More than three million people in the UK wear contact lenses, says the research news hub Science Daily. And wearers must be wreaking havoc on the environment, judging by new American research which shows that one in five users flushes old lenses down the drain without giving it a thought.
‘I had worn glasses and contact lenses for most of my adult life,’ says Arizona State University (ASU) environmentalist Rolf Halden – the driving force behind the report. ‘But I started to wonder, has anyone done research on what happens to these plastic lenses?’
ASU biology PhD student Charlie Rolsky explains the research project’s origins: ‘I think this was one of many interesting brainstorming sessions that we’ve had in Rolf’s office where we’ve just been spit-balling ideas back and forth. And one day Rolf had a particularly bad time with one of his contacts, because he leaned back in his chair and said, “You know, I wonder what happens to these things? They’re so flimsy.”’
Previously, health engineer Halden and his team had worked on plastic pollution research. When it proved impossible to find any studies on the fate of contact lenses after use, everyone was stunned. The realisation served as a wake-up call and an incentive to pursue research, according to Halden, who considers lenses a surprisingly grave ecological threat.
The reason is that wastewater treatment facilities in the US perform poorly at filtering out the tide of contact lenses dumped into the sewer system. The ASU team found that contact lenses are so flexible that they glide through the treatment plant barriers meant to block non-biological waste. Treatment facility workers the team interviewed confirmed seeing lenses bobbing in wastewater.
‘It sounds like a rather small problem, because the lenses themselves are tiny, but they come by the billions and they are packaged also in polypropylene containers that have aluminium lids,’ says Halden.
‘So we did the math on the quantities of mass that flow through the wastewater treatment plant and up on soils and also the material that in principle could be recovered through recycling. And what we find is that there’s billions of lenses ending up in US waste water every year.’
That translates as up to 20% of wearers flushing lenses down the sink or toilet – a lot given that 45 million people in the US alone wear contact lenses. In total, Halden says the lenses cause an annual environmental burden of at least 20,000 kilograms. Add to that the 13,000 metric tons of the polymer polypropylene waste stream generated by blister packaging. The packs are the equivalent of 400 million toothbrushes, and their aluminium lids equate to about 90 million aluminium cans, Halden says.
A growing problem
But the problem only looks set to expand because use of soft lenses especially has ratcheted up over the last decade, spurred by the increasing comfort that flows from a smoother fit with the cornea. In tandem, the number of wearers of aggressively unsustainable, mayfly-like daily disposable lenses is rising, according to the ASU team.
Paradoxically, contact lenses of all varieties have a habit of hanging around, despite their inherent fragility. The bendy hydrogel structures designed with eye oxygenation rather than the environment in mind fragment easily but persist.
‘They don’t degrade. They don’t attenuate. But they become smaller, and so they create what we know as micro-plastic pollution which is contaminating the oceans,’ Halden says.
Micro-plastics are plastic particles less than 0.2 inches or 5 millimetres in diameter – the length of an average red ant. A gnawing presence, the tiny particles have a detrimental effect on wildlife. Aquatic organisms called bottom feeders that live amid sewer sludge mistake them for food. The indigestible jagged snacks damage the bottom feeders’ digestive system, doubtless giving them the bellyache from hell.
Worse, because the minuscule creatures are part of a sprawling food chain, in time some infiltrate the human supply. The potential result is unwelcome human exposure to the suspect particles and the pollutants stuck to them.
Plastic lenses are essentially indestructible but break down into smaller and smaller pieces that are ingested
Yet hardly any contact lens materials are recycled. Halden’s team identified just one manufacturer that operates a take-back programme: the American eye health products firm Bausch + Lomb, runs the One-By-One programme in the United States, Australia and the Netherlands. Bausch + Lomb’s corporate communications chief, Kristy Marks, says that to date the US programme has recycled more than four million used contact lenses, blister packs and top foil. Since launching in November 2016, the program has saved more than 29,000 pounds of waste, Marks says.
Home truths
Meanwhile, Britain already has a severe micro-plastics problem of plague proportions. In fact, one British river has the world’s worst recorded micro-plastic pollution, according to a University of Manchester study that surfaced in March. The site is the River Tame at Denton in Greater Manchester.
