Microplastics Contamination in Commercial Green Mussels from Selected Wet Markets in Thailand

Mussels have been identified as sentinel organisms (around the world) that indicate microplastic (MP) pollution. Since they are filter feeders, they easily uptake MPs. Mussels sold in commercial markets have been identified as an ideal way to directly quantify human exposure to MPs through seafood consumption. There are no studies reported on MP contamination of market-sold species in Thailand. This study investigates the level of MP contamination in market-sold green mussels, which is a popular seafood in Thailand. A total of 90 green mussels (Perna viridis) collected from three markets were analyzed for the number, polymer types, and morphology of the MPs. Fourier-Transform Infrared Micro-Spectroscopy (micro-FTIR) analysis was used for polymer identification. Nile Red (NR) tagging was used for the enumeration of MPs. MPs were widely discovered in green mussels from all three markets with 100% detection frequency. The average abundance of MPs in green mussels was quantified as 7.32 +/- 8.33 items/mussel and 1.53 +/- 2.04 items/g (wet weight). Ethylene/propylene copolymer followed by low-density polyethylene (PE-LD), polypropylene (PP), and polyethylene terephthalate (PET) were found. Fragments (75.4%) were the most common morphotype, followed by fibers (24.6%). Results indicate that the consumption of green mussels as a food can be one of the exposure pathways for the Thai population. Moreover, smaller size MPs were predominant, which are reported to cause higher impacts.

Automated summary

Mussels are commonly used as sentinel organisms to indicate microplastic pollution worldwide, particularly as a direct way to quantify human exposure through seafood consumption. This study found widespread microplastic contamination in market-sold green mussels in Thailand, with ethylene/propylene copolymer, low-density polyethylene, polypropylene, and polyethylene terephthalate being the most common polymers. Fragments were the dominant morphotype, indicating that the consumption of green mussels may be a significant exposure pathway for the Thai population, especially due to the prevalence of smaller size microplastics with reported higher impacts.