Author: Lindsey Konkel / Source: Science News for Students
If you wear contact lenses, you might not know the best way to discard old ones. Hint: Washing them down the sink or flushing them down the toilet are not the way to go. Yet one in five people who wear contacts do just that. The bad news: The plastic in their lenses can linger, polluting both water and land.
Researchers quantified the problem, this past August, at the American Chemical Society meeting in Boston, Mass. Rolf Halden was one of them. This engineer at Arizona State University in Tempe also described his team’s findings for reporters at a press conference from the meeting.
Halden studies ways to reduce pollution’s effect on the environment. Many people need contact lenses every day for work and play. Until now, he notes, scientists hadn’t studied what happened to these soft plastic disks after use.
But having worn contact lenses for many years, he could relate to the issue. One day, he thought about what happens to all of those disposable lenses after people are done with them. He and his graduate students, Charles Rolsky and Varun Kelkar, designed some tests to find out.
They started by creating an online survey. More than 400 contact lens wearers took part. The questions asked how many disposed of their lenses improperly. About 20 percent — one in five — sent their used contacts down a sink drain or toilet.
Assuming all U.S. contact-lens wearers do that at the same rate, the researchers then calculated how much plastic would be flushed away each year.
Their estimate: 6 to 10 metric tons! That’s about the weight of two to three adult African forest elephants.Contact lenses are a tiny part of the world’s plastic pollution. A total of 8 million metric tons of plastic end up in the world’s oceans each year. But the unique chemistry of the plastic used in contact lenses…
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