Contact lenses flushed down the toilet making plastic pollution worse

CONTACT lenses flushed down the lavatory are worsening plastic pollution and may even end up on our dinner plates, a study has found.

As many as one in five wearers are believed to have disposed of lenses through drainage systems with other solid waste, sometimes after just a single day’s use.

US researchers have shown for the first time how they can get eaten by fish and other marine life and be returned to us on our plates.

The study, presented at an American Chemical Society meeting in Boston, was inspired by personal experience.

Dr Rolf Halden, an environmental health engineer at Arizona State University, said: “I had worn glasses and contact lenses for most of my adult life.

“But I started to wonder, has anyone done research on what happens to these plastic lenses?” His team had already been investigating plastic pollution and it was a startling wake-up call when they could not find any relevant studies. Lab member Charlie Rolsky, a PHD student, told the conference: “We began looking into the US market and conducted a survey of 139 people.

“We found 19 per cent of contact wearers are flushing the lenses down the sink or toilet. This is a pretty large number, considering roughly 45 million people in the US alone wear contact lenses.”

There are 4.2 million contact lens wearers in the UK with nearly all using either daily disposables or frequent replacements.

The team estimates up to 10 metric tons of plastic lenses end up in wastewater in the US alone each year. As they are denser than water they sink and endanger aquatic life, especially bottom feeders that may ingest them, explained Dr Halden.

But transparent material is difficult to observe in wastewater. What is more, contact lenses are different from plastics used in other products, such as polypropylene, found in everything from car batteries to textiles.

They are often made with a combination of poly (methyl methacrylate), silicones and fluoropolymers to create a softer material that allows oxygen to pass through the lens to the eye. So it is unclear how wastewater treatment affects them. In the first study of its kind five polymers found in many contact lenses were scanned after being exposed for varying time to microorganisms in wastewater treatment plants.

Dr Halden added: “Ultimately, we hope manufacturers will conduct more research on how the lenses impact aquatic life and how fast the lenses degrade in a marine environment.”