95% of U.S. Tap Water Contains Microplastics


Christina Liu | Water Nerd   
**Updated 5/16/2024 to include the latest published research data.

Recent spills of plastic pellets called “nurdles” are shining a new light on microplastic pollution in the environment. Microplastics are found in the air, drinking water, food and consumer products. According to a recent study conducted for the World Wildlife Fund by the University of Newcastle in Australia, the average human is consuming the equivalent of 5 grams of plastic every week, which is approximately the equivalent of a credit card. Scientists have been studying health effects of microplastics on humans, but there’s much that is unknown and uncertain. Some of the things we can do to protect ourselves and the environment include minimizing our use of single-use plastics, and reducing our ingestion of microplastics by using an effective water filter. 

What Are Microplastics?

Microplastics is a general term used to describe plastic particles 5 mm and smaller. Microplastics can come from sources as varied as rubberized plastic from car tires, synthetic fibers shed from fabric, and single use plastic waste broken down into smaller pieces. A more recently recognized source is pre-production plastic beads commonly called “nurdles.” Microplastics in the form of microbeads were used in cosmetics until 2015, when they were banned under the Obama Administration. 

The term “microplastics” is such a broad term that it can be misleading because of the huge diversity of sizes and chemical makeup of the plastics that are found throughout the environment. The World Health Organization says that there is no scientifically-agreed definition of microplastics, as the size definition has limited value, especially with drinking-water, since particles at the upper end of the size range (closer to 5 mm) are unlikely to be found in treated drinking-water. A subset of microplastics <1 µm in length are often referred to as nanoplastics.

Where Does Microplastic Pollution Come From and How Widespread is it?

Textiles are the largest source of microplastic pollution - specifically microfibers that shed from fabrics when washed repeatedly. Tire dust particles formed from car tire abrasion on road are also a large contributor to microplastic pollution in the environment. Microparticles have been found in oceans, lakes, and rivers, due to runoff and other forms of pollution. Single use plastics are another huge source of plastic pollution throughout the world. Single use plastics do not fully decompose, but break down into smaller and smaller particles, forming microplastics. 

A recent article highlights another type of microplastic commonly known as “nurdles,” which is considered to be one of the top three sources of microplastic pollution in the oceans. These lentil-sized pre-production plastic pellets are the building blocks of plastic products. The nurdles are made with many different types of plastics. These plastics can have different densities so may either float or sink, depending on whether it’s in freshwater or salt water. This unfortunately can result in a very range of nurdle contamination areas. Nurdles most disastrously enter the environment when cargo ships carrying these pellets spill their cargo into the ocean.

Microplastics have been discovered in locations as deep as the Mariana Trench, as high up as the Swiss Alps, in Arctic snow and in Antarctic wildlife, in surface water and groundwater Microplastics are found in the air, rain, and even products designed for human consumption including including beer, table salt, a large percentage of seafood, especially shellfish, such as shrimp, oysters, and mussels. Microplastics have also been found in 90% of bottled water.

Effects of Microplastics on Human Health

People are exposed to microplastics through inhalation, ingestion, and dermal contact due to their presence in food, water, air, and consumer products. Microplastics are in the air we breathe, the water we drink, and the food we eat. According to a recent study conducted for the World Wildlife Fund by the University of Newcastle in Australia, the average human is consuming the equivalent of 5 grams of plastic every week, which is approximately the equivalent of a credit card. According to this study, the largest source of plastic ingestion worldwide is through drinking water. The second source of plastic ingestion is from shellfish - specifically: oysters, clams, mussels, and scallops, which are eaten whole after they have lived in water contaminated with microplastics their entire lives.

A comprehensive study reviewed the effects of microplastics in humans. Studies reviewed in this research have suggested that microplastics exposure is implicated in a variety of health issues, including altering metabolism and cellular function, disrupting immunity and inflammatory response, neurotoxicity, and an increased risk of cancer. Laboratory studies just released last month have also detected microplastics in both human blood and in lung tissue. Additional research has demonstrated that there are concerns of not just the chemicals that make up microplastics, but also with the contaminants that are adsorbed onto their surface, especially as there is an amplification of the toxic effects, known as "augmented joint toxicity."

