First report on microplastics in a freshwater clam, Corbicula baudoni, in Vietnam

Abstract

The widely reported microplastic presence in aquatic animals has been concerned due to the potential ecological and human health risks. The microplastics in marine mollusk have been studied worldwide, however, information on microplastics in freshwater mussels has been limited. In this study, we monthly monitored microplastics in small (mean length of 14 mm, weight of 1.1 g) and large (mean length of 21 mm, weight of 3.6 g) sizes of freshwater clam (Corbicula baudoni) from Mekong River in Dong Thap Province, Vietnam, from February to September 2022. Two microplastic shapes of fiber (99%) and fragment (1%) were observed in tissue of all clam samples. The microplastic abundance (mean ± standard deviation) in the small size clams was 3.4 ± 1.4 items/individual, and 15.8 ± 9.9 items/g wet weight, whereas that in large size clams was 14.6 ± 10.0 items/individual, and 18.2 ± 14.2 items/g wet weight. We found a positive correlation between the microplastic abundance in the clams and their size and weight. In all clam samples, the shorter fibers were the higher numbers they were. Seven microplastic colors were observed in which the highest proportion of the colors was black (∼ 40%), followed by white (∼ 26%), and blue (∼ 17%). The polymeric characterization by the Fourier Transform Infrared Spectrometry revealed that the items were polymers of polyethylene terephthalate, polypropylene, polyethylene, polyacrylonitrile, nylon, and rayon. To the best of our knowledge, this is the first report on microplastics in freshwater clam from Mekong River and in Vietnam. The common presence of microplastics with high abundance in the clams indicates a high potential health risk to local inhabitants who daily consume the clams as food. Further studies on the effects of microplastics from food on human health are highly suggested.