Evaluating additive release from conventional and biodegradable mulch films

The rising demand for food and the effects of climate change necessitate improved agricultural practices. Mulching enhances soil conditions and reduces water use, with plastic films often favoured for their durability and cost-effectiveness. However, these films contain additives, which may pose environmental and health risks by leaching into soil and crops. This study evaluated the release of seven phthalates and three other common plasticizers from four types of films: polyethylene (PE), oxo-degradable polyethylene (Oxo-PE), polypropylene (PP), and biodegradable polybutylene adipate terephthalate (PBAT). The additives were extracted using both acetone-hexane mixture and aqueous solutions. The results revealed that PP and Oxo-PE released significantly higher amounts of phthalates (6,17 ± 1,06 mg/kg and 7,40 ± 1,65 mg/kg respectively under static conditions) and acetyl-tributyl-citrate (2,75 × 10^-02 ± 2,21 × 10^-03 mg/kg and 2,37 × 10^-02 ± 2,62 × 10^-03 mg/kg, respectively under static conditions) in aqueous environments compared to PBAT (5,01 × 10^-02 ± 7,73 × 10^-03 and 3,66 × 10^-03 ± 8,47 × 10^-04 phthalates and ATBC respectively, under static conditions) and PE (1,73 × 10^-02 ± 4,91 × 10^-03 mg/kg and 3,40 × 10^-03 ± 1,50 × 10^-03 mg/kg phthalates and ATBC respectively, under static conditions). In contrast, PBAT exhibited the highest release of these compounds when extracted with organic solvents (47,19 ± 4,28 mg/kg and 2,03 ± 0,18 mg/kg respectively). Time-dependent correlation analyses showed a significant positive correlation between exposure time and additive release, particularly for PBAT (r = 0.90, p = 0.0023 for phthalates, r = 0.90, p = 0.0026 for ATBC), and PE (r = 0.96, p = 0.00003 for phthalates, r = 0.82, p = 0.007 for ATBC), highlighting a growing release pattern over time. The findings highlight the need to consider both the immediate and long-term impacts of mulch film contamination in soil. The results also provide insights into the comparative release behaviour of additives from biodegradable and conventional films, necessary for assessing their environmental safety.