The Tame has over half a million – 517,000 particles – per square metre. The level is far higher than at the Incheon-Kyeonggi beaches in South Korea or the Pearl River Estuary in Hong Kong.
Jamie Woodward, professor of physical geography at the Department of Geography, said the results were likely to be the tip of the iceberg. Woodward added that had the research been conducted in South East England or the West Midlands, it would have yielded similar results.
‘We’re shining a light on a huge problem that, until now, has been under the radar. We found micro-plastics everywhere, even in streams high in the hills. Wherever you find people you find plastic. We found we had the worst levels in the world, some of which were extraordinarily high. The River Tame is a global hotspot for micro-plastics,’ Woodward said in a report published in The Daily Telegraph.
In a report for The Lancet, analyst Ashley Cooper states that the maritime plastic contagion is well-documented and has spawned policies designed to curb the creation and use of plastic bottles and bags and boost recycling.
‘However, a key problem with plastics is that they are essentially indestructible; rather than being biodegraded, they break down into smaller and smaller pieces, eventually becoming microscopic fragments. We should no longer just be concerned with large plastic items clogging up oceans and waterways, but also more attention needs to be paid to these tiny fragments and their effects on planetary health,’ Cooper says.
The effect on humans
Oddly, there is little proof that micro-plastics are bad for human health. It just seems obvious. Indirect corroboration comes from a 2013 study into those earthworms of the sea, lugworms. The study, conducted by University of Exeter bio-science expert Stephanie Wright found that if ocean sediments are badly tainted by micro-plastics, marine lugworms eat less and their energy levels suffer.
As a result, the worms’ ability to engineer sediments was eroded. More remarkably, it caused mortality. Basically, with a little help from contained flame retardant, it killed them, suggesting that micro-plastics cannot be good for people either.
Halden’s solution to the plastic infestation is the proposed manufacture of regular contact lens alternatives made from a renewable resource rather than fossil fuel. That theoretical resource would degrade if it escaped into the environment after a given period – not instantaneously but within a reasonable time span, he says.
‘We must ensure that the plastic products we produce today last for hundreds of thousands of years,’ he adds, observing that sustainable development is afoot.
‘I think the situation now is that in the laboratory, in the ivory tower of academia and some industrial research labs, we have alternatives,’ continues Halden. ‘But we also have produced a culture of people being used to going through large amounts of material while not asking questions,’
In his view, transforming the plastic production pipeline – making it biodegradable – will be tricky and require great investment. ‘I think we have alternatives, but it is a little bit of a painful process to convert to that. We overuse polymers. We really have become complacent in using so much material. At a small scale, this all works and it’s fine, but given that we have over seven billion people on this planet, we just cannot continue to use these types of plastics,’ Halden says.
Meanwhile, it seems, we are in denial or distracted by familiar foes. Rolsky, whose doctorate focuses on plastic pollution, points out that science has focused obsessively on short-use plastics of little value.
‘We think about styrofoam. We think about straws and silverware and plastic bags which are dangerous threats to the environment, but you don’t really think about plastics that people take so personally,’ Rolsky says.
However, contact lenses perform a critical function, he says. ‘Whether it’s a pilot, whether it’s a doctor – people who really require their eyesight to be clear and precise – it’s something that’s very personal to them,’ adding that he finds it interesting that a very personal, high-value plastic used on a daily basis is taken for granted.
Throughout the ASU research project, people told him they had no idea that casual contact lens disposal was such a bad thing. Only after flushing for x number of years, do they decide to start throwing their lenses in the trash, as Rolsky and his peers encourage. ‘So you see, incrementally, that this starts to change attitudes. And I think this is a really positive message at the end of the day,’ Rolsky says.
The message is so powerful that the study has gone viral, winning coverage from mainstream outlets including USA Today, The Huffington Post and The New York Times. The ASU team hopes that its first-of-a-kind research will drive the industry to take notice and respond accordingly, too.
The idea is that, at least, manufacturers will provide a packaging label that states how to properly dispose of contact lenses, that is, by lumping them with other solid waste. Users need to understand that lenses unthinkingly flushed down the drain may indirectly come back to bite them.