Environmental degradation of plastics containing pro-oxidant additives and their toxicological impact in desert ecosystems

The accumulation of single-use plastic materials poses significant environmental and waste management challenges. Pro-oxidant additive-containing (PAC) plastics have been introduced in many regions to mitigate these impacts. This study examined the abiotic degradation of PAC plastics under accelerated laboratory conditions and in an open-air environment with a hot, dry climate. Residual materials from abiotic degradation were then subjected to aerobic biodegradation in soil, and the final products were evaluated for plant toxicity. Fourier-transform infrared spectroscopy (FT-IR) analysis revealed the formation of acids, ketones, and aldehydes on the polymer surface due to oxidation under accelerated conditions. In open-air exposure, the reduction in weight average molecular weight (Mw) was used to assess degradation. A rapid Mw decrease occurred within the first three months, and after fifteen months, 50% of the samples showed low Mw (<5.0 kDa). The abiotic residues were subsequently mineralized in soil, achieving 15–20% biodegradation after 350 days. Samples not pre-exposed to open-air conditions showed only 5% mineralization, confirming that prior thermal and photo-oxidation enhanced biodegradability. Eco-toxicity tests indicated that the biodegradation products did not affect the growth of the studied plant species. • Some PAC plastics samples were contaminated with heavy metals • PAC plastics abiotically degrade in the open environment with hot climates • The abiotic degradation is depending on the quality of pro-oxidant additives • The temperature in the storage area of PAC plastics should be maintained at 25 °C • Low biodegradation level (15%-20%) was observed after 350 days of incubation in soil • The ecotoxicity on plant has not shown any harmful effects from PAC plastic residues