Persistent synthetic materials which may float, sink or remain in suspension and which may interfere with any legitimate use of the sea. (Source: Protocol for the Protection of the South-East Pacific against pollution from land-based sources,1983, Annex 1, A. 7); most marine litter consists of material that degrades slowly, if at all, so a continuous input of large quantities of these items results in a gradual build-up in the marine and coastal environment. (Source: UNEP)