Original article from Insider

 

• About 15-20% of contact lens wearers flush their used lenses down the sink or toilet.
• That’s up to 3.36 billion lenses flushed per year in the US alone.
• According to a new study, this is having a big impact on the environment.
• They end up in wastewater plants and are broken down into microplastics.
• These swirl around the oceans, and can be mistaken by sea creatures for food, meaning plastic ends up in the food chain — and eaten by humans.

 

About 125 million people use contact lenses worldwide. Not all of them are multi-use, so that’s a lot of contacts — potentially billions — thrown away every year.

 

Some people flush their used daily contacts down the sink or toilet, but according to new research, this is a terrible idea.

The study from Arizona State University, presented at the 256th National Meeting and Exposition of the American Chemical Society in Boston, found that discarding used lenses down the drain is contributing to plastic pollution.

 

The lead author Rolf Halden, the director of the Biodesign Institute’s Center for Environmental Health Engineering at ASU, said he couldn’t find any studies on what happens to contact lenses after they are used and discarded.

 

“I had worn glasses and contact lenses for most of my adult life,” Halden told ASU Now. “But I started to wonder, has anyone done research on what happens to these plastic lenses after their useful lifespan is over?”

 

Halden’s team first conducted a survey of people who wear contact lenses, and examined 13 different brands made from nine different types of plastic polymers.

 

“We found that 15 to 20% of contact-lens wearers are flushing the lenses down the sink or toilet,” said Charles Rolsky, a PhD student who worked on the study.

 

“This is a pretty large number, considering roughly 45 million people in the U.S. alone wear contact lenses, amounting to 1.8–3.36 billion lenses flushed per year, or about 20-23 metric tons of wastewater-borne plastics annually.”

 

Contact lenses typically end up in wastewater-treatment plants, which fragment them into microplastics. In about two pounds of wastewater sludge, there tends to be one pair of contact lenses, the study found. So far, the negative impacts of this are poorly understood, according to Halden.

 

What is clear is that it’s concerning for contact lenses to make their way into aquatic environments, because sea creatures may mistake microplastics for food. Eventually, some of it may make its way up the food chain all the way up to humans, because we are exposed to plastics in seafood.

 

The team also looked at how biodegradable contact lenses are by treating them with the anaerobic and aerobic microorganisms found in wastewater-treatment plants.

 

“Whereas the lenses survived treatment for extended periods of time, we found noticeable changes in the bonds of the contact lenses as a result of exposure to microbes,” said Varun Kelkar, another author of the study.

 

“When the lens plastic loses some of its structural strength, it will break down physically. This leads to smaller plastic particles, which ultimately will lead to the formation of microplastics.”

 

Microplastics are increasingly becoming a burden on the environment, with large amounts of plastic debris making its way around the oceans.

 

The researchers hope by highlighting this problem, contact lens manufacturers will issue safety warnings on their boxes for the most environmentally-friendly way to dispose of lenses.

 

“A desirable long-term outcome would be to create lenses from polymers that are fine-tuned to be inert during use but labile and degradable when escaping into the environment,” said Halden.