Pollution of the marine environment due to plastic materials is one of the most severe environmental problems humanity has to face in the 21st century. The strategy devised until now to address this issue is mainly based on two pillars: (1) increasing the interception of discarded plastic wastes by waste management systems; and (2) substituting the traditional ‘‘petro-based” polymers with biodegradable ones. Many issues on the overall sustainability of the second option by the waste management system must still be clarified.

Pollution of the marine environment due to plastic materials is one of the most severe environmental problems humanity has to face in the 21st century. It is now clear that, in addition to other deleterious effects like causing the death of endangered species, such as sea mammals and turtles, microplastics originating from plastic debris can easily enter the human food chain. It is also well known that the vast majority of plastics found in the oceans (70–۸۰%) actually originates on land. Plastic waste prevention should stand as a top priority. In fact, in many countries worldwide policies have been implemented to reduce plastic use and, as a consequence, plastic waste. Most of these policies have been directed at reducing the use of plastic carrier bags charging retailers or customers who choose to use them. The first experience in this field was conducted in Denmark (1994) but now many countries over the five major continents are adopting this approach. More recently, several countries (e.g. UK and France) are implementing policies to ban the use of other disposable plastic items, such as straws, plastic cutlery, and stirrers. However, since the above-mentioned policies have proven to be insufficient to solve the problem linked to plastic pollution, additional measures have been devised to address this issue, centred on two main pillars:
Increase the interception of plastic waste by waste management systems in order to avoid its uncontrolled dispersion on land (littering) and consequent transport to the oceans.
Substitute the traditional ‘‘petro-based” polymers with biodegradable ones, based on renewable feedstocks (Luckachan and Pillai, 2011), which are less persistent in the environment (Emadian et al., 2017). While the first option has been extensively studied and the various opportunities linked to the reuse of plastic waste, recycling, energy recovery and final waste disposal in landfills (acting as carbon sinks) have been explored, the second option is more recent and its impact on the global plastic market is still limited. In 2017 the amount of biodegradable plastics produced at the global level was about 880 Gg (European bioplastics, 2018), corresponding to less than 0.3% of the total amount of plastics produced in the same year (320,000 Gg). The EU Directive 2015/720, which entered into force on May 26th, 2015, focused on a very specific and, as already mentioned, important issue concerning the reduction of plastic pollution: the use of lightweight plastic carrier bags. The Directive aims at limiting the annual number of lightweight plastic carrier bags consumed in the EU to a maximum of 90 units per person by the end of 2019 (50% reduction compared to 2010) and to 40 units per person by the end of 2025 (80% reduction compared to 2010). Moreover, the Directive addresses the issue of biodegradable and compostable plastic carrier bags, with special emphasis on their true biodegradability and on the need of proper labelling in order to deliver the correct information to customers.