Microplastics are very small pieces of plastic commonly defined as less than 5 millimetres (mm) in size. They include nanoplastics, which are generally agreed to be less than 1 micrometre (μm) (GESAMP 2016). Microplastics exist in many forms, including fragments, fibres (referred to as“microfibres”), spheres, films and pellets. Now ubiquitous in the environment, they are present in food, water and air (UNEP and GRID-Arendal 2016; FAO 2017). There are two types of microplastics (Arthur et al. 2009): primary microplastics are manufactured for the purpose of being added to (or used in the production of) other products; secondary microplastics are created by the fragmentation and degradation of macroplastics (i.e. plastic items greater than 5 mm in size).
Most microplastics found in the environment are secondary microplastics. Microplastics generated on land can make their way to the oceans via household drainage, wastewater systems, street drains, poorly managed waste disposal sites, run-off from agricultural soils or transport through the air. Once microplastics enter the marine environment, they are extremely difficult and expensive to remove.
From collection: Drowning in Plastics: Marine Litter and Plastic Waste Vital Graphics