Plastic pollution: 'Stop flushing contact lenses down the loo'

Lloyd Doyle
August 20, 2018

His team had already been working on plastic pollution research, and it was a startling wake-up call when they couldn't find studies on what happens to contact lenses after use.

The study, presented at an American Chemical Society meeting in Boston, was inspired by personal experience. First, the team surveyed 139 people to determine how contact lenses end up in wastewater.

About 45 million people in the USA alone use contact lenses, according to a survey conducted by the researchers, and between 15 percent and 20 percent of those users said they flush their used lenses down the toilet or sink.

Even if the whole contact lens does not escape through waste water filters, the fragments of them can be unsafe, too, contaminating the environment.

Americans use about 14-billion contact lenses every year. Well, now contact lens manufacturers don't include any information on the packaging about how to dispose of the used product. The team concluded that microbes in the wastewater treatment facility actually altered the surface of the contact lenses, weakening the bonds in the plastic polymers.

This led to smaller plastic...

And those lenses later end up contributing to pollution in oceans, lakes and rivers, stated the study.

Do you flush your contact lenses, rather than put them in the garbage? You might want to stop doing that
Plastic pollution: 'Stop flushing contact lenses down the loo'

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

"This began as an exploratory venture but we have information to support the fragmentation of contact lenses into microplastics within a wastewater treatment plant", said Charles Rolsky, one of the study's authors and a graduate student at ASU.

Earlier research on the individual waste from an average person's disposable contact lenses in the United Kingdom looked more broadly at the environmental footprint of contacts and compared it to waste from soda cans, suggesting that the lens-related waste is relatively small, per person-roughly equivalent to the disposal of 15 cans of Coca Cola per year. "We'd love to have a dialogue [with manufacturers] and establish a solid protocol for consumers to dispose of or even recycle their contact lenses", Rolsky says.

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, researchers said. Further, the plastics used in contact lenses are different from other plastic waste, such as polypropylene, which can be found in everything from auto batteries to textiles.

Graduate research assistant Varun Kelkar said: 'We found there were noticeable changes in the bonds of the contact lenses after long term treatment with the plant's microbes'.

Contact lenses are often made from a mixture of acrylic glass, silicones and fluoropolymers that allows manufacturers to create a softer plastic material which permits oxygen to pass through to the eye.

Some eventually find their way to the food supply, which could lead to people being exposed to plastic contaminants and pollutants that stick to the surfaces. "[The study researchers'] method of making assumptions and estimations is quite reasonable", she adds.

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