Marine litter, much of which is plastic, is found in marine and coastal habitats throughout the world, washed ashore, floating or accumulating on the seafloor. Significant surface accumulation zones occur in subtropical oceanic gyres and are sometimes also referred to as a “plastic soup” of waste. Recent research also identifies the Mediterranean as an accumulation zone with a plastic particle distribution and density largely equivalent to that found in the oceanic gyres.
The sources are mainly land-based and associated with poor waste management including littering, wastewater and rain drainage management. In European seas a large proportion of the plastic fraction is composed of plastic packaging, predominantly plastic bottles and bags. In general, sources and impacts vary regionally, e.g. in regions where waste management is generally adequate, the proportion of sea-based sources, such as shipping, fishing and aquaculture is higher.
Microplastics (in principle items smaller than 5mm) are of particular concern. Used directly in products, fragmenting from larger pieces, or generated from other sources such as fibres from washing clothes, microplastics are widespread in the marine environment. Their small size facilitates adsorption of toxic substances and increases their potential bioavailability to organisms throughout the food-chain. Their impacts can therefore be disproportionately high relative to the overall tonnage. A recent statement from the European Food Safety Authority (EFSA) reveals that, while there are many data gaps on the impacts of microplastics on human health, experimental evidence indicates that microplastics have the potential to be transferred between trophic levels; small microplastics and nanoplastics may penetrate deeply into organs. European authorities and consumers have become increasingly worried about the transfer of contaminants from the marine environment to sea-food and microplastics are among the “contaminants of emerging concern”.
Microplastics are used either intentionally in products (such as exfoliating components in cosmetics, in detergents, or as industrial blasting abrasives) or generated during the life cycle of products (for example during production of plastic articles (from pellets, powders and flakes), through tyre wear, washing of clothes) and dispersed by the wind or via sewage, rain drainage systems and/or rivers to reach the coastal and marine environment. Microplastics are also generated from fragmentation of larger pieces of plastic waste present on beaches and at sea.
The potential impacts of microplastics on aquatic life, biodiversity and human health, associated with their intentional use in products, have generated a lot of concerns worldwide. Bans on the use of microplastics in specific personal care products are in place in the US, while Canada has recently added microbeads to their list of toxic substances allowing the government to ban their use. Bans are under consideration in Australia, and also in individual EU Member States, including Ireland, France and the United Kingdom.