Plastic Waste

Additional scientific description

Plastic is a lightweight, hygienic and resistant material which can be moulded in a variety of ways and used in a wide range of applications. Unlike metals, plastics do not rust or corrode. Most plastics do not biodegrade, but instead photodegrade, a process in which exposure to environmental factors, including sunlight, breaks them down into smaller fragments, eventually forming microplastics, which can persist in the environment for long periods. (UNEP, 2018).

The 14th Meeting of the Conference of the Parties to the Basel Convention defined categories of wastes requiring special consideration (European Commission, 2019). This includes:

• Plastic waste, including mixtures of such waste, with the exception of the following: plastic waste that is hazardous waste pursuant to paragraph 1 (a) of Article 18; plastic waste listed below, provided it is destined for recycling in an environmentally sound manner and almost free from contamination and other types of wastes; and plastic waste almost exclusively consisting of one non-halogenated polymer, including but not limited to the following polymers: polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polycarbonates (PC), polyurethane (PUR) and polyethers.
• Plastic waste almost exclusively consisting of one cured resin or condensation product, including but not limited to the following resins: urea formaldehyde resins; phenol formaldehyde resins; melamine formaldehyde resins; epoxy resins; and alkyd resins.

Plastic waste almost exclusively consisting of one of the following fluorinated polymers: perfluoroethylene/ propylene (FEP); perfluoroalkoxy alkanes; tetrafluoroethylene/ perfluoroalkyl vinyl ether (PFA); tetrafluoroethylene/ perfluoromethyl vinyl ether (MFA); polyvinylfluoride (PVF); polyvinylidenefluoride (PVDF); and mixtures of plastic waste, consisting of polyethylene (PE), polypropylene (PP) and/or polyethylene terephthalate (PET), provided they are destined for separate recycling of each material and in an environmentally sound manner and almost free from contamination and other types of wastes. Most plastics are usually a blend of polymers and additives (e.g., stabilisers such as lead stabilisers and cadmium stabilisers; plasticisers such as phthalates; flame retardants such as antimony oxides, phosphatases, brominated flame retardants and medium-chain chlorinated paraffins). The elements most commonly found in plastics are carbon, hydrogen, nitrogen, oxygen, chlorine, fluorine and bromine. Some of these elements are hazardous when uncombined but become inert when incorporated into an organic polymer (UNEP, 2023a, 2023b).

The composition of plastic waste does not only depend on the intrinsic composition of the different plastics included, but also on impurities or contaminants. These impurities may arise from the various applications of the plastic, as well as the processes of waste generation and collection. For instance, plastic food packaging may contain food residues, films used in agriculture may contain high percentages of soil and pesticide, and plastic waste from cables may contain residual metals such as copper or aluminium. These contaminants can complicate the recycling and disposal of plastic waste, as they introduce additional challenges for ensuring environmentally sound management. The presence of these impurities highlights the need for effective separation, cleaning, and sorting technologies to improve recycling efficiency and reduce contamination risks (UNEP, 2018). COVID-19 increased single-use plastic waste, though plastics use fell overall. The lockdowns and decline in economic activity during 2020 reduced plastics use by 2.2% from 2019 levels. However, the increase in the use of protective personal equipment and single-use plastics has exacerbated plastic littering.

Plastic pollution is defined broadly as the negative effects and emissions resulting from the production and consumption of plastic materials and products across their entire life cycle. This definition includes plastic waste that is mismanaged (e.g. open-burned and dumped in uncontrolled dumpsites) and leakage and accumulation of plastic objects and particles that can adversely affect humans and the living and non-living environment (UNEP, 2023b).

Over 13,000 substances have so far been associated with plastics, either known for use in plastic production or detected in plastic materials. Chemicals of concern can be released from plastic along its entire life cycle, during not only the extraction of raw materials, production of polymers and manufacture of plastic products, but also the use of plastic products and at the end of their life, particularly when waste is not properly managed, finding their way to the air, water and soils. Some chemicals can pose significant challenges to technological solutions to plastics recycling and material circularity (UNEP, 2023a).

Sources of plastic waste can also be categorized based on applications (e.g., bottles/caps/lids: 14.9 %, PET bottles: 12.5 %, supermarket bags/retail bags: 9.3 %, food bags: 6.5 %, food containers: 2.1 %, etc.) and origin (e.g., municipal solid waste and agro-industrial waste) (Nayanathara et al., 2024). Waste requires a consideration of local circumstances and of both the intrinsic composition of plastic and potential contamination. The presence of impurities and contaminants in the plastics may influence the options for managing the waste in an environmentally sound manner and should be addressed appropriately. Contaminated plastic wastes may be a major or minor hazard depending on the contaminant (UNEP, 2023a).

Metrics and numeric limits

Globally, the annual production of plastics has doubled, soaring from 234 million tonnes (Mt) in 2000 to 460 Mt in 2019. Plastic waste has more than doubled, from 156 Mt in 2000 to 353 Mt in 2019. After considering losses during recycling, only 9% of plastic waste was ultimately recycled, while 19% was incinerated and almost 50% went to sanitary landfills. The remaining 22% was disposed of in uncontrolled dumpsites, burned in open pits or leaked into the environment. In 2019 alone, 6.1 Mt of plastic waste leaked into rivers, lakes and the ocean. The build-up of plastics in rivers implies that leakage into the ocean will continue for decades to come even if mismanaged plastic waste was significantly reduced. Furthermore, cleaning up these plastics is becoming more difficult and costly as plastics fragment into ever smaller particles (OECD, 2022). Every minute, the equivalent of one garbage truck full of plastic is dumped into the ocean (WE, 2016)