Options for a feasible risk assessment of biodegradation of plastics in the open environment

, Weber Miriam, Eich Andreas, Kuhfuß Hanna, Lott Christian.

Biodegradable plastic materials are increasingly being discussed as an alternative for conventional non-biodegradable plastic and as a mitigation strategy against plastic pollution, especially for items with an intentional input (e.g. mulch films, etc.), with a high risk of loss (e.g. fishing devices, etc.) and where loss is intrinsic to use (e.g. abrasion of aquaculture nets, etc.). Regardless of the source of the waste, all this contributes to the accumulation of plastic in the open environment. The question for society is how to deal with biodegradable plastic known to end up in the open environment. We compiled options for biodegradation testing schemes showing several scenarios. They are based on the delicate balance of either limited informative value or increased costs. The testing schemes include the proof of biodegradability in a laboratory test. If this test is successfully completed, the proof for environmental safety shall be provided by at least performing one ecotoxicity test. The advantage of such an approach is its low costs however, the information usable for an environmental risk assessment (ERA) remains minimal. Increased information could come through a proof for environmental safety provided by ecotoxicity testing on several trophic levels and impact on ecosystem level. To assess the range of lifetimes in the environments of interest field and tank tests should be performed and data fueled into LCA and LCIA. The disadvantages are increased costs and that the risk of waste accumulation is not yet categorizeable. In order to increase the usability of such information for risk assessment mathematical modelling for scenarios of ‘no accumulation' is suggested if data quality is sufficient. The higher costs for testing, should be reduced by the development of an economically feasible evaluation scheme with a set of harmonized standard test methods and specifications.

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