The word microplastic has slowly but steadily crept up in scientific literature over the past couple of years. These small and near invisible pieces of plastic have created quite a name for themselves, along with a lot of confusion around what they are and how they may be damaging the environment. Public awareness to help reduce plastic use is an excellent way forward but not all of the information feeding this movement is based on sound evidence. Having just started my PhD on microplastic presence in UK waterways, I am currently dissecting a lot of the evidence around microplastics to try and understand what we know and more importantly what we don’t know.
In this blog, I’ll start by introducing microplastics. In the following post i will describe what we know of land based inputs and their transport pathway into the sea. My final blog will outline what potential hazards they may cause to living organisms and what current studies have shown.
Microplastics can be characterized as any piece of plastic smaller than 5mm. A vast majority of them are therefore invisible to the naked eye. The first type of microplastic that will now often jump up in mind is: microbeads! These are the small and frankly highly unnecessary plastic beads used in exfoliating and personal care products to help scrub off dead skin. They are slowly being banned in countries across the world, and the UK has joined in quite recently with microbead manufacturing to become illegal as of the 1st of January 2018. So, will that be it with microplastics then? Well not really, as microbeads are only a fraction of microplastics out there…
Microplastics also encompass many other very common forms such as:
- Fibres – Many of our clothes are made of synthetic plastic fibres, such as nylon and polyethylene terephthalate (PET), and a single washing cycle can shed up to 700,000 fibres!
- Nurdles – Plastic is manufactured by small pellets that are melted and moulded together to form any desired shape. These pre-production pellets are called nurdles.
- Fragments – This includes any fragment broken down from larger “parent” plastics. Plastic never truly disappears; it only gets smaller and smaller. Many large plastic objects will break down over time due to erosion from wave action, wind and UV light. Common sources of fragments include car tyres & packaging.
Microplastics can also be subdivided into two broad categories:
Primary microplastics include microbeads, nurdles and fibres. These are manufactured as microplastics, that is as particles of 5mm or smaller. They easily pass through sewage treatment plants that do not necessarily have the appropriate sized filters to catch them.
Secondary microplastics are formed because of larger plastics breaking down. UV rays, wind and wave action causes plastic to fragment into millions of smaller pieces. A good example of secondary microplastics are the resulting polystyrene fragments breaking off fish and ship boxes at the beach. These make their way straight into the ocean if not disposed of properly.
In the following blog, I will expand on how microplastics make their journey from production on land to floating in the ocean.