How do microplastics affect animals?

How pollution affects animals and plants

Microplastics are tiny pieces of plastic that pollute the environment. They are pieces of at least 5 millimeters in diameter, which come mainly from cosmetics, clothing, fishing, industry, sewage treatment plants, car and truck tires or plastic waste that we use in our daily lives (plastic bags, cups, bottles…).

Microplastics are mainly subdivided into two types. We have the primary microplastics, which are manufactured to be used in products. And, on the other hand, there are the secondary microplastics, which are derived from the deterioration of larger plastic waste such as shopping bags, plastic bottles, wrappers, etc.

And not only this but, as fish eat plastic, when they pass into the food chain, in the end we humans also end up eating the microplastics that the fish have previously eaten and have not been able to digest. Hence, as we said at the beginning, we eat 5 grams of plastic a week.

How plastic affects land animals

For those who live on the coast, a simple walk along the beach can give you an idea of how our addiction to plastic has become as bottles, cans, bags, lids and straws (just to name a few) are ever-present.

While the decline of sea turtle populations in the oceans is due to a variety of factors (most involve exploitation by humans), plastic pollution plays a major role.

Fish, along with really any marine mammal that breathes underwater through its gills, are increasingly at risk from microscopic plastic debris. A study by the University of Exeter suggests that it can take animals 6 times longer to get rid of microscopic marine debris than when they ingest it orally.

Of course, plastic pollution profoundly affects fish species, but unlike the other animals on our list, these are animals that are also often consumed by humans, so it can also end up affecting us.

Animals affected by plastic

A study carried out in Mayan homes in the southeast of the country, by Dr. Esperanza Huerta Lwanga, researcher of the Department of Agriculture, Society and Environment of El Colegio de la Frontera Sur (Ecosur), detected the presence of microplastics in the turriculums, or worm excrement, and inside the gizzards of chickens and hens for human consumption.

EH: It is a problem because they are ingested by soil macroinvertebrates. In studies conducted in conjunction with Wageningen University, we have found that soil invertebrates, such as earthworms, after ingesting plastic, lose weight and if plastic concentrations are very high, they die. These organisms are fundamental for maintaining soil fertility and their death affects the health of the soil, where diverse plants grow.

EH: In Mexico it is a big problem, especially in terms of poor waste management, because many people, especially in the southeast of Mexico, burn garbage because there is no good waste collection system.

How garbage affects marine animals

The experiments are carried out in the field, using indicator species and working with indirect methods that avoid the sacrifice of the organisms; fecal samples are analyzed and through them the amount of microplastics they have, their type and the additives they contain are identified.

Microplastics are incorporated into the marine flora and fauna found in the water column and seabed; they are incorporated into the trophic or food chains from the plankton, phytoplankton (plant organisms) and zooplankton (animals) that consume these particles, for example, a sardine that feeds on zooplankton, will be consumed by another fish and this one by another and sooner or later the human being will eat microplastics through that fish.

It has been demonstrated that when a fish consumes a particle of microplastics, after two hours its chemical components are already in its bloodstream and in several days they pass to the fish tissue, that is, in the meat consumed by people.