Microplastics: Ocean Pollution and Environmental Impact

When plastic degrades, it leaves behind tiny particles known as microplastics. These particles enter the water streams and, ultimately, the ocean. While their impact on human life is still under investigation, their effects on marine life and the environment are potentially disastrous.

Plastics is a collective word for low-cost, strong, flexible, and heat-resistant materials. Until the nineteenth century, humans employed naturally occurring plastics—amber, animal horn, resins, and tortoiseshell—to create everyday items such as combs. When these naturally sourced products became scarce, chemists researched alternative products. They found an interested party in the petroleum industry looking to rid themselves of the waste products emerging from gas and oil production. While prototypes appeared in the nineteenth century, the first fully synthetic plastics were developed in the early twentieth century. As the century progressed, plastic found applications in almost all facets of life and witnessed its most significant increase in the decades after the Second World War. In the 1970s, with the introduction of single-use shopping bags and drinking bottles, plastic waste started to dominate landfills and became a problem. Despite attempts to halt plastic production due to its detrimental effect on the environment, the industry is shifting from Europe and the United States to other industrializing nations. Current estimates hold that the manufacture of plastics will double in 2040, meaning that plastics in the ocean will quadruple in 2050. By 2100, there will be nearly fifty times as much plastic in the sea as in 2020.

Plastic is notoriously difficult to recycle. Only by crushing and grinding plastics can one get at the lower-quality fibers, leading to jacket insulation and road fillers that cannot be recycled further. Less than 10 percent of plastics is estimated to be recycled. The more permanent solution to reducing plastic waste is incineration, which releases more carbon and toxins into the air, thus contributing to further pollution. Most of the plastic is, therefore, dumped or placed in landfills.

Unlike natural products, the polymers behind plastic products do not decompose rapidly but slowly degrade into microplastics and, in a more recently employed term, nanoplastics. The difference between these terms is size. As plastics degrade, they become macroplastics, pieces that measure more than 5 millimeters before further disintegrating into microplastics—ranging from less than 5 millimeters to 0.1 micrometers. Nanoplastics refer to elements that are less than 0.1 micrometers and are generally ten times smaller than the smallest particle of clay. Macro-, micro-, and nanoplastics typically enter the ocean through drainage canals and rivers. The fishing industry and its catching tools—fishing lines and nets—also contribute significantly to the presence of plastic. Plastics do not necessarily enter the ocean in their macro variety. Microplastics are used in cosmetics, specifically facial cleaners and exfoliators; they emerge from cigarette butt fibers or are a by-product of tire and brake pad wear.

Plastics affect the ocean environment in obvious and less obvious ways. The role of more oversized plastic items, such as fishing nets, bottle caps, and six-pack rings, is well understood and frequently documented. Fish, turtles, or marine mammals become entangled in the plastic hazard and die slowly and painfully. Similarly, ingested plastics are mistaken for prey and swallowed, causing stomach blockages or decreased volume with equally slow and lethal consequences. The role of micro- and nanoplastics is more nuanced, and scientists are currently uncovering its effects on marine species. While it was first assumed that most plastics would collect in the oceans’ circular currents, known as gyres, and, through chemical and physical breakdown, form a sludge generally referred to as garbage patches, it is now believed that only a tiny fraction of plastics stay on the surface. Micro- and nanoplastics attach themselves to the sticky gel that emerges as a by-product of microbial metabolism and, together with organic matter, slowly descend to the ocean floor. This phenomenon is sometimes called ocean “snow,” not because of its consistency but because of its resemblance. These particles, which only recently include microplastics, form an essential part of the food web linking the ocean’s surfaces with its depths. Once ingested, microplastics can cause reduced stomach content, much like their macro counterparts, leading to malnutrition and eventual death. Laboratory studies have also revealed that microplastics in fish populations can affect growth, immune response, and fertility. In short, the impact of microplastics will increasingly affect the fishing industry and its ability to keep up with the world’s growing population.

Moreover, humans will increasingly absorb microplastics by consuming fish and shellfish, the impact of which is still under investigation. Lab tests on marine life have revealed that the chemicals associated with microplastics impact behavioral patterns. Similar effects could also impact human mental health. Besides fish, plastics also affect the growth and health of coral reefs, which are already under attack from warming waters and ocean acidification. Mangrove forests that grow in the intertidal zones of tropical and subtropical regions also trap increasing amounts of plastics through their elaborate root systems and become a further site for plastic pollution and degradation.

The growing awareness of the increasing problem caused by microplastics in the world’s oceans has led individuals to seek long-term solutions. Removing plastics from the sea is a remote possibility, but it would represent a time- and cost-consuming endeavor. Furthermore, removing the micro- or nanoplastic particles that even escape water filtration systems is complex and almost impossible. Activists and environmental organizations, such as the World Wildlife Fund, urgently urge governments to reduce the production of plastics and their resulting waste as the only current path to reduce the increasing dangers of microplastics. Research into plastic-consuming bacteria—organisms that break down plastic to harvest the carbon—is still in its infancy. Such bioprospecting research may become our only hope to reduce ocean macro-, micro-, and nanoplastics permanently.

FURTHER READING: Buranyi, Stephen. 2023. “‘We Are Just Getting Started’: The Plastic-Eating Bacteria that Could Change the World.” The Guardian. https://www.theguardian.com/environment/2023/sep/28/ plastic-eating-bacteria-enzyme-recycling-waste. Accessed October 21, 2023.

Freinkel, Susan. 2011. Plastic: A Toxic Love Story. Boston: Houghton Mifflin.

Imbler, Sabrina. 2022. “In the Ocean It Is Snowing Microplastics.” New York Times. https://www .nytimes.com/2022/04/03/science/ocean-plastic-animals.html. Accessed October 11, 2023.

World Wildlife Federation. 2022. Impacts of Plastic Pollution in the Oceans on Marine Species, Biodiversity and Ecosystems. Berlin: WWF Germany.