial portion of oysters harvested in this coastal lagoon. Our results noted that MP concentrations from water and sediment collected in Laguna de Terminos were 210,000 and 11.3 times higher than values reported in other protected areas worldwide. MPs chemical composition revealed that fishing and urban activ-ities supply mainly polyethylene (21.1 %), poly (butadiene) diol (12.6 %) and polyethylene terephthalate (9.5 %). It was also determined that oysters did not reflect the spatial distribution of MPs within the study area and that a human could consume up to 806.1 MPs per 237.1 g serving of an oyster cocktail. Finally, a coastal lagoon polluted with MPs increases the risk of affecting species used for human consumption.