MANY people rely on contact lenses to improve their vision. But these sight-correcting devices don’t last forever — some are intended for a single day’s use — and they are eventually disposed of in various ways. Now, scientists are reporting that throwing these lenses down the drain at the end of their use could be contributing to microplastic pollution in waterways.
The researchers are presenting their results recently at the 256th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 10,000 presentations on a wide range of science topics.
“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,” says Charlie Rolsky, a Ph.D. student who is presenting the work. Halden, Rolsky and a third member of the team, Varun Kelkar, are at the Biodesign Institute’s Center for Environmental Health Engineering at Arizona State University (ASU). “This is a pretty large number, considering roughly 45 million people in the U.S. alone wear contact lenses.”
Lenses that are washed down the drain ultimately end up in wastewater treatment plants. The team estimates that anywhere from six to ten metric tons of plastic lenses end up in wastewater in the U.S. alone each year. Contacts tend to be denser than water, which means they sink, and this could ultimately pose a threat to aquatic life, especially bottom feeders that may ingest the contacts, Halden says.