Microplastics in the Environment and in the Human Body
Concerns About Microplastics
Microplastics are tiny pieces of plastic that are less than five millimetres long. They are created by the degradation of larger items and are also deliberately produced for use in manufacturing. Like much of our waste, they collect in bodies of water when they are created or discarded. Some people are very concerned about the effects of microplastics on aquatic life, and rightly so. There is another area of concern that is worrying researchers, however: the effects of microplastics on humans.
Particles of microplastic have been found in samples of tap water from around the world and in some of the seafood and sea salt that we eat. They are also present in certain cosmetics, toiletries, and toothpaste. They may even be present in the air that we breathe.
Scientists know that microplastic particles are entering our bodies. They also know that the particles transport molecules that are harmful to humans at certain concentrations. They haven’t yet discovered whether the microplastic is affecting our health, however. Answering this question could be urgent. As the particles continue to collect in the environment and enter our bodies, we might be heading for a range of health problems.
Importance and Composition of Plastic
Plastics are abundant today. In many parts of the world, they are ubiquitous. They are very useful in many aspects of our lives, including medical treatments. While it's true that some plastics could be avoided, others are the best material that is currently available for a particular function.
Some researchers are trying to create safer plastics. The creation of a plastic or a plastic substitute that has many applications and is also safe for the environment if it's discarded is a challenge. Nevertheless, the effort is very important. Plastics are so common in our lives that eliminating their use seems impossible. I think that plastic recycling and reuse and the use of safer substitutions whenever possible is vital, however.
Plastic are made of polymers. These are long chains consisting of repeating molecules known as monomers. Polyethylene, polypropylene, and polystyrene are common examples of plastics. Chemicals are added to plastics to improve properties such as flexibility or durability. The additives are released into the environment as a plastic degrades.
What Is a Microplastic?
Determining how much plastic waste enters the ocean each year is a difficult task, but according to the United Nations the amount is at least eight million tons.
How Do Microplastics Form?
Degradation of Plastic Waste
Plastic debris in the ocean slowly breaks down into microplastic particles due to the action of ultraviolet light from the sun, reaction with oxygen, and physical degradation by wave and current action. Fishing gear, buoys, and domestic and industrial waste contribute to the debris.
Fibres From Clothes
Another common source of microplastic in the ocean is clothing made from synthetic fibres. Tiny fibres of polyester and acrylic (both a type of plastic) are shed when clothing is washed. The facilities that treat wastewater are often unable to remove the fibres, allowing them to reach the ocean.
Microplastic is also added directly to the ocean in the form of pellets or granules known as nurdles. Nurdles are widely used by manufacturers to make plastic items. They are about the size of a lentil, very lightweight, and not easily noticed if they escape from where they belong. They enter the ocean either from the ships that are transporting them or from where they are stored on land. Nurdles are mistaken as prey by some marine animals and are eaten.
Microbeads are plastic particles that are about about a millimetre in diameter. They are added to products to increase their abrasive and cleaning ability. They are found in some toothpastes, soaps, facial cleansers, and facial scrubs, for example.
It is estimated that about 80% of marine debris originates as land-based trash and the remaining 20% is attributed to at-sea intentional or accidental disposal or loss of goods and waste.— EPA (Environmental Protection Agency)
Contamination of Foods and Drinks
Microplastics have been found in some of the foods and drinks that we ingest. This may not mean that they are present in these items everywhere in the world, but on the other hand contamination of the items may be widespread. More testing is needed.
Microplastic particles have been found in the tissues of fish and shellfish species that are sold in stores and markets. Sea salt containing microplastic has been found in the United States, the United Kingdom, France, Spain, and China.
In 2017, samples of tap water from different countries were analyzed. 83% of the samples contained plastic fibres. A smaller study in Ireland found microplastic in tap water from that country. In 2014, a pair of scientists found that microplastics were present in all of the twenty-four samples of German beers that they tested. The plastic consisted of grains, fragments, and fibres.
A group of researchers in France has discovered microplastic particles in air. This is worrying, especially if other researchers make the same discovery.
Are Microplastics Becoming a Major Problem?
Leaching and Sorption
It was once thought that although large pieces of plastic debris could be dangerous to aquatic life due to ingestion or entanglement, plastic didn't interact chemically with either sea or fresh water. Scientists now know that this isn't true.
