Non-phthalate plastic additives and related contaminants in greenhouse and open-field cropland soils of southeastern Spain: Occurrence, distribution and screening-level risk

Plastic additives leach from agricultural plastics into cropland soils, yet the non-phthalate plastic additives (NPPAs) increasingly used as replacements for regulated phthalates remain poorly monitored, particularly in soils. In this study, 28 NPPAs were screened in cropland soils from southeastern Spain (48 sites, 96 samples) by gas and liquid chromatography, both coupled to quadrupole-Orbitrap high-resolution mass spectrometry, comparing intensively managed greenhouse soils with extensively managed open-field soils. Ten out of the 28 targeted NPPAs were detected and identified; total concentrations (∑NPPA) ranged from 32.7 to 444,199.4 µg/kg (geometric mean: 1,629.4 µg/kg) and were about ten-fold higher in greenhouse than in open-field soils (median 1,470.2 vs. 148.1 µg/kg; p = 1.4 × 10 -5 ). Triacetin showed the highest detection frequency (88.5%), followed by acetyl tributyl citrate (67.7%). Complementary non-targeted analysis revealed additional compounds identified at varying confidence levels (Schymanski Levels 1–2), including phthalates, other NPPAs, and various anthropogenic contaminants, underscoring the chemical complexity of cropland soils. A screening-level health-risk assessment indicated that hazard quotients (HQs) for triacetin exceeded unity in both adults (up to 2.1) and toddlers (up to 1.6), driven by the dietary pathway (soil-to-plant), while its predicted rat LD 50 value (4808 mg/kg) indicated higher acute toxicity than that of regulated phthalates. These findings show that the substitution of phthalates by NPPAs shifts rather than removes the chemical burden entering agroecosystems, and that NPPAs warrant inclusion in soil-monitoring programs.