Microplastics: What are they, how harmful are they?
Since the invention of synthetic plastics, humans have produced more than 8 billion tons of plastic, mostly after WWII, but only less than 10% have been recycled (1). Plastic is everywhere and it is tough to live without it. This is a topic widely talked about and researched. But it brings other related issues that are less talked about. One of them is the impacts of microplastics on our environment and health.
Microplastics are what it sounds like: tiny fragments of plastics, by definition they measure less than 5 millimeters. We can distinguish 2 kinds of microplastics. Primary microplastics are those that were already made at this size, for example, microbeads used in cosmetics. Secondary microbeads are those that come from bigger plastics that got broken down to the micro size over time by natural forces such as weather conditions, etc.
The most common sources of the microplastics are synthetic textiles (35%), tires (28%), city dust (24%), and other sources like plastic bottles and bags, microbeads used in cosmetics, fishing nets, and packaging materials (2). Most primary microplastics are washed down the drain and the water filtration facilities are unable to filter them out because of the small size and so they end up in our water streams, and finally in the oceans.
Once the microplastics are in the water sources and oceans, they start getting into our drinking water and food chain. Many aquatic species confuse them with food and ingest them. We then consume the plastics in the seafood, sea salt, and water. The most commonly found plastics in the human body are polypropylene (PP) and polyethylene terephthalate (PET), both are the main components of water bottles, milk, and juice containers.
A recent study called No Plastic in Nature: Assessing Plastic Ingestion from Nature to People (3) discovered than we might be ingesting around 5 grams of plastic with our food weekly, with regional variations around the globe. The largest source of ingested plastic is through water, both bottled, or tap water.
The long term effects of microplastic on the human organism are under research, but this ingestion likely exposes us to harmful chemicals found in some plastics. These chemicals are linked to health issues like obesity, reproductive issues, or developmental issues in children.
There is enough concern about the microplastics we ingest that President Obama signed the Microbead-Free Waters Act of 2015, which banning plastic microbeads in cosmetics and personal care products (4).
Moreover, microplastics are not biodegradable, so when they enter the environment, they will stay there forever. They might break down into smaller and smaller particles, but they will not degrade into natural elements. There is already evidence that for seabirds microplastics can get stuck in their stomachs and cause their death (5).
More research is needed to identify the exact harmful impacts of microplastics on our health and the environment, but there is a reason to be worried and it is just reasonable to start coming up with better and safer alternatives to synthetic plastics.