Flushed contact lenses are big source of microplastic pollution

James Marshall
August 23, 2018

Now, Arizona State University scientists are reporting the first nationwide study that shows consumers, by discarding used lenses down the drain, may be unknowingly contributing to plastic pollution.

"I wondered what happened to these lenses", said Rolf Halden, director of ASU's Biodesign Institute Center for Environmental Health Engineering.

Some 45 million Americans wear contact lenses.

The researchers say they would like the contact lens industry to address this problem by placing labels on their packaging that would describe the proper way to dispose of contact lenses: by placing them into the garbage.

Of about 14 billion contact lenses used in the US every year, the study estimated that up to 50,000 pounds get flushed or otherwise go down the drain, most destined for waste treatment plants. Of the lens wearers, 19 percent admitted to flushing their lenses down the drain or toilet.

The calculation of how many lenses end up in our wastewater plants and habitat hinged on a variety of data sources. The study is segmented by Application/end users Children, Adults, The Elderly and Others, products type like Rigid Toric Contact Lenses, Soft Toric Contact Lenses and Geographies like North America, Europe, Asia-Pacific, Middle East, Africa, Central America and Rest of the World.

A study released by Arizona State University says contact lenses break down into microplastics that enter the marine ecosystem.

After going down the drain lenses float through the wastewater system to sewage treatment plants
After going down the drain lenses float through the wastewater system to sewage treatment plants

These differences make processing contact lenses in wastewater plants a challenge. Microplastics measure under 0.2 inches (5 millimeters) in length - about the size of a sesame seed or smaller - and can wind up in the ocean and Great Lakes, posing a potential threat to aquatic life, according to the National Oceanic and Atmospheric Administration.

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 treatment plants "fragment them into microplastics, which accumulate in sewage sludge". It estimates 14 billion lenses are thrown away each year in the United States, which can then degrade into microplastics and be absorbed into the environment. This is a pretty substantial number given that it is estimated around 45m people in the country use contact lenses, many of which are disposed of daily.

And because they are tiny, it's hard to be sure what happens to them after they go down our drains. Lenses left on the soil could have adverse effects that are yet to be fully understood, Halden said.

The survey conducted by the team included 400 contact lens wearers, and they discovered that between 15 and 20 per cent have flushed their contact lenses down a toilet or a sink in the past.

Contact lens companies often provide no package instructions about where to dispose of lenses, the ASU researchers note.

At present, there is no way to recycle lenses, although one manufacturer - Bausch + Lomb - has recently introduced a recycling programme.

Other reports by Click Lancashire

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