Plastics slowly degrade into microplastic particles. Chemicals added to plastics to improve their properties leach (escape) into the water as this happens. Leached chemicals attach to microplastic particles by a process called sorption.
Some of the leached and sorbed chemicals are listed below. They are thought to be dangerous for us, but this may be true only when they are sufficiently concentrated.
- PCBs (polychlorinated biphenyls) are synthetic chemicals that are no longer made in the United States. They used to be added to plastics and are still present in the environment, however. They can produce a number of harmful health effects and are classified as a probable carcinogen (cancer causer).
- PAHs (polycyclic aromatic hydrocarbons) are persistant chemicals that don't break down easily, like PCBs. They are added to some plastics. They are a possible carcinogen and can also produce other effects.
- Flame retardants, chemicals that act as hormone disrupters, and pesticides are also carried by microplastic particles. Each of these can produce a range of harmful effects, which depend on the identity of the chemical.
Microplastics in the Ocean and the Food Chain
Is Microplastic Dangerous to Humans?
Researchers know that for many of us—and perhaps for most of us—microplastic particles are present in the water that we drink and/or in some of the food that we eat. What they don't yet know is whether the particles or their chemical cargo are hurting us.
There are a number of possible fates for the microplastics that enter our body. Some are listed below. We won't know whether they are true until scientists perform appropriate research.
- Microplastic particles may leave our bodies without being absorbed or without releasing their chemical cargo.
- They may be absorbed but may be quickly broken down or eliminated before they have time to harm us.
- They may be absorbed but then encapsulated so that they don't hurt the body.
- The particles or the chemicals that they carry may not be sufficiently concentrated to hurt us even if they are absorbed.
- The particles or their cargo may be hurting us.
- The particles may not be hurting us yet, but they may do so if they become more concentrated.
Some researchers speculate that microplastics consisting of nanoarticles may be more dangerous for us than ones consisting of larger particles. Nanoparticles are 1 to 100 nm in length. A nanometre (nm) is a billionth of a metre or a millionth of a millimetre. In studies in other areas of chemistry, scientists have discovered that nanoparticles of a substance often behave differently in living things than particles with a larger size. Nanoparticles are small enough to enter cells.
Photo A above shows artificial turf on top of ground rubber tire (GRT) in a football field; most tires are made of synthetic rubber that is actually a type of plastic.
Photo B shows microplastic washed off the field by rain.
A Present Problem and Potential Ones
While we don't need to panic about the existence of microplastics in our body, I think they are a concern. A major problem with microplastics is that we may not be able to avoid their entrance into the body. We have to drink water and breathe air. Eating fish and other types of seafood is not as essential, but the animals are nutritious foods. Adding sea salt to our food is optional, but some types of processed food already contain it.
The increasing number of news reports about the ways in which microplastics are entering our body is troubling. If scientists eventually discover that the microplastic particles are causing health problems—or if the particles eventually do so if their concentration increases—it may be too late to avoid the problems.
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- Glenza, Jessica. "Sea salt around the world is contaminated by plastic, study shows." The Guardian. https://www.theguardian.com/environment/2017/sep/08/sea-salt-around-world-contaminated-by-plastic-studies (accessed September 11, 2017).
- Carrington, Damian. "Plastic fibres found in tap water around the world, study reveals." The Guardian. https://www.theguardian.com/environment/2017/sep/06/plastic-fibres-found-tap-water-around-world-study-reveals (accessed September 11, 2017).
- Taylor & Francis. "How much may German beers be contaminated by microplastics?." ScienceDaily. www.sciencedaily.com/releases/2014/09/140903091949.htm (accessed September 10, 2017).
- "Polychlorinated biphenyls (PCBs) Toxicity." Agency for Toxic Substances and Disease Registry. https://www.atsdr.cdc.gov/csem/csem.asp?csem=30&po=10 (accessed September 11, 2017).
- "Polycyclic Aromatic Hydrocarbons (PAHs)." Tox Town. https://toxtown.nlm.nih.gov/text_version/chemicals.php?id=80 (accessed September 11, 2017).
- "Influence of Various Aqueous Conditions on Additives Releasing From, and Pollutants Sorbing to, Microplastic Debris." NOAA. https://blog.marinedebris.noaa.gov/node/11 (accessed September 11, 2017).
- "UN Declares War on Ocean Plastic." United Nations. http://www.unep.org/newscentre/un-declares-war-ocean-plastic (accessed September 12, 2017).
© 2017 Linda Crampton