Studies commissioned by Italian bioplastics manufacturer Novamont have demonstrated that the Mater-Bi family of materials produced by the company will biodegrade in the marine environment.
The studies, coordinated by Francesco Degli Innocenti, head Product Ecology and Environmental Communication at Novamont, covered three areas: intrinsic marine biodegradability (Novamont laboratories), disintegration in the marine environment (Hydra) and the released ecotoxicity in sediments as a result of the biodegradation of fruit / vegetable bags made of Mater-Bi (University of Siena).
The Mater-Bi materials were tested in accordance with the requirements of UNI EN ISO 19679: 2018 (Plastic materials – Determination of aerobic biodegradation of non-fluctuating plastic materials in the interface of sea water / sandy sediment – Method using carbon dioxide analysis).
It was shown that when exposed to marine microorganisms, Mater-Bi behaves in the same way other cellulosic materials do in terms of degree of degradation and timing. Taking paper as the reference material, Mater-Bi achieved levels of degradation that were essentially the same as paper, in a test period of less than one year.
Importantly, it was also demonstrated that the speed at which biodegradation occurs increases as the size of the particles decreases. Hence, Mater-Bi will not release persistent microplastics; particles this size are completely degraded within 20-30 days, as required by the OECD guidelines.
Degradation in the marine environment
These experiments were conducted by Christian Lott, a researcher at Hydra Marine Sciences GmbH, the German marine biology research and documentation institute on Elba.
Compostable fruit and vegetable bags were tested by taking sandy sediments from different coastal areas of Elba (Marina di Campo, Portoferraio, Naregno and Fetovaia) and introducing these into aquariums with sea water in order to simulate the seabed where waste naturally tends to accumulate. The bags were placed in the aquariums and the pace of disintegration monitored. It was demonstrated that it took Mater-Bi fruit / vegetable bags between less than four months up to just over a year, depending on the nature of the sea beds, to disappear completely. Samples of comparable fruit and vegetable bags made from PE remained completely intact.
The ecotoxicity tests conducted by Maria Cristina Fossi and Silvia Casini at the Biomarkers and Plastic Impact laboratory in the Department of Physical Sciences of the Earth and the Environment at the University of Siena, aimed to evaluate the ecotoxicity of Mater-Bi to marine organisms. Biotests were performed on three model species of organisms exposed to extracts of marine sediments inoculated with Mater-Bi or cellulose. The sediments were incubated at 28 ° C and tested after 6 months, when clear signs of degradation of Mater-Bi were visible, and after 12 months, at which point the inoculated samples had completely disappeared.
The model organisms selected for the study were unicellular algae (Dunaliella tertiolecta), sea urchins (Paracentrotus lividus) and sea bass (Dicentrarchus labrax). The unicellular algae and the sea urchin were used to investigate possible effects of growth inhibition and embryotoxicity, while juvenile sea bass specimens were tested to evaluate possible sublethal effects. The inoculated sediments showed no toxic effects in the model organisms exposed in this study. No toxic substances were generated and leached into the environment by the Mater-Bi material during degradation which could cause alterations in the growth of unicellular algae, embryotoxicity in sea urchin and oxidative stress or genotoxicity in sea bass.
All testing was made possible thanks to the pioneering activities of the Open-Bio research consortium chaired by Ortwin Costenoble of the Dutch Standardization Institute NEN and funded by the European Commission, which laid the foundations for the development of marine testing methods and the subsequent standardization.
Yet, according to Francesco Degli Innocenti, even if biodegradable, it is essential not to dispose of waste ‘irresponsibly whether on land or at sea’ as this nevertheless poses a potential ecological risk. “The intrinsic biodegradability of Mater-Bi products represents an ecological risk mitigation factor that must not become a commercial message but a further element of evaluation of the environmental profile of biodegradable products,” he said.
“If we want to tackle the complex environmental and social challenges that we face in a serious and concrete way, we need to think in terms of value rather than volumes, in a logic of circular economy with soil and water quality at its core,” said Catia Bastioli, Novamont CEO. “The regeneration of these precious resources requires minimizing the use of the products and rethinking them throughout the life cycle.”