A solid material which contains as an essential ingredient one or more high-molecular-mass polymers and which is formed (shaped) during either manufacture of the polymer or the fabrication into a finished product by heat and/or pressure. Plastics have material properties ranging from hard and brittle to soft and elastic. (Source: Amendment to the annex of the Protocol of 1978 Relating to the International Convention for the Prevention of Pollution from Ships (MARPOL), resolution MEPC.201(62), annex, “Revised MARPOL annex V”, regulation 1.13.)* “Plastic” is a synthetic material or modified natural material, either a polymer or combination of polymers of high molecular mass modified or compounded with additives such as fillers, plasticizers, stabilizers, flame retardants and colourants. There are different definitions of plastic in current international or national documents. For example, according to the International Organization for Standardization (ISO) “plastic is a material which contains as an essential ingredient a high polymer and which, at some stage in its processing into finished products, can be shaped by flow” (ISO, 2013). Other definitions are available, including from MARPOL. (Source: Technical guidelines of Basel Convention for the identification and ESM of plastic wastes and for their disposal (draft updated version of 23 February 2023, UNEP/CHW/PW-SIWG.4/3 1)). *This term and definition was recently included in the glossary of key terms prepared for the work of the intergovernmental negotiating committee to develop an international legally binding instrument on plastic pollution, including in the marine environment under the category 'Terms not used in Environment Assembly resolution 5/14 that may be related to those used in the resolution and that have definitions adopted or endorsed by an intergovernmental process'. See UNEP/PP/INC.1/6.