Add millions of used contact lenses to the plastic waste that finds its way into oceans and lakes.
A new study published on Sunday estimates that these smooth transparent discs are often flushed into the sewer instead of being placed in the trash or recycled.
They are only worn for a small day and thus contribute to the danger that they can eventually get caught by polluting a pond, river or road to the sea, says the study presented at a conference by researchers at Arizona State University. .
"I was wondering what happened to these lenses," said Rolf Halden, director of ASU's Biodesign Institute for Environmental Health Engineering. "In the bathroom they can get lost in the sink or go to the toilet, I am an engineer, so let's see how big the problem is."  READ MORE:
* Plastic bag fight won but the war against non-recyclable materials far from over
* The future of recycling lies in the circular economy
* Plastic shopping bags to finally recycle in new project
The answer is, it turns out, that the problem is substantial. Up to 20 percent of American carriers do not throw their old lenses into waste containers, but opt for drainage in sinks and toilets. But because lenses are made of such hard plastics, they do not break completely when they are exposed to microbes. The ASU study showed that after passing a sewage treatment plant they become even smaller pieces that can find their way into fish, birds or other animals.
PUHHHA / 123RF
Of approximately 14 billion contact lenses used every year in the US, the study estimated that a maximum of 50,000 pounds (22,680 kg) would be washed