(239h) Compostable Plastics - How Do We Assess Them and Where Should We Use Them?

Compostable plastics present an interesting alternative to traditional fossil based non-degradable plastics, however current assessment techniques do not accurately reflect their potential or environmental impacts. First we discuss the use of life cycle assessment to assess compostable plastics, highlighting gaps in data and knowledge the prevent a full picture being assessed. In particular, databases commonly used for life cycle assessment do not include data for end of life for compostable plastics, instead using a generic “biowaste” data set which includes food waste (and therefore different nutrients and carbon content). Some researchers adapt this base data set to include more accurate CO2 and CH4 emissions from compostable plastics, giving a better picture of global warming potential, however it is only emissions to aid that are considered. We discuss the other impacts that are important, including those on the soil and suggest guideline for life cycle assessment that should be followed when considering compostable plastics. In particular we highlight the need to consider additionality - what extra food waste will be composted (and the nutrients therefore captured) if compostable plastics are used?