High levels of microplastics in commercial salt and industrial salterns in Sri Lanka

This study provides the first analysis and quantification of MPs in salt products in Sri Lanka. Commercial table salt brands, rock salt, lab-grade NaCl and raw salt from three salterns were analysed using microscopy and Fourier transform infrared spectroscopy. All salt samples were contaminated with MPs: in commercial salts products it ranged from 11 to 193 items/kg, rock salts had 64 items/kg and lab grade NaCl had 253 +/- 8.9 items/ kg. The MP levels in salterns varied significantly: Hambantota 3345.7 +/- 311.4 items/kg, Puttalam 272.3 +/- 10.6 items/kg, and Elephant Pass 36.3 +/- 4.5 items/kg. Predominantly, MPs were presented as fibres, followed by fragments. Of the 23 polymer types identified; low-density polyethylene (LDPE; 17%), resin dispersion (15%) and high-density polyethylene (HDPE; 12%) were notable. This study provides the first comparison of MPs in raw salt and commercial salt. This information is important to trace the pollutant sources and then to take steps to eliminate MPs in food products consumed.

Automated summary

This study conducted the first analysis and quantification of microplastics in salt products in Sri Lanka, revealing contamination in all samples. Different salt types had varying levels of microplastics, with predominantly fiber and fragment forms. The study identified key polymer types like low-density polyethylene, resin dispersion, and high-density polyethylene, providing important information for tracing pollution sources and eliminating microplastics in food products.