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Here’s How Your Contact Lenses May Be Polluting the Ocean

3 minute read

New research suggests that millions of contact lenses may be ending up in U.S. water supplies each year, potentially contributing to ocean pollution.

“If you think of plastic pollution, contact lenses are not the first thing that come to mind,” says Rolf Halden, director of the Biodesign Center for Environmental Health Engineering at Arizona State University. But given the estimated 45 million wearers of contact lenses in the U.S. alone, Halden and postdoctoral student Charlie Rolsky got to thinking: how many millions of people are disposing of these plastics improperly?

The two conducted a survey of about 400 contact wearers and found that roughly 15 to 20% had flushed contacts down a toilet or sink drain at some point. That result suggests that a significant number of lenses are ending up in waste-water treatment plants — a conclusion they confirmed after visiting treatment plants and spying lenses in the water. The results were presented Sunday at the National Meeting & Exposition of the American Chemical Society in Boston.

“We were concerned with what happens to those contact lenses once they’re exposed to the processes in the waste water treatment plant,” Rolsky says.

After analyzing various stages of the process, they found that lenses degraded somewhat during waste-water treatment but did not break down entirely, meaning that small fragments of plastic are being flushed out into the water supplies, potentially endangering marine life.

“From past studies, we know that microplastics are able to absorb contaminants at a much higher level than what’s found in the surrounding environment,” Rolsky says. “That presents threats to that particular organism and anything that feeds on it” — including humans, further up the food chain.

It’s important to keep the findings in perspective; Halden points out that contacts make up a “very, very small fraction” of the plastics that ultimately wind up in the ocean, and serve a far more useful purpose than “frivolous” plastics like single-use bags and straws. Still, the researchers say contact users should be diligent about disposing of their lenses properly, and that manufacturers should make it easier to recycle their products.

“If you use them, just make sure you put them into the solid waste, and not have them enter the sink or toilet,” Halden says. “There’s a lot of plastic still going from our population into the environment, into the ocean, and it ultimately comes back to us and can harm us. Everyone should have an incentive to avoid plastic pollution.”

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Write to Jamie Ducharme at jamie.ducharme@time.com