A low-cost method for identifying plastic polymers used for food and beverage packaging

Abstract Mismanaged plastic waste is a global concern, the problems of which are amplified in low- and middle-income countries where resources to support management measures may be limited. Whilst information regarding the composition of plastic waste is valuable for its management, existing methods to identify plastic polymers typically rely on specialist equipment and expertise. In the absence of polymer-specific information, decisions concerning management and policy lack underpinning evidence relating to the nature of plastic waste, its fate(s), and potential for its mitigation. This study presents a novel polymer identification method that is intended for use in settings where resources are limited and that can be used by observers without specialist skills. A framework was developed to identify five commonly used synthetic polymers based on a sequence of simple tests to determine their physical properties. Performance of this identification framework was evaluated by nine observers who conducted 261 tests on plastic food and beverage packaging samples. The sensitivity of identification differed between polymers and formats (rigid or flexible) but was highest for rigid polyethylene terephthalate (97.5%) and flexible low density polyethylene (98.6%); for these polymers, identification sensitivity was similar to laboratory analytical methods. For rigid and flexible polypropylene packaging, identification sensitivity was lower (50%); for rigid high density polyethylene, identification sensitivity was intermediate (72.5%). It is recommended this novel method is not applied as a replacement for analytical determination of polymers when and where the necessary resources are available, but can be applied to positive effect where resources for specialist analysis are not available. By providing insight to the composition of mismanaged plastic waste, the method presented in this study can provide evidence to support measures for its remediation; polymer identification can be achieved using only readily available and inexpensive equipment, and without recourse to specialist expertise.