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

Ivan Schwartz
August 21, 2018

His team had already been working on plastic pollution research, and it was a startling wake-up call when they couldn't find studies on what happens to contact lenses after use. "This is a pretty large number, considering roughly 45 million people in the USA alone wear contact lenses". Next the researchers surveyed more than 400 contact lens users about how they dispose of the products, finding that 21 percent discard their lenses down the toilet or sink.

So the researchers tried to replicate a large waste water treatment facility and exposed five polymers used in contact lenses to the kind of microorganisms found in water treatment plants. And with 45 million contact lens wearers in the US alone, that's a lot of contacts ending up in water treatment plants.

The team estimates that anywhere from six to 10 metric tons of plastic lenses end up in wastewater in the USA each year. 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. "[The study researchers'] method of making assumptions and estimations is quite reasonable", she adds.

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 objective than "frivolous" plastics like single-use bags and straws.

The lenses are consequently spread on farmland as sewage sludge, increasing plastic pollution in the environment.

"Then we began looking into the USA market and conducted a survey of contact-lens wearers", said Rolsky, a PhD student who is presenting the work.

Resulting in an estimated 50,000 pounds winding up in sinks and toilets. Halden said the researchers tested 11 brands of contacts and found that they don't degrade during the treatment process but tear into smaller and smaller pieces. The latter scenario is not harmless, says Rolf Halden, director of ASU's Biodesign Center for Environmental Health Engineering and one of the study's authors.

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"It sounds like a very small problem, because the lenses themselves are tiny, but they come by the billions", Halden said.

And there were small changes in the bonds of the plastic polymers after exposure to the microbes. These animals are part of a long food chain. Well, now contact lens manufacturers don't include any information on the packaging about how to dispose of the used product.

Lenses are not generally recycled, although one of the largest manufacturers Bausch + Lomb introduced a programme previous year.

"This is a pretty large number, considering roughly 45 million people in the US alone wear contact lenses", Charlie Rolsky, one of the ASU Ph.D. students who conducted the study, said in a statement.

Throwing Away Your Contact Lenses?

"These are medical devices - you would not expect them to be super-biodegradable", Halden said.

"They are a real improvement in quality of life and are a justified use of plastic, so if we decide as a society that we want to use plastic for these purposes, we should also present the consumer with the chance to get rid of these materials in a responsible fashion".

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