Key issues for bio-based, biodegradable and compostable plastics governance.

Among global efforts facing plastic pollution, their gradual replacement with alternative materials has gained strength during the last decade. We identified five stakeholders and their respective key participation in the chain of bio-based, biodegradable and compostable plastics (BBCP), which have contributed to several flaws on governance of these materials. The widespread unfamiliarity of the consumers about biodegradability concepts has been leading to misguided purchase decisions and disposal practices, along with possible littering behavior. Simultaneously, the adoption of greenwashing practices by stores and manufacturers contribute to disseminating misguided decisions on plastic consumption. Such issues are further aggravated by the lack of certification standards concerning the impact of littering, including the assessment of persistency and toxicity, also covering those made with biodegradable plastics.". Moreover, even though such alternative polymers were originally conceived as a strategy to minimize plastics pollution, the almost inexistence of specific regulatory frameworks in different political scales may convert them in a relevant part of the problem. Therefore, the governance systems and management strategies need to incorporate BBCP as potentially hazardous waste as they do for conventional plastics.

Are biodegradable plastics an environmental rip off?

While the use of biodegradable polymers is recognized as a global strategy to minimize plastic pollution, the technical standards (TS) used to attest their biodegradability may not be in compliance with most environmental parameters observed aquatic ecosystems. Indeed, through a careful assessment of the TS currently in use, this study evidenced that these guidelines cover only a fraction of the biogeochemical parameters seen in nature and largely disregard those that occur in the deep-sea. Thus, these TS may not be able to ensure the degradation of such polymers in natural environments, where microbial activity, pH, temperature, salinity, UV radiation and pressure are highly variable. This raises environmental concern, since relevant parcel of plastic ends up in the oceans reaching deep zones. Therefore, there is an urgent need to revise these TS, which must consider the actual fate of most plastic debris and include assessments under the challenging conditions found at these types of environment, alongside microplastic formation and ecotoxicology effects. Moreover, the next generation of biodegradability tests must be designed to enable a cost-effective implementation and incorporate accurate analytical techniques to assess polymer transformation. Furthermore, certification should provide information on time scale and degradation rates and, preferably, be globally harmonized.

Commercial plastics claiming biodegradable status: Is this also accurate for marine environments?

Concerns about plastic pollution and global public policies have encouraged consumers to acquire environmentally friendly products. Thus, products made of biodegradable plastics have been preferred by the public, despite their costs. However, greenwashing practices, promising more environmental benefits than the products actually offer, has become frequent. Nevertheless, no studies assessing the occurrence of greenwashing in commercial plastic products sold in large world economies have been performed. The present study aimed to experimentally evaluate alterations in structure and chemical composition of selected plastic products marketed in Canada, USA and Brazil. The aging experiments carried out by seawater immersion for 180 days showed no evidence of degradation in 4 out of the 6 studied samples, despite product claims of biodegradability or 100% degradability status. This finding denotes unequivocal greenwashing practices, even including bags made of polyethylene, an ordinary non-biodegradable polymer. Thus, the inadequate adoption of green marketing is deceiving to consumers and may lead to improper disposal of these materials. These practices are highly counterproductive in view of the global public policies recently adopted to control plastic pollution. Therefore, considering the technologies currently available for identification of polymers, a strict control should be exercised over products that claim biodegradable status.