Occurrence and health risk assessment of phthalate ester pollution in mulched farmland soil at a national scale, China

Phthalate esters (PAEs), widely used as plasticizers in mulching films, are emerging contaminants of concern in farmland soils. However, systematic data on their pollution characteristics and health risks in long-term mulched soils across China remain limited. In this study, 53 typically mulched farmland soil samples from 29 provinces were analyzed using gas chromatography-tandem mass spectrometry to investigate PAEs occurrence, spatial distribution, drivers, and risks. Method validation showed recoveries of 76.3-111.6 % for 16 PAEs, with limits of detection and quantification ranging from 0.2-3.7 ng/mL and 0.1-0.8 ng/mL, respectively. Results revealed ΣPAE concentrations of 108-2970 μg/kg (mean: 852 μg/kg), with elevated levels in southern/eastern China. Di-isobutyl phthalate and di-butyl phthalate (DBP) showed 100 % detection rates, while DBP dominated contamination (mean: 323 μg/kg). Redundancy analysis identified precipitation and polyethylene microplastic abundance as key drivers. Although non-carcinogenic risks (hazard quotients <1) were low, di(2-ethylhexyl) phthalate posed carcinogenic risks exceeding 10⁻⁴ in 11.3 % of samples. This nationwide assessment highlights the urgency to regulate PAEs emissions from plastic mulch residues and prioritize child health protection in agricultural policies.