The microplastics are defined according to NOAA (National Oceanic and Atmospheric Administration) as those plastic particles (microspheres or amorphous fragments) that reach minimum dimensions, 5mm in diameter or less.
The definition is simple and clear, but its subsequent characterization and the impact they cause is being the subject of intense debate by the international scientific community.
Characterization according to its origin
Not all of them originate under the same process. Some are synthesized de novopurposely for some specific industrial purpose, while others are the consequence of the degradation chain from another previous product. The former, by being synthesized at will, can be more easily regulated in their production volume, more or less immediately. The latter, being an intermediate product of a degradation system of another previous element, are difficult to control per se.
Primary source microplastics
As already mentioned, these types of particles are produced at will
as part of a industrial process. In general, these are microspheres of polystyrene
(PET), Polypropylene (PP) or polyethylene (PE) that are added to a multitude of cosmetic and cleaning products, generally with an abrasive function. Its specific diameter depends on the final product to which it is going to be added as an ingredient.
Primary source microplastics are present as abrasives or inert thickeners in cosmetic productssuch as scrubs, bath gels, cleansers, deodorants, sunscreens, and toothpaste. In general, small polyethylene spheres have been replacing the use of diatomaceous earth in most of the low-end and mid-range cosmetic brands. These perfectly round, polished, and chemically inert spheres help to exfoliate skin without causing damage or irritation, or generating possible allergies.
Between the Cleaning products to which are added the microplastics as abrasive element there are laundry detergents and cleaning powders. In this case, the particles that are added tend to have a slightly larger diameter than in the previous case, and they do not necessarily have to show a polished surface. Due to this, they present more versatility in their chemical composition, their shape and their surface.
These particles end dumped by tons directly into the sea through sewage (treated or not), since the filtration processes of the treatment plants are not efficient enough to capture and retain particles smaller than 5 mm.
Secondary source microplastics
Unlike the previous case, these plastic microparticles originate from the process of fragmentation Y erosion of plastics of very diverse origin and shape. They are the direct consequence of uncontrolled dumping and massive of plastic garbage that ends up in the sea.
Almost all of these microplastics come from the degradation of different types of packaging Y plastic artifacts subjected to mechanical erosion. Initially, sunlight can have a partial degrading action. Direct sunlight, especially those UV rays, they help to break large pieces of plastic into smaller and smaller pieces.
Then the effect of friction in the water it continues its course, generating each time minor particles by progressive fragmentation Y erosion of its surface.
The wandering movement of these small fragments, produced by the streams oceanic Over the rocky seabed me sandy, ends up generating these plastic microparticles. The effect of swaying in the breaking areas of the waves can also contribute to this to some extent.
The plastic waste dumped into the sea can contribute to generate particles that end up deposited in the marine sediments, or in suspension in water. These particles progressively enter the food chain, coming to stay integrated into food from marine origin that we consume frequently.
Microplastics in the trophic chain of the marine ecosystem
As plastic microparticles are extremely small and capable of being suspended in water, they could be easily integrated into the food chain, although to what extent has not yet been proven. Its form of incorporation would be the direct consumption of suspended particles by plankton, and his integration into tissues of the filter feeders.
Later, the progressive incorporation of these microplastics into the tissues of animals that feed on plankton, such as crustaceans, fish, mammals and marine predators, could take place, which consume each other along the trophic chain. Those plastic microparticles would eventually reach our table integrated into the Sea products that we consume. They could also do it through farm animals that are fed fish meal.
This cycle is currently being object of study by the marine researchers Y environmental chemicals, among many other specialists. So far no worrisome concentrations of these microplastics have been detected in the marine products we consume, but it is an issue that needs immediate attention.
Is decontamination possible?
Since the last decade of the last century, the final fate of plastics has worried technicians and scientists. The dumping of microplastics into the sea through wastewater, improperly treated, and the escape from solid waste due to overflow of landfills, it is an uncontrolled fact in many places. The way to reverse it is reason for intense debate and concern in scientific circles, technicians and of conservation.
This topic is the focus of expert networks of the most prestigious research institutes of the planet, even without concrete solutions. This is due to the chemical stability of most plastics, whose half-life can be several hundred years, or never at all.
The plastic pollution has become a tangible reality that surrounds us and covers us, demanding actions from all to stop its increase. It requires political-economic and social commitments. Also of greater urgent and focused attention of basic and applied research to find an efficient way to recycle it again, in a safe way for the environment. All these actions constitute a great integration challenge.
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