Disintegration assessment of a bio-packaging and ecotoxicity evaluation on its aerobic composting products

Compostable bioplastics have been suggested as eco-sustainable alternatives to conventional plastics. This study focused on the disintegration and potential ecotoxicity of an innovative bio-based packaging made of compressed straw and bioplastic film. The packaging disintegrability and the microbiome evolution were evaluated during the aerobic composting process. An organic waste was composted with two different packaging concentrations, 2 % and 6 % w/w, and samplings were collected from the 21st day, every three weeks both to evaluate the hypothesis of accelerated disintegration and to conduct microbiome analysis by Next Generation Sequencing (NGS). Furthermore, at the end of the process, the resulting compost and the bioplastic residues (>2 mm) were tested separately at different concentrations (two for the bioplastic and three for the compost) with a standard artificial soil, to evaluate the toxicological effects on the earthworm Eisenia fetida. Earthworms’ alterations were estimated in terms of fertility, biomass, genotoxic damage with Comet Assay, and impacts on gut microbiome with Next Generation Sequencing. In both theses, the results showed high bioplastic disintegration levels, close to 90 %, already from the first sampling time. The biopolymer residues didn't influence the earthworms' reproductive activity at the two concentrations tested; on the contrary, the earthworms’ fertility was significantly stimulated by the compost at the 20 % dose but not maintained at the 40 % dose. Mortality was observed at 80 %, probably due to the high salinity of the matrix. Similarly, a compost dose-dependent trend was noted in terms of DNA damage. Metagenomics analyses are ongoing.