Updated: Jul 20
What are microplastics?
Microplastics are defined as plastic debris that are less than 5 millimeters in diameter. They pose a serious danger to oceans, and are an undeniable marker of humans’ impact on the Earth’s marine ecosystems. New estimates suggest that 24.4 trillion pieces of microplastics have contaminated the upper ocean, which adds up to about 82,000 to 578,000 tons.
Plastic is widely used in all sorts of products for its durability. However, that durability also makes it incredibly hard to degrade until it is no longer a danger to the environment.
When larger pieces of plastic are discarded irresponsibly, natural processes can cause them to break into smaller and smaller pieces. Moreover, microplastics known as microbeads are sometimes added directly to products like toothpaste and beauty products. Often, the particles are too small to be caught by any filters that might be present.
Microbeads were notably banned from cosmetics and personal care products in the U.S. by the Microbead-Free Waters Act of 2015. However, not all countries have similar regulations.
Another major source of microplastics are microfibers from clothes made of plastic fibers, such as polyester. As clothes are washed, microfibers can be released and enter the wastewater system. Like microbeads, they are also often too small to be caught by treatment plants’ filters.
After they are directly disposed of into the environment or released from treatment plants, microplastics join the environmental waters. If the plastic travels into streams and rivers that feed into the ocean, they will directly contaminate ocean waters.
What threats do microplastics pose?
Perhaps the most important danger posed by ocean microplastics comes from the possibility of animals ingesting them. As plastic particles become smaller, they are easily consumed by animals, whether intentionally or not.
Ingested plastic can have direct health effects on the animal. In the body, they can leach out the toxic chemicals that had been added during production, which can damage organs. In addition, the physical presence of the plastic in the digestive system can cause malnutrition from the animal believing itself to be full. Currently, 386 species of ocean-dwelling fish have been found to ingest microplastics. Of those, 210 are commercially hunted. Naturally, this raises the concern of microplastic contamination in seafood.
Given that microplastics often accumulate in an animal’s body, they can be passed through the food chain. When humans eat seafood, the microplastics present in the animal can then be transferred into the human’s body.
While no direct connection has been made between microplastics and harmful health effects in humans, they may interact with the immune system to cause oxidative stress (which can damage DNA and cause a variety of other issues), as well as travel through the bloodstream to different organs.
How can we reduce microplastic pollution?
Despite the lack of evidence for immediate health dangers to humans, it’s safer both for us and for the health of other animals to take steps against microplastics in oceans. And as more plastic continues to be made, the amount that can enter the oceans will only get higher.
To help reduce microplastic pollution, we can avoid products with microbeads or microfibers made from plastic (a laundry filter can be used to filter out microfibers from clothing). It’s also important to ensure that plastic waste is not disposed of into the environment.