Contact lenses are convenient, and new innovations have prioritized comfort, eye health and ease of disposal.
But maybe disposable lenses are too easy.
The vision correcting devices may be adding to pollution, especially of microplastics, in the Earth’s rivers, lakes and oceans, according to new research presented at the 256th National Meeting & Exposition of the American Chemical Society last week.
“I had worn glasses and contact lenses for most of my adult life,” said Dr. Rolf Halden of Arizona State University, who led the study. “But I started to wonder, has anyone done research on what happens to these plastic lenses?”
Halden, doctoral student Charlie Rolsky and graduate research assistant Varun Kelkar – a three-person team that had already been researching microplastics pollution – set out to determine what happens to disposable contact lenses after they’re used.
A huge number, they discovered, are washed down the drain. As much as six to 10 metric tons of plastic contact lenses end up in wastewater in the U.S. alone, the team of researchers said. Because of their weight, most of the lenses sink to the bottom of waterways, where they may be eaten by bottom-feeding marine life.
“We began looking into the U.S. market and conducted a survey of contact lens wearers. We found that 15 to 20 percent of contact wearers are flushing the lenses down the sink or toilet. This is a pretty large number, considering roughly 45 million people in the U.S. alone wear contact lenses,” Rolsky said.
However, there were some difficulties when it came to determining just how much flushed contact lenses are affecting the environment. Unlike other plastic waste, which mainly contains polypropylene, contact lenses are intended to be softer and more breathable for eye health. It’s unclear how much wastewater treatment might affect contacts’ blend of poly(methylmethacrylate), silicones and uoropolymers.
But it may not be good. The team looked at polymers used by five contact manufacturers, then studied samples from wastewater treatment plants. The lenses appear to break down more quickly and easily than some other plastics, the researchers found.
“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,” Kelkar said.
The team admits that more research is needed – but that’s exactly what they’re hoping their research will encourage.
“Ultimately, we hope that manufacturers will conduct more research on how the lenses impact aquatic life and how fast the lenses degrade in a marine environment,” Halden said.
By Kyla Cathey, Earth.com staff writer
Image credit: Charles Rolsky, Arizona State University