Health risk and ecological risk assessment from microplastic contamination in sea salt : case study in Ban Laem salt field, Phetchaburi, Thailand

Abstract

Microplastics are ubiquitous in all terrestrial and aquatic environments. In this research, microplastic contamination in sea salt produced from traditional and plastic salt fields was studied. Including seawater used as a raw material for producing sea salt in Ban Leam salt fields, Phetchaburi, Thailand. Random samples were collected 3 replicates per point, for a total of 42 samples. 5M NaCl solution was used to separate the density and digest the organic substances using 0.05 M Fe (II) and 30% H2O2. The shape and color of the microplastics were characterized using a 30x magnification microscope. The amount, size, and polymer type of microplastics were examined using the micro-Fourier transform Infrared spectroscopy (µFTIR) The results of the study found microplastic contamination in sea salt produced from traditional salt fields as follows: Salt grains 424 (186-642) particles/kg, Salt flower 415 particles/kg, and sea salt produced from plastic salt field has the following amounts of microplastic contamination: salt grains 273 (145-533) particles/kg, Salt flower 540 particles/kg and seawater 166 (18-456) particles/L. The common microplastic shapes were fragments and fibers. The most common colors were blue and transparent. The size of microplastics found ranges from 16-100 µm, followed by 101-500 µm. Types of microplastic polymers found include polyamide (PA), polyethylene (PE), polypropylene (PP), polyvinyl acetate (PVA), polystyrene (PS), polyvinyl chloride (PVC), high density polyethylene (HDPE). The results of the study also indicate the age group that may be most exposed to microplastics from sea salt consumption was between the ages of 16 -18 years in males, which has an average exposure microplastics of 905.20 particles/person/year. The risk of hazardous substances from microplastics contaminated in sea salt was found at risk level 2. The ecological risk assessment found that the Pollution load index of microplastic concentration in seawater raw material was level I, low toxic (PLI = 2.15), and the potential ecological risk of microplastics concentration in seawater raw material was at the minor level (PER = 14.99). This study points to the level of microplastic contamination that may affect consumers of sea salt. Manufacturers and policymakers can use this information to find ways to reduce microplastic contamination in sea salt.