Microplastics in solar salt: baseline contamination assessment from Goa, India

Abstract

Microplastics (MPs) in food pose potential health risks, yet their occurrence in solar salt remains underexplored. However, limited research exists on MP contamination in natural solar salt, particularly in estuarine environments. This study addresses this gap by assessing MP contamination in salt harvested from solar salt pans downstream of the Mandovi estuary, Goa, India. Eight salt samples were collected from the saltpan and analysed using density separation, filtration, and FTIR spectroscopy. MPs were detected in all samples, with concentrations ranging from 64.00 plus-minus 1.89 to 106.67 plus-minus 10.37 particles/100 g (mean: 84.17 plus-minus 14.47 particles/100 g). The majority of MPs were within the 0.1-0.3 mm size range (49.21 percent), predominantly fibres (90.40 percent), and colourless (64.30 percent). Polyethylene (29.2 percent), polyester (20.8 percent), and polypropylene (16.7 percent) were the dominant polymer types. The pollution load index (1.16) and polymer risk index (PRI greater than 1000) indicated a high ecological hazard (Level V). Estimated annual MP intake from salt consumption was 2,457.8 particles per person. These findings provide critical evidence of MP contamination in natural solar salt and underscore the need for targeted mitigation strategies to minimize human exposure.