The ocean is filling with plastic at an alarming rate. Some of that plastic is buoyant and visible, but much of it is too small to see from a boat or a plane. These microplastics are impossible to remove and are capable of causing harm to both human and marine health.
What are Microplastics?
A microplastic is any piece of plastic five milimetres or less in size. Microplastics can start out small, or get that way from environmental degradation. Waves, wind, and sun break larger pieces of plastic apart. Rather than biodegrading, plastic just gets smaller. One large piece becomes millions of tiny microplastics, which are all chemically identical to the original.
Microplastics break down into nanoplastics (fragments less than 100 billionths of a meter). These pieces are so small they are invisible to the naked eye and can enter cells, tissues, and organs. No one knows what effect nanoplastics will have, but we do know they will increase as more plastic ends up in our waterways.
Microplastics in the ocean can’t be cleaned up. It’s difficult to estimate how many plastic fragments are in the ocean. One 2014 study estimated there is anywhere from 15 to 51 trillion plastic particles in the ocean. That number is still growing, and quickly. Almost half of all plastic made was produced in the last 18 years. Our dependence on plastic, especially single-use items, continues to grow. And regardless of how many times we use it, all plastic is here to stay.
Where do they come from?
Some microplastics in the ocean are created there when larger pieces break apart. Some arrive small. Synthetic fibers, such as clothing, bedding, and carpets, shed tiny pieces of plastic over time. They can enter the water system when you wash your clothes or particles take off in the wind. Other small plastics include cigarette filters, straws, and chewing gum (yes – gum is plastic and creates 100,000 tons of pollution each year). They enter waterways because they can’t be recycled and often don’t make it to the trash.
Many makeups, body care products, soaps, toothpastes, and abrasive cleaners contain microbeads. These are plastic pieces no larger than a particle of sand. Since all these products are used with water, it’s not hard to imagine how easily they enter our rivers and oceans. A single bottle of face wash can have hundreds of thousands of plastic particles, and most water treatment facilities are unable to filter them out. As a result, microbead products are a direct threat to marine environments. The United States and Canada have both recently banned the use of microbeads in most products, while many European countries have banned them since the early 2000’s.
Why does it matter?
Scientists have documented over 600 species impacted by plastic marine debris. Some of this debris creates physical constraints that trap animals, such as discarded fishing nets or six-pack rings. The majority of this debris causes harm by ingestion. As plastic debris floats around in the ocean, they pick up algae and odors that mimic the smell of food, attracting marine animals to eat them. Plastics build up in the animal’s digestive system, causing blockages and starvation. They also leach toxins that can stress organ function. Although less is known about these effects on marine health.
Plastic is also good at collecting what are known as PBTs, and toxic chemicals such as DDT that persist in the environment even when they are no longer used. As microplastics float around the ocean, they easily collect PBTs. When marine animals ingest plastic, they ingest PBTs, which bioaccumulate in their tissues. When we eat fish, we also eat most of the toxins they’ve ingested in their lifetime.
When it comes to microplastics in the ocean, we don’t know much yet about how they will affect human health. It’s not hard to see that they are and will continue to be a problem for the ocean that feeds us. That is why we all need to make an effort to phase plastic out of our lives.