A World of Plastic

It is hard to imagine our current world without plastic. It surrounds us in various forms, containers, utensils, supermarket bags, furniture and countless other everyday items. However, once its usefulness ends it does not degrade, but instead accumulates as waste. This waste accumulates across the continents and oceans, posing a growing threat to entire ecosystems.

Although the widespread use of plastic began only in the 20th century, the material itself was developed in the 19th century. In 1862, British chemist Alexander Parkes introduced a revolutionary material composed of long chains of cellulose, which he named "Parkesine." Parkesine is often considered as the first form of plastic. The new material exhibited excellent flexibility and durability - the very same qualities that have contributed to the complex and pressing global issue of plastic pollution in recent decades. 

Today, the term "plastic" encompasses a diverse range of materials, all consisting of synthetic polymers, which are essentially long chains composed of identical units. Several types of polymers make up plastic, with many of them derived from the processing of organic materials found in natural oil and gas. The strong bonds between the carbon and hydrogen atoms in these polymer chains make it exceedingly challenging to break down plastic down to its components. Moreover, since plastic is an artificial material, there are practically no naturally occurring bacteria or organisms capable of decomposing it. While plastic does degrade gradually into smaller and smaller particles, it never fully disappears.  

In recent years, there has been a growing realization and awareness of the fact that plastic is becoming increasingly abundant in our world plastic's ubiquity and its environmental impact. The study of plastic's impact on the ecosystem is still an emerging field of research, where scientists from various disciplines collaborate to comprehend its effects on ecosystems such as coral reefs, deserts, rainforests, the ocean floor, and living organisms.

Plastic is growing increasingly abundant in our world. A beach polluted with plastic in Myanmar | Dr Kathryn Berry

High concentration of plastic particles is also found in deep reefs. A blue plastic bag on a sea urchin, in a reef that is 130 meters deep in the Philippines |  Luiz Rocha © California Academy of Sciences

The effects of plastic on marine ecology have only started to come to light in recent years, and it is likely that we have merely scratched the surface of the issue. The findings of a survey conducted across 159 coral reefs indicate that plastic significantly increases the risk of coral diseases. Plastic particles can physically damage coral tissues, rendering them more susceptible to bacterial infections. Among others, the particles tend to attract vibrio bacteria which are known to cause diseases in corals.  

A particular concern arises with marine microplastics, which are tiny plastic particles that are less than 5 micrometers (one thousandth of a millimeter) in size. Their effects don't spare even the smallest of organisms, impeding their growth and development. For example, it was found that sand crabs eggs exhibit less growth and reduced hatching rates when exposed to microplastics.

Shoreline organisms are also affected by plastic particles that are mixed into the sand. Studies on sand crabs along the northwestern shores of the United States reveal that high exposure to and consumption of plastic particles shorten their lifespans. Since many bird species and marine mammals feed on crabs, an increase in plastic concentration can have cascading effects on these organisms, disrupting the entire food chain.

Eggs of sand crabs don’t grow as well in presence of microplastic, and the chances of producing offspring is lower. Sand crabs and plastic particles in a laboratory | Dorothy Horn

And finally, a study showed that even inland freshwater bodies are not immune to  plastic particle contamination - a concerning revelation given that such lakes and pools serve as sources of drinking water for terrestrial animals, as well as for humans. The scientists sampled water from 38 lakes located near human settlements and in more isolated locations. Plastic particles were identified in all lakes, but their concentration and types of plastic varied from one location to another. The most prevalent type of plastic found in the freshwater was polyester, commonly used in fabric production.

Even freshwater habitats on land are not protected from plastic particles. Researcher sampling water from a lake in Kansas, U.S., to test the concentration of plastic particles in them | Ted Harris

Plastic Clouds and Beyond

Spiderwebs were discovered to be an effective and useful tool for capturing particles from the air. One of the webs used in the study | University of Oldenburg/Daniel Schmidt

Plastic And Its Impact On Living Organisms

It remains unclear if and to what extent plastic can harm animals and humans. The term "plastic" encompasses a diverse array of materials, which break down into particles of varying sizes, making it challenging to conduct consistent and repeatable experiments. However, one clear observation that has emerged is that nano-plastic particles, which are exceptionally small particles measuring less than a few billionths of a meter in size, have the capability of penetrating human cells. 

Experiments conducted on cell cultures revealed that at high concentrations, microplastic particles prompted immune cells to react and attack them. This response was consistent across all tested types of plastic. However, numerous unanswered questions persist, including whether these particles accumulate in cells over time, whether they release toxic substances and more. Moreover, the precise pathways through which plastic particles enter our bodies remain unknown. 

Researchers estimate that humans accumulate a substantial concentration of plastic particles through the consumption of animal-based foods. Tests conducted on edible fish, for example, have identified multiple plastic particles. Additionally, experiments involving mice have demonstrated that sufficiently small particles can penetrate our lungs when we breathe through our nose. Researchers have also documented cases in which inhaled plastic particles later reached the placenta of pregnant mice.

One challenge in studying the interaction between plastic particles and living organisms is the difficulty in distinguishing small plastic particles from other tiny particles like dust or sand.  Expensive and sophisticated equipment is required to differentiate between dust particles, grains of sand and plastic. 

Tests conducted on edible fish found multiple plastic particles. A scientist assessing the state of plastic pollution in a coral reef | John Rumney

The Battle Against Plastic

Satellites operated by the National Aeronautics and Space Administration (NASA) have been recruited in the campaign against plastic. Scientists utilize these satellites to monitor the distribution of microplastics from space. Most of the data concerning microplastic locations in the oceans primarily come from observations and local  water samples surveys. These sources provide limited insight into the true quantity and locations of larger concentrations of microplastics. Satellites are employed to measure the water's surface roughness, a metric from which wind speed over the waves can be inferred. The same measurement also indicates the presence of plastic particles floating on the water, as floating waste reduces wave height, thereby reducing water surface roughness.

One potential method to decontaminate the surface of the ocean of plastic particles involves utilizing ballast water - water that ships pump into cells at their base to enhance their stability when they are not carrying cargo. Researchers from India suggest the installation of filters to remove plastic particles from ballast water, subsequently releasing purified water back into the ocean when it is no longer needed. Marine vessels globally use approximately 12 billion tons of ballast water annually. According to scientists' estimates, purifying this volume of water could make a substantial contribution to reducing microplastic levels in the oceans.

Scientists employ NASA satellites to monitor global microplastic distribution from space. A map illustrating the concentrations of plastic particles in the oceans | NASA's Cyclone Global Navigation Satellite System (CYGNSS)