Contact lenses end up in the ocean endangering sealife

Galtero Lara
Agosto 20, 2018

This new study suggests that in the U.S. at least, around 14 billion lenses are thrown away, amounting to around 200,000kg (441,000lb) of plastic waste every year. The research was presented on Sunday at the American Chemical Society's annual meeting in Boston. First, the team surveyed 139 people to determine how contact lenses end up in wastewater.

The team sifted through wastewater sludge, and found several fragments of contact lenses, which indicated that wastewater processing doesn't just let the lenses through - it also appears to help them break into smaller bits.

By using data from the major contact lens manufacturers about the various types of contacts purchased (daily, biweekly or monthly), the ASU researchers were able to calculate that Americans wear a total of 13.2 to 14.7 billion lenses a year. Alternatively, Bausch & Lomb offers a recycling program for any brand of contact lenses and packaging.

"The plastics may have the capacity of soaking up contaminants, and so the plastic shards. they'll likely be loaded with toxic chemicals, like heavy metals, PCBs [polychlorinated biphenyls] and other things", Halden said.

"If earthworms consume the soil and birds feed on it, then you could see that plastic make the same journey as is done by plastics debris in oceans, they are incorporated by biota that are also part of the human food chain", said Prof Halden. 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.

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Although contact lens pollution is a concern, it is dwarfed by the eight million metric tons of larger plastic that clogs our oceans every year.

"We found that there were noticeable changes in the bonds of the contact lenses after long-term treatment with the plant's microbes", said Varun Kelkar, one of the authors from Arizona State University. "We found that 15 to 20 per cent of contact wearers are flushing the lenses down the sink or toilet", said Charlie Rolsky, a PhD student at ASU.

It's another form of plastic affecting our environment.

The next part of the research was to figure out what happens to those lenses.

To figure out if the lenses biodegrade, the researchers subjected five of the polymers commonly used in contact lenses to anaerobic and aerobic microorganisms typically found in wastewater plants, for different amounts of time. So it is unclear how wastewater treatment affects them. Second, the unusual plastics used in contact lenses - a combination of poly (methylmethacrylate), silicones and fluoropolymers to create a soft material that allows oxygen to pass through the lens to the eye - are not routinely screened for environmental monitoring studies. Halden mentions, "Ultimately, we hope that manufacturers will conduct more research on how the lenses impact aquatic life and how fast the lenses degrade in a marine environment". ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.

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