One study just released in March 2024 suggests patients with carotid artery plaque in which microplastics and nanoplastics were detected had a higher risk of a heart attack (myocardial infarction or MI), stroke, or death than those in whom microplastics or nanoplastics were not detected. 

Ingesting microplastics is also of concern. Consuming shellfish and other marine organisms that are eaten whole (with GI tracts intact), such as mussels, scallops, clams, and oysters, may be a major route of microplastics ingestion, as these organisms accumulate and retain microplastics. The toxicity from consuming the shellfish contaminated with microplastics is most likely dependent on size of the animal, chemicals that it’s been exposed to, and the concentration of toxins present. However, many concerns regarding microplastics in humans continue to remain uncertain. As long as the fish and shellfish are properly cleaned, and the stomach/intestines of the creatures are not consumed, current knowledge suggests that the risk to humans through this potential exposure route may be minimal

Effects of Microplastics in the Environment

There is significant concern that the large (and growing) amounts of microplastics in the environment may be adversely affecting wildlife, especially in the oceans. Evidence shows that microplastics are getting ingested by sea creatures, both by mistaking plastic pieces for food, and also through biomagnification and bioamplification effects, where the plastics and contaminants on the surfaces of the particles increasingly accumulate in the bodies of larger and larger animals as they consume smaller animals that contain microplastics. 

Sea life of all sizes are being adversely affected by inadvertently consuming microplastics, from starvation and malnutrition because the microplastics aren’t digested, and remain in their digestive systems, preventing them from consuming actual food. Many sea creatures in the wild are suffering from malnutrition or die from starvation. In addition, issues with reproduction, with studies demonstrating that eggs and larvae exposed to higher levels of microplastics had a lower hatching and viability rate, which can affect survival of the species. 

Spilled nurdles, in particular, have severely affected coastlines and wildlife when they wash up to shore. These pellets are mistaken for food by the wildlife, including birds and fish. In addition, they can break apart, creating much smaller nanoparticles. Nurdles are highly persistent, and can even be considered a type of “forever contaminant,” circulating in ocean currents and washing up on shores for decades. Even more concerning, the plastic pellets have a water repelling surface, which makes them ideally suited to attract many toxic pollutants like a sponge. As a result, scientists say that the nurdle pellets can have a much, much higher concentration of contaminants on the pellet surface than in the water, potentially up to a million times more toxic. In these amounts, bioaccumulation and biomagnification of the toxic pollutants and microplastics is occurring, and may reach levels hazardous to the wildlife and ecology. The full ramifications of microplastic contamination, however, are not yet known and may not be for many years.

What Can I Do?

Scientists around the world are working hard to study the different issues and effects of microplastics. As always, we advocate listening to the science and following guidance based on the data. In the meantime, there are helpful things we can all do to help reduce the pollution in the environment and to protect ourselves and our families:

  1. Reduce your usage of single-use plastics, such as bottled water and plastic containers. Use reusable bottles for drinking water, as well as reusable food containers instead of single-use styrofoam, plastic containers, plastic bags, or wrap. 

  2. Use a filter with a rated pore size small enough to remove most microplastics from water. Granulated carbon filters do not do this, but carbon block filters with a rated pore size (such as 0.2 micron) can effectively exclude most microparticles from your water. 

  3. Clean seafood thoroughly before cooking, especially being sure to remove the mud veins in shrimp. Because scallops, oysters, and mussels have been found to contain the highest microplastic amounts among seafood, eating less of these types of seafood may be advisable as well. 

  4. Avoid beauty and consumer products that use microbeads, to minimize the effects of microplastics and dermal exposure. 

  5. Use less plastic overall, by choosing more sustainable and environmentally friendly materials. For example, use paper tape instead of plastic tape for sealing boxes, and choose environmentally friendly packaging materials (such as compostable, biodegradable, or dissolvable foam packaging), and wear natural fibers -- non-synthetic clothing fabrics such as cotton or bamboo to help reduce the amount of synthetic microfibers entering the water systems from washing and drying the fabric. 

Other Articles You Might Enjoy:
Microplastics in Water: What You Need To Know
5 Things You Need to Know About Bottled Water
Bioaccumulation and Biomagnification of Toxic Chemicals: What You Need To Know
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