Microplastics footprint in Indonesian edible salt: A comparative study across Western, Central, and Eastern regions

Microplastics contamination in food products has raised global concerns, yet nationwide assessments in edible salt (particularly in Indonesia) remain limited. Most prior studies have focused on isolated locations, offering an incomplete understanding of spatial distribution and exposure risk. This study aims to analysis of microplastics abundance, charcateristic, and potential human intake in edible salt samples across Western, Central, and Eastern Indonesia. A total of 45 salt brands (three replicates per brand) were selected based on regional consumer preferences. Microplastics were extracted using a density separation technique, followed by visual screening and polymer identification. The mean microplastics abundance was 221.9 ± 184.0 particles/kg. Microplastics abundance was highest in Western Indonesia (292.0 ± 254.2 particles/kg), followed by Central Indonesia (212.9 ± 131.4 particles/kg) and Eastern Indonesia (160.9 ± 111.1 particles/kg). Overall, fibers (79.44%) and fragments (19.29%) were the dominant microplastics shapes. Fibers predominated across all regions, particularly in Western (85.54%), Central (67.01%), and Eastern Indonesia (84.81%). Small-sized microplastics (<1,000 μm) were most prevalent overall (59.41%). Regionally, small-sized particles dominated in Western (61.80%) and Central Indonesia (63.67%), whereas larger microplastics (>1,000 μm) were more common in Eastern Indonesia (50.55%). Fifteen polymer types were identified, with chlorobutyl (21.15%), polyester fiber (19.87%), and polyisobutylene (19.35%) most prevalent overall. However, polyester fiber (41.51%), ethylene propylene (42.50%), and polyisobutylene (47.62%) dominated in Western, Central, and Eastern Indonesia, respectively. Estimated Daily Intake ranged from 1.11 ± 0.71 to 1.56 ± 0.99 particles/day, depending on region and consumption level, while the corresponding Estimated Annual Intake varied from 404.99 ± 257.80 to 569.41 ± 362.47 particles/year. The predominance of small-sized fibers and fragments may elevate long-term health risks through dietary exposure. These findings underscore the need for stronger monitoring systems, improved salt processing practices, and national regulatory frameworks. The study also establishes a reference point for evaluating chronic microplastics intake through common food items in Indonesia. ENVIRONMENTAL IMPLICATION: This study demonstrates that microplastics contamination occurs in all edible salt samples collected across Indonesia, indicating that both terrestrial and marine environments contribute to its presence in food products. The predominance of fibers and fragments, along with the detection of multiple polymer types, suggest complex contamination pathways linked to human activities. These findings provide essential baseline data for understanding microplastics transfer from environmental sources to food items. Continued monitoring and standardized analytical methods are needed to better assess exposure risks and support evidence-based management of microplastics pollution in marine-derived commodities.