Microplastics inundate every part of the globe, from the Arctic to the Antarctic.
These tiny bits of plastic – less than 5 millimeters – are in some cases too small to see, but they are spread around the world.
Organic chemical pollutants like phthalates can cling to these microplastics, or leach from them, making the particles more toxic.
Where does the microplastic come from, what does it look like chemically, and where does it end up?
Let’s take a look at the chemistry of ocean microplastic.
What Are Some Sources of Microplastic Pollution in the Ocean?
Microplastics come from many sources, including sewage, beach litter, and storm runoff.
- In one 2017 report, Microplastics in Sewage Sludge: Effects of Treatment, a team led by Ann Marie Mahon, of the National University of Ireland, cites sewage as a source for plastic micro-sized and smaller-sized plastic debris.
- Also in 2017, Jason McDevitt and his co-authors implicate many different sources of ocean microplastic pollution. These sources include sewage, beach litter, storm runoff of plastic dust from street and roads, car tires, accidental spills from industry, ocean-dumping from ships, and the agriculture industry.
- Another 2017 study, by Stephanie Wright and Frank Kelly from Kings College London, cite air-borne micro-plastics cycling from ocean surf to the beach and subsequent air-borne suspensions. These researchers tell us that plastic microfibers originate from laundry items, as well. Incomplete sewage processing allows synthetic fibers from clothing to escape into the biosphere.
Seven Types of Microplastics in the Ocean
According to Plastic as a Persistent Marine Pollutant, by Boris Worm, PhD, et al, there are seven predominant types of plastic that account for 80 percent of plastic use in Europe and around the world.
These seven plastics are commonly used by consumers and in industry. In alphabetical order, here they are:
- Polycarbonate, which we use for eyewear and roofing.
- Polyethylene, which we use in packaging.
- Polyethylene terephthalate, which we use for plastic bottles.
- Polypropylene, which we use for packaging.
- Polystyrene, which we use for insulation and in consumer hot beverage containers.
- Polyurethane, which we use in automobiles and in paint products.
- Polyvinyl chloride, which we use in the construction industry.
Plasticizers Leach Into the Ocean
In the ocean, plasticizers often leach from plastic trash into the water. One of the most extensively studied plasticizers is dibutyl phthalate (DBP). DBP was used in polyvinyl chloride, (PVC) plastics for more than forty years.
While dibutyl phthalate was banned in 2008 as a result of the Consumer Product Safety Improvement Act of 2008, other phthalates are still in use. Although some phthalates are toxic, others are not. The list of potentially non-toxic phthalates include dimethyl phthalate and diethyl phthalate.
Manufacturers use phthalates in nail polish, due to their plasticizing property – they provide a shiny, flexible appearance. Phthalates also occur in children’s toys – giving plastic toy soldiers and girls’ dolls a less rigid stature.
Microplastics: Byproducts of Civilization
Plastics, in general, are the byproducts of our civilization. Pieces of cosmetics and children’s toys do eventually end up in landfills or into sewers where they are not readily destroyed. Instead, since they are less dense than water, the bits of plastic float.
The plastics eventually become a part of the five or six large garbage patches in the world’s oceans – and this is where chemicals such as plasticizers leach out into the water. The mixtures of plastics, micro-plastics, and plasticizers in these garbage patches are potentially toxic to the biosphere.
Pollution sources of plastic and micro-plastic are multiple and widespread, and the plastic we discard undergoes transformations in the environment. It’s easy to let microplastic fragments fall from out-of-sight to out-of-mind. However, at some point, we will no longer have the luxury of using endless amounts of plastic and then forgetting about the eventual impact on the environment.