A new study into the environmental impact of contact lenses has found an unexpected major contributor to the microplastics problem.
The irresponsible disposal of plastic waste has been put firmly in the spotlight of late, and now we are learning about a whole range of polluting products we might not have thought of before.
Among them, it turns out, is contact lenses, according to a new study presented to the American Chemical Society by Arizona State University.
While disposed of in a number of different ways, those who are putting their used lenses down the drain are contributing directly to the spread of microplastics in our water supplies.
The study’s lead, Rolf Haden, was inspired to research contact lenses’ impact on the environment based on his own personal use of them.
His research showed that between 15pc and 26pc of users in the US throw them down the sink or toilet. This is a pretty substantial number given that it is estimated around 45m people in the country use contact lenses, many of which are disposed of daily.
Trying to follow a lens’ journey from the sink to the sea proved to be incredibly tricky given that they are transparent in the water when they arrive to the waste treatment plant.
Not only that, but the plastic used in contact lenses differs from other waste, such as polystyrene, which is one of the most commonly used and recycled plastics.
A real eye-opener
Contact lenses are frequently made with a combination of polymethyl methacrylate, silicones and fluoropolymers to create a softer material that allows oxygen to pass through the lens to the eye.
Taking this further, the team tested five polymers found in contact lenses in baths of anaerobic and aerobic microorganisms in treatment plants for various amounts of time. The findings showed that the microbes actually altered the surface of contact lenses, weakening the bonds in plastic polymers.
Speaking of the findings, Varun Kelkar of the research team said: “When the plastic loses some of its structural strength, it will break down physically. This leads to smaller plastic particles, which would ultimately lead to the formation of microplastics.”
The researchers hope that this first-of-its-kind research will draw attention to the industry to help make users aware of the damage of putting lenses down the sink or toilet.