Misleading Claims and Misuse of Standards Continues to Proliferate in the Nascent BioPlastics Industry Space

Article contributed by Ramani Narayan University Distinguished Professor Michigan State University Department of Chemical Engineering & Materials Science Chairman of ASTM Committee D20.96 on Environmentally Degradable Plastics & Biobased Products Chairman of ISO/TC 61(Plastics) SC1 (Terminology) and US expert to TC 61/SC5/WG22 on biodegradable plastics Biodegradation takes place when microorganisms utilize carbon substrates to extract chemical energy that drives their life processes. The carbon substrates become ‘food’ which microorganisms use to sustain themselves. For this to occur, the carbon substrate needs to be transported inside the cell. Molecular weight is an important but not only criterion for transport across cell membrane. Factors like hydrophobic-hydrophilic balance, molecular and structural features also govern transport across the cell membrane. Under aerobic conditions, the carbon is biologically oxidized to CO2 inside the cell releasing energy that is harnessed by the microorganisms for its life processes. Under anaerobic conditions, CO2+CH4 are produced. Thus, a measure of the rate and amount of CO2 or CO2+CH4 evolved as a function of total carbon input to the process is a direct measure of the amount of carbon substrate being utilized by the microorganism (percent biodegradation). This is fundamental, basic biology and biochemistry taught in freshman classes and can be found in any biochemistry textbook. This forms the basis for various National (ASTM, EN, OECD) and international (ISO) standards for measuring biodegradability or microbial utilization of chemicals, and biodegradable plastics [1,2].