In situ evaluation of genotoxicity and cytotoxicity associated with microplastics in an intertidal clam, Gafrarium divaricatum (Gmelin, 1791).

Microplastics (MP) are an emerging contaminant posing a significant threat to aquatic biota. While numerous studies have documented diverse pollutant abundances along the Maharashtra coast, in situ data on their impacts are lacking. This study presents the first comprehensive assessment of the spatial distribution of MP in water, sediments, and clams (Gafrarium divaricatum), and evaluates their toxicity. Five sampling stations Aksa (S1), Bandra (S2), Alibagh (S3), Shrivardhan (S4), and Ratnagiri (S5) were selected. Microplastics were quantified and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and a stereo-zoom microscope. Genotoxicity and cytotoxicity were assessed using the comet and clam micronucleus cytome assays (CMNCyt), respectively. Microplastics were abundant in sediment (13,646.35 ± 4565.8 items/kg), followed by water (617.77 ± 214.93 items/L) and clam tissues (74.17 ± 24.80 items/individual). Comet assay showed that % tail DNA, an indicator of DNA damage, ranged from 8.78 ± 0.84 % (Site S5) to 21.15 ± 0.95 % (Site S2) in gill cells, and from 9.33 ± 0.41 % (Site S5) to 23.95 ± 1.38 % (Site S2) in intestine cells. Similarly, cytome assay revealed a range of total cellular abnormalities from 3.14 % to 12.00 % in gill cells and from 5.27 % to 17.61 % in intestine cells. The occurrence of MP and toxicity assays in G. divaricatum indicated a decreasing trend in contamination from S2 to S5 (S2 > S1 > S3 > S4 > S5), reveal that MP has a serious concern for aquatic biota particularly in the Mumbai region, highlighting the need for remedial measures and policies to mitigate plastic pollution and promote sustainable coastal management.