Published: Wed, August 22, 2018
Medicine | By Tracy Klein

Plastic contact lenses 'could be served up in the food we eat'

Plastic contact lenses 'could be served up in the food we eat'

"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 with Arizona State, a co-author of the paper. And daily disposables, rather than the ones that people wear for a week or more, are one of the fastest-growing parts of the contact-lens market and more convenient and safe.

Wastewater treatment facilities in the US simply don't do a good enough job of filtering out the tons of contact lenses that are disposed of through the sewer system, according to new research presented Sunday at the American Chemical Society's meeting in Boston. "But I started to wonder, has anyone done research on what happens to these plastic lenses after their useful lifespan is over?"

Lab member Charlie Rolsky, a PhD student, told the conference: "We began looking into the USA market and conducted a survey of 139 people. They contribute a load of at least 20,000 kilograms per year of contact lenses", Halden said. Even so, he and his team still urge contact lens wearers to think about the way they throw out their lenses.

Halden assures contact lens users that they should not stop wearing lenses because of this study. "Put them into solid waste or recycle them", Halden said. "In the bathroom, they can get lost in the sink or go down the toilet".

The study's lead, Rolf Haden, was inspired to research contact lenses' impact on the environment based on his own personal use of them.

Direct observation of what happens to these lenses in a wastewater treatment plant was a challenge for several reasons. Moreover, the plastics used in contact lenses are different from other plastic waste, such as polypropylene, which can be found in all items from textiles to auto batteries.

Along the way, wastewater passes through filters meant to keep out larger bits of waste, but because contact lenses are made from flexible material, they can fold up and get through the filters, The New York Times reported. This creates a clear pathway where macro-and microplastics from contact lenses can enter land ecosystems.

They found that the microbes in waste water weakened the bonds in the plastic polymers, causing them to break down into tiny pieces, which would likely be too small to be screened out and thus would end up in our waterways. "This leads to smaller plastic particles which would ultimately lead to the formation of microplastics", said Kelkar. Some, in the end, find their way to the human food supply, which could result in undesirable human exposures to plastic contaminants and pollutants that adhere to the surfaces of the plastics.

The gathered a team to ask people in Arizona who wear contact lenses how they dispose of the ones they used. The microplastics that are formed when this waste water is treated ends up in the water ways and finally into the food chain they explain.

This article has been republished from materials provided by the American Chemical Society.

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