Researchers found that the discarded contact lenses could cause threatening effects to humans and environment.
Contact lens are made by plastic and are often thrown down the drain after its use. Scientists have found that this discarded lenses are contributing to microplastic pollution in waterways. The findings were presented on August 20, 2018 at the 256th National Meeting & Exposition of the American Chemical Society (ACS).
The team of researchers at the Biodesign Institute’s Center for Environmental Health Engineering at Arizona State University (ASU), conducted a survey among contact lens wearers in the U.S. and found that nearly 15 to 20 percent of contact wearers flushed the lenses down the sink or toilet.
The discarded lenses flushed down the drains ultimately end up in wastewater treatment plants. According to the researchers anywhere from six to 10 metric tons of plastic lenses end up in wastewater in the U.S. alone each year. The lenses pose a threat to aquatic life, especially bottom feeders that may ingest the contacts, since the lenses are dense and might sink in water.
Treating contact lenses in wastewater treatment plants is quite challenging as it goes undetected owing to its transparent nature. Also lenses are composed of poly (methylmethacrylate), silicones and fluoropolymers which creates a softer material allowing oxygen to pass through the lens to the eye. So it remains unclear the effects of wastewater treatment on contact lenses.
The team separated the polymers found in contact lenses and exposed them with anaerobic and aerobic microorganisms present at wastewater treatment plants for different length of time and performed Raman spectroscopy to examine them. Noticeable changes were found in the bonds of the contact lenses after long-term treatment with the plant’s microbes. The bonds of the polymer were weakened which ultimately lead to the formation of microplastics.
The microplastics when ingested by aquatic organisms would cause imbalance in ecosystem as these animals are part of a long food chain. Some ultimately reaches to humans, which could lead to unwanted exposures to plastic contaminants and pollutants that stick to the surfaces of the plastics.
The researchers hopes that their work would help the manufacturers in taking steps towards providing a label on the packaging describing how to properly dispose of contact lenses, which is by placing them with other solid waste.