A Systematic Review of Polyethylene Microplastic Occurrence and Hazard Quotient Via Soil Ingestion in Terrestrial Environments in the Philippines

This systematic review synthesizes recent evidence on the occurrence of polyethylene (PE) microplastics in terrestrial environments in the Philippines and evaluates potential humanexposure through soil ingestion using a screening-level Hazard Quotient (HQ) approach. Following the PRISMA 2020 framework, a total of 32 studies published between 2021 and2026 were analyzed, focusing on soils, road dust, and sediments. Reported PE concentrations ranged from 80 to 600 items/kg, with particle sizes between 20 and 700 µm. Road dustfrom high-traffic areas, markets, and school vicinities consistently exhibited the highest contamination levels, indicating elevated exposure potential in densely populated urbansettings. Estimated soil ingestion rates of 85–160 mg/day produced HQ values ranging from 0.25 to 2.3, suggesting screening-level moderate to high exposure concern in identifiedhotspots. However, these risk estimates remain preliminary due to methodological variability among studies and reliance on secondary exposure assumptions rather than site-specificmeasurements. Overall, the findings highlight the widespread presence of PE microplastics in Philippine terrestrial environments and underscore the need for standardized monitoringmethods, expanded geographic coverage, and strengthened waste management strategies to reduce environmental contamination and associated human health risks.