In a recent report on ‘marine plastic debris and microplastics’ published earlier last month, the UNEP describes the sources and effects of plastics and microplastics in the oceans and outlines potential solutions. With regard to biodegradable plastics, the report states that they are currently not a solution to marine litter.
European Bioplastics (EUBP) agrees and echoes the report’s call for further research and the development of clear standards for biodegradation in the marine environment. EUBP further stresses the importance of improving waste management on land to prevent plastics from entering the oceans in the first place. The UNEP report is a good basis to discuss this topic further with all relevant institutions. Biodegradable plastics can, as the report points out, provide a solution for specific marine applications such as fishing nets, traps, or pots, which are prone to end up in the ocean and can not always be retrieved easily. The largest share of marine litter consists of plastics that originate from a variety of mainly land-based sources, including ineffectively managed landfills, and public littering. In areas where separate biowaste collection exists, compostable biowaste bags can help divert biowaste, including the bags it is collected in, from landfills and thereby reduce the amount of plastic bags entering into the marine environment in the first place.
Biodegradable plastics should not be considered as a solution to the problem of marine litter. Littering should never be promoted or accepted for any kind of waste, neither on land nor at sea, including all varieties of plastics. Instead, the issue needs to be addressed by educative and informative measures to raise awareness for proper and controlled ways of management, disposal, and (organic) recycling. The improvement of waste management on land is an absolute priority in solving the problem of marine litter.
In the light of Europe’s waste hierarchy, recyclability, including organic recyclability, is and has been the main focus of the bioplastics industry rather than biodegradation in marine environments. Most bioplastics are durable bio-based materials that can be mechanically recycled. Those bioplastics that are biodegradable are specifically designed foremost for organic recycling in industrial compost plants. The CEN standard EN 13432 defines packaging that is suitable for industrial composting but makes no claims about other environments, including marine environment. In agriculture, tests specific to soil define biodegradation of e.g. mulch films in soil.
A number of standardization projects on how to measure marine biodegradation are in progress at ISO and ASTM level. However, further research and, eventually, the design of products that biodegrade in marine environment can only help to reduce the impacts of marine litter in the future where efficient waste management is not sufficient enough. But for that to work, ambitious standards and strict guidelines for environmental claims are needed to make better use of the property of biodegradability for plastics in this special context.