Extraction of microplastics from commonly used sea salts in India and their toxicological evaluation

Microplastics (MPs) are one of the marine debris, accumulated in the ocean as a result of the successive breakdown of a large piece of plastics over several years. MPs are about less than 5 mM, have a detrimental impact on marine organisms/products (seafood/sea salts) and therefore they are considered as a global environmental pollutant. The occurrence and impact of MPs in commercial sea salts that are consumed by humans are not well studied so far. In the present study, we attempted to characterize and evaluate the in vitro toxicity of isolated MPs. Here, we have used ten brands of commercial sea salts of different origins for the identification and characterization of MPs. The average abundance of MPs in all commercial brands is < 700 MP/kg and the particle size range between 5.2 mM and 3.8 μM. The most common types of MPs were identified as fragments, fibers, and pellets. By Fourier-Transform infrared spectroscopy (FT-IR), it was found that the MPs in abundance were made of cellophane (CP), polystyrene (PR), polyamide (PA) and polyarylether (PAR). Further, in vitro toxicity assessment revealed that HEK-293 cells get detached upon treatment with MPs (MIC-75 μg mL^-1) Consequently, the AO/EB dual staining confirmed that the induction and rate of apoptosis were comparatively higher in microplastic treated HEK-293 cells. Taken together, the MPs identified are the origin of anthropogenic derivatives and they exert a lethal effect on human cells, which might be associated with health risk complications in human beings.