What lies beneath: scientists warn of risk to aquatic life from contact lenses

New research presented at a meeting of the American Chemical Society held in Boston, US between 19–23 August has outlined the environmental impact of contact lenses.

A survey carried out by scientists from Arizona State University found that 20% of contact lens wearers flush their contacts down the sink or toilet.

The researchers highlighted that disposable contact lenses are “emerging contaminants of concern” that present a potential physical threat to susceptible aquatic life.

Study author, Dr Rolf Halden, shared his personal motivation for conducting the research.

“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?”

The research team estimated that around 45 million people in the US wear contact lenses, with between six and 10 tonnes of plastic lenses ending up in wastewater each year.

Dr Halden observed that contact lenses tend to be denser than water, meaning that the small pieces of plastic sink and can pose a risk to aquatic life – particularly bottom feeders that may ingest the contacts.

The researchers discovered that when plastics used in contact lenses are exposed to microorganisms present at wastewater treatment facilities, the lenses break down to form micro plastics.

Aquatic animals can mistake micro plastics for food. As plastic is indigestible, this affects the digestive system of marine animals and could ultimately lead to human exposure to plastic contaminants.