Microplastics, as the name implies, are tiny plastic particles. Officially, they are defined as plastics less than five millimeters (0.2 inches) in diameter—smaller in diameter than the standard pearl used in jewelry. There are two categories of microplastics: primary and secondary.
Primary microplastics are tiny particles designed for commercial use, such as cosmetics, as well as microfibers shed from clothing and other textiles, such as fishing nets. Secondarymicroplastics are particles that result from the breakdown of larger plastic items, such as water bottles. This breakdown is caused by exposure to environmental factors, mainly the sun’s radiation and ocean waves.
The problem with microplastics is that—like plastic items of any size—they do not readily break down into harmless molecules. Plastics can take hundreds or thousands of years to decompose—and in the meantime, wreak havoc on the environment. On beaches, microplastics are visible as tiny multicolored plastic bits in sand. In the oceans, microplastic pollution is often consumed by marine animals.
Some of this environmental pollution is from littering, but much is the result of storms, water runoff, and winds that carry plastic—both intact objects and microplastics—into our oceans. Single-use plastics—plastic items meant to be used just once and then discarded, such as a straw—are the primary source of secondary plastics in the environment.
Microplastics have been detected in marine organisms from plankton to whales, in commercial seafood, and even in drinking water. Alarmingly, standard water treatment facilities cannot remove all traces of microplastics. To further complicate matters, microplastics in the ocean can bind with other harmful chemicals before being ingested by marine organisms.
Scientists are still unsure whether consumed microplastics are harmful to human or animal health—and if so, what specific dangers they may pose. Even so, many countries are taking action to reduce microplastics in the environment. A 2017 United Nations resolution discussed microplastics and the need for regulations to reduce this hazard to our oceans, their wildlife, and human health.
The World’s Plastic Pollution Crisis Explained
Plastic pollution has become one of the most pressing environmental issues, as rapidly increasing production of disposable plastic products overwhelms the world’s ability to deal with them. Plastic pollution is most visible in less-wealthy Asian and African nations, where garbage collection systems are often inefficient or nonexistent. But wealthy nations, especially those with low recycling rates, also have trouble properly collecting discarded plastics. Plastic trash has become so ubiquitous it has prompted efforts to write a global treaty negotiated by the United Nations.
How Did this Happen?
Plastics made from fossil fuels are just over a century old. Production and development of thousands of new plastic products accelerated after World War II to the extent that life without plastics would be unimaginable today. Plastics revolutionized medicine with life-saving devices, made space travel possible, lightened cars and jets—saving fuel and lessening pollution—and saved lives with helmets, incubators, and equipment for clean drinking water.
The conveniences plastics offer, however, led to a throw-away culture that reveals the material’s dark side: Today, single-use plastics account for 40 percent of the plastic produced every year. Many of these products, such as plastic bags and food wrappers, are used for mere minutes to hours, yet they may persist in the environment for hundreds of years.
Plastics by the Numbers
Some key facts:
- Half of all plastics ever manufactured have been made in the last 15 years.
- Production increased exponentially, from 2.3 million tons in 1950 to 448 million tons by 2015. Production is expected to double by 2050.
- Every year, about 8 million tons of plastic waste escapes into the oceans from coastal nations. That’s the equivalent of setting five garbage bags full of trash on every foot of coastline around the world.
- Plastics often contain additives making them stronger, more flexible, and durable. But many of these additives can extend the life of products if they become litter, with some estimates ranging to at least 400 years to break down.
How Plastics Move around the World
Most of the plastic trash in the oceans, Earth’s last sink, flows from land. Trash is also carried to sea by major rivers, which act as conveyor belts, picking up more and more trash as they move downstream. Once at sea, much of the plastic trash remains in coastal waters. But once caught up in ocean currents, it can be transported around the world.
On Henderson Island, an uninhabited atoll in the Pitcairn Group isolated halfway between Chile and New Zealand, scientists found plastic items from Russia, the United States, Europe, South America, Japan, and China. They were carried to the South Pacific by the South Pacific gyre, a circular ocean current.
Once at sea, sunlight, wind, and wave action break down plastic waste into small particles, often less than half a centimer (one-fifth of an inch) across. These so-called microplastics are spread throughout the water column and have been found in every corner of the globe, from Mount Everest, the highest peak, to the Mariana Trench, the deepest trough.
Microplastics are breaking down further into smaller and smaller pieces. Plastic microfibers (or the even smaller nanofibers), meanwhile, have been found in municipal drinking water systems and drifting through the air.
Harm to Wildlife
Millions of animals are killed by plastics every year, from birds to fish to other marine organisms. Nearly 700 species, including endangered ones, are known to have been affected by plastics. Nearly every species of seabird eats plastics.
Most of the deaths to animals are caused by entanglement or starvation. Seals, whales, turtles, and other animals are strangled by abandoned fishing gear or discarded six-pack rings. Microplastics have been found in more than 100 aquatic species, including fish, shrimp, and mussels destined for our dinner plates. In many cases, these tiny bits pass through the digestive system and are expelled without consequence. But plastics have also been found to have blocked digestive tracts or pierced organs, causing death. Stomachs so packed with plastics reduce the urge to eat, causing starvation.
Plastics have been consumed by land-based animals, including elephants, hyenas, zebras, tigers, camels, cattle, and other large mammals, in some cases causing death.
Tests have also confirmed liver and cell damage and disruptions to reproductive systems, prompting some species, such as oysters, to produce fewer eggs. New research shows that larval fish are eating nanofibers in the first days of life, raising new questions about the effects of plastics on fish populations.
Stemming the Plastic Tide
Once in the ocean, it is difficult—if not impossible—to retrieve plastic waste. Mechanical systems, such as Mr. Trash Wheel, a litter interceptor in Maryland’s Baltimore Harbor, can be effective at picking up large pieces of plastic, such as foam cups and food containers, from inland waters. But once plastics break down into microplastics and drift throughout the water column in the open ocean, they are virtually impossible to recover.
The solution is to prevent plastic waste from entering rivers and seas in the first place, many scientists and conservationists—including the National Geographic Society—say. This could be accomplished with improved waste management systems and recycling, better product design that takes into account the short life of disposable packaging, and reduction in manufacturing of unnecessary single-use plastics.
One Bottle at a Time
We have all seen the photos: birds nesting in piles of garbage along the shore, fish fatally caught in discarded netting, and huge mosaics of debris floating in the ocean. Even more alarmingly, what we see in these poignant images is only a portion of the problem. Approximately half of all plastic pollution is submerged below the ocean surface, much of it in the form of microplastics so small that we may never be able to clean them up completely.
To cut through the enormity of the ocean pollution crisis, one approach is to focus on something recognizable within these images of debris. Identify something you personally have used that may have ended up in the ocean—a water bottle perhaps. Find one in an image and ask yourself, how did it get there?
Plastic is a human-made, synthetic material that was first discovered more than one hundred years ago but did not broadly enter the public sphere until the 1950s. While currently a major culprit in ocean pollution, plastics are not inherently bad for humans or the environment. In fact, in a United Nations (UN) report on combatting the negative effects of plastics, the head of the UN Environment Programme Erik Solheim made a point to acknowledge that plastic is in fact a “miracle material.”
“Thanks to plastics, countless lives have been saved in the health sector, the growth of clean energy from wind turbines and solar panels has been greatly facilitated, and safe food storage has been revolutionized,” Solheim wrote in his introduction. Yet plastic bottles are one of the most common items within marine debris. So how did such a promising material become a symbol of human environmental desecration?
Plastic bottles are a single-use plastic, a product designed to be used only once and then discarded. Single-use plastics also include plastic packaging, for example of meats and fresh produce, which accounts for almost half of all plastic pollution. This type of plastic product is distinct from multi-use plastics, which can also pollute the ocean, but tend to amass less frequently due to their multi-use nature.
For example, refillable bottles can store water in a way that does not produce the repeated waste of a single-use plastic water bottle. Refillable bottles can be made of many materials, including plastic, but last much longer than a single-use bottle and can be recycled when they become old or damaged. For both types of bottles, how they are discarded determines their ultimate resting place and whether they become pollutants of the ocean.
A single-use plastic water bottle was manufactured, filled with water, and likely transported to a store, where it sat on a shelf waiting for a thirsty purchaser. Many of us drink out of plastic bottles several times during an average day, week, or month. Once we are finished with it, we have a choice where we leave that bottle:
- Recycling bin: Bottles destined for recycling are unlikely to end up in the ocean, in their current form, unless they are mismanaged or lost in transit to a processing facility. However, due to recent limitations in how recyclables are internationally transferred and accepted for processing, many of these bottles will unfortunately end up in landfills rather than recycling facilities.
- Trash can: These bottles also will not likely end up, in their current form, in the ocean. However, in areas across the globe with poor waste management or a lack of properly sealed landfills, as a bottle breaks down into microplastic particles over time, some particles may seep into the soil and eventually make their way into our waterways, ultimately entering and polluting the ocean.
- Litter: These bottles may very well be carried by wind, storm water, or other processes to sewers, rivers, lakes, and other waterways that may ultimately deposit the bottle in the ocean.
Multi-use plastic bottles face these same pathways at end of their life—but of course this happens much less frequently since they can be used many times.
National Geographic Explorer Heather J. Koldewey works to empower communities around the world to participate in solving the ocean pollution crisis from single-use plastics via incremental individual actions—including a campaign called One Less, which encourages people to stop using single-use plastic water bottles altogether. One Less is currently based in and focused on London, England and its inhabitants, but anyone can make the choice to use one less single-use bottle.
Once in the ocean, a single- or multi-use bottle moves with the wind and ocean currents as it faces the elements. Plastics can take hundreds of years to break down into microplastic, which gives them plenty of time to sail the seas. After a certain amount of time, much of the debris from the coast will have met an oceanic gyre—a large system of rotating currents. The Pacific Garbage Patch, a widely known icon of ocean pollution, is within one of these gyres.
National Geographic Explorer Jenna Romness Jambeck has described the movement of plastics into such ocean gyres. Her work has influenced testimony to U.S. Congress and inspired discussion in the UN regarding policies that may help mitigate the marine debris crisis. She also co-developed an app to encourage public participation in identifying and cleaning up marine debris, including plastics, enabling citizen-science solutions at the grassroots level.
Specifically, Jambeck published research findings in the journal Science that provide details about the amount of plastic that makes its way into the ocean. Jambeck noted in this publication that the quality of waste management within a country substantially influences its contribution to marine pollution. As an immediate action to combat marine pollution, Jambeck and her colleagues suggest that industrialized countries address the growing use of single-use plastics. According to a 2018 UN report, sixty countries have passed such regulations to curb the use of plastic bags and polystyrene foam (commonly called Styrofoam) products.
Hopefully, future government and community solutions to ocean pollution will move toward an end to the crisis. In the meantime, individuals can get involved in citizen-science initiatives like Jambeck’s Marine Debris Tracker app and make smart choices about how to use and dispose of plastics, particularly the single-use items that dominate marine debris.