MICROPLASTIC WHAT ARE?

Our daily life is full of plastic, its versatility, lightness, durability and low cost have contributed to the significant increase in their production in recent decades. These same properties in the case of not being made an efficient and careful management, allows these materials to be transported for long distances across oceans and seas. As a result, the issue of plastics has become a growing problem due to its universal presence, potential toxicity and persistence, tending, therefore, to accumulate in the marine environment from coastal areas to the high sea. The plastics, in the seas and oceans, are continually leachate and fragmented, by mechanical action or by the action of the sunlight into increasingly smaller pieces that can even reach the size of grains of sand or even smaller: the microplástics (smaller than 5 mm).

In recent decades the marine pollution of plastics has been a growing threat to marine life.

Since 1950 the world production of plastics has been increasing. In 2013 were produced around 300 million tonnes of plastic, China being the largest producer in the world (only thermoplastic and polyurethanes) with about 28%, followed by Europe with approximately 19% of world production. The packaging sector is the largest user with approximately 40% according to the group of "others" (household products, furniture, sports, health and safety, etc.) with approximately 22% and the construction industry with approximately 20%. In 2014, the forwarding to landfill was still the first destination of plastic waste for many of the countries of the European Union. Despite the awareness campaigns to reduce the use of plastic, the plastic production continues to grow on the order of 1.5% per year. (Plastics Europe, 2016).

The plastics aggregate more than 20 families of polymers including polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane (PUR), polystyrene (PS) and Polyamide (PA), which represent approximately 90% of the total world production. In addition to the main polymer, plastic contains a series of additives to improve the properties of products such as: ductility, hardness, durability or weather resistance. For some of these additives especially certain plasticisers, there are studies that indicate the effect of endocrine disrupters on animals and humans. Every year, a very significant part of the plastics industry and consumers are released into the environment, it is estimated that approximately 10% of plastics produced ending in the oceans and seas.

In less than a century of existence of plastic debris already represent approximately 60 to 80% of marine litter depending on the location. Once in the environment, macro litter suffer mechanical damage (erosion, abrasion, chemical (photo-oxidation, temperature, corrosion) and biological (degradation by micro-organisms). The fragmentation of the plastic is considered to be an infinite process and which may continue until the molecular level can lead to continuous training of microplastic and nano plastic particles (particles smaller than 1 µm), in the environment.

Has wide acceptance among the scientific community the MACRO LITTER definition as the litter of size greater than 25 mm, the term MICRO LITTER based on the definition of microplastic, such as plastic particles with a size less than 5 mm. The range of dimensions of variables between 5 mm and 25 mm are designated as MESO LITTER.

The composition of micro and macro plastics differ due to differences in the efficiency of degradation and origins of various polymers. Samples of floating litter (litter on the surface of the oceans) are mostly composed of polypropylene, polyethylene and styrofoam (expanded polystyrene), as well as polystyrene (non-expanded), polyvinyl chloride (PVC) and polyester (PET), (Andrady, 2015). This latter is denser than the seawater and sediments at the bottom.

The presence of Plastic and Micro Plastics in the aquatic environment is a matter of concern. There is increasing evidence that the marine organisms at all levels of the food chain ingest plastics and microplastics that this form entering the food chain. The prevention at source is a crucial aspect to face the challenge of pollution caused by plastic.

The microplásticos (MP) can have origin in 2 Sources:

  • Primary MPs (direct), which includes the industrial abrasive for cleaning of ships and aircraft and those used in household cleaning products for personal hygiene (body scrubs, toothpaste, shaving cream, gel for cleaning), cosmetic products and raw materials in the plastics industry, "pellets" (resin pads), powder of resin virgin or recycled;

  • Secondary MPs (via indirect), plastic fragments, which result from the physical degradation, chemical and biological debris of plastic of larger dimensions.

It is also of general knowledge that the most likely sources which contribute to the entry of small pieces of plastic in the ocean are the beaches because the plastic debris left on the beaches quickly suffer degradation by photo-oxidation due to exposure to ultraviolet radiation from the sun and the heat of the sand (Andrady, 2011), In addition, the plastic particles produced on land that go to the sewers are not retained in wastewater treatment, going to stop the water courses, being transported to the sea.