Contact lenses are made with a combination of poly (methyl methacrylate), silicones and fluoropolymers to create a softer material that allows oxygen to pass through the lens to the eye, unlike polypropylene, that can be found in everything from auto batteries to textiles.
"We began looking into the USA market and conducted a survey of contact lens wearers".
In the second and third stage, the researchers found out that contact lenses weaken when mixed together with microbes present in wastewater.
Researchers tracked them to waste water treatment plants, where they discovered the lenses fall apart but do not degrade. "This leads to smaller plastic particles which would ultimately lead to the formation of microplastics".
According to the study, those lenses later ended up contributing to pollution in oceans, lakes, and rivers.
Researchers could find only one maker, Bausch + Lomb, that is seriously pursuing a contact lens recycling program.
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. Rolsky and his co-authors presented the results Sunday at the annual meeting of the American Chemistry Society.
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Halden assures contact lens users that they should not stop wearing lenses because of this study.
The researchers also tested what happened to contacts in liquids of varying densities, finding that they always sink to the bottom.
'This is a pretty large number, considering roughly 45 million people in the USA alone wear contact lenses'.
But transparent material is hard to observe in wastewater. Lenses left on the soil could have adverse effects that are yet to be fully understood, Halden said.
Aquatic organisms can mistake those microplastics for food and since plastics are indigestible, this dramatically affects the marine animals' digestive system. "So I would be concerned that there would be more of an impact with these microplastics than with the other materials due to their ability to absorb various toxins in the environment, like pesticides and herbicides, and really hyper-concentrate these chemicals and move them into the food chain and up the food chain". This amounts to up to 3.36 billion lenses annually and around 50,000 pounds of plastic. However, its behavior in wastewater and wastewater treatment plants was undocumented.
Some eventually find their way to the food supply, which could lead to people being exposed to plastic contaminants and pollutants that stick to the surfaces. "We found that there were noticeable changes in the bonds of the contact lenses after long-term treatment with the plant's microbes", says Kelkar. By tallying this detritus and studying how it persists in this environment, the study provides the first estimate of the potential burden of these tiny plastics, or microplastics.
According to the researchers, these materials are not routinely screened for environmental monitoring studies, which is why pollution from contact lenses has avoided detection until now.