Seite - 281 - in Freshwater Microplastics - Emerging Environmental Contaminants?

5 CompetingEconomicModels ImpactMicroplastic Generation The contemporary debate about solutions largely contrasts the circular economy with thecurrent linear economicmodel.Thesecompetingeconomicmodels reveal subjective stakeholder motives, whether it is a fiduciary responsibility to share- holders,anenvironmentalorsocial justicemission,oranentrepreneurialopportunity. These economicmodels influence thedesign andutility of plastic and therefore the abundance and exposure of plastic waste to the environment, thus influencing the formationofmicroplastic. Material Loss Along the Value Chain in the Linear andCircular Economic Models Given themanysourcesofmicroplastic, thedifferent sectors of economy and society producing these and the relatively limited knowledge about them (Table 1), it becomes apparent howdifficult it would be trying to “plug” leaks of microplastics to the environment. Someof the sources could be stopped by effec- tive legislation (e.g., banning microbeads in cosmetic products), education and regulation enforcement (litter laws), and technological advancements (effluent filters, biodegradable polymers). However, in the end it becomes increasingly difficult to mitigate these leak points the further from the source intervention begins. The closest point to the source is thechoiceofpolymerandhowit ismanaged throughout the supplychain and once it becomes waste. Some efforts have included an upfront tax to fund cleanupeffortsormitigateenvironmental impacts,but thoseappear impracticaldue to thediffusionanddifficulty incollectingsmallmicroplastics.Giventhe lowvalue ofmostpostconsumerplasticproductsand lackof recovery incentives, thechances of downstreammitigation are extremely low. Consequently, leaks of microplastics to the terrestrial and ultimately aquatic environment (primary or secondary by input in form of large objects which later degrade intomicroplastics) occur throughout the supplychain, e.g., in formof loss of preproduction pellets, littering, or irresponsible waste management (Fig. 1). Little material remains in the system, and most would not be fit for effective recycling (i.e., reusing) because of contamination or expensive recuperation schemes.Deposition in landfills or energy recovery through incineration therefore appears as the ultimate strategy to remove almost all material from the system, effectively creating a linear economic model. Energy recovery is not a form of recycling and does not break this linearity, because it essentially removes used plastics fromtheeconomicsystemthroughdestruction, converting themintoashes and atmosphericCO2 (Fig. 1). A circular economicmodel on the other hand could address leaks of plastics at all life cycle stages. The reduction of leakage to the environment requires adapta- tion and consensus of all stakeholders, e.g., designing for reuse; discouraging littering, for example, by introducing deposit return schemes; and ensuring a high recycling quota during the waste stage (Fig. 2). Most likely one key to the Microplastic:WhatAre theSolutions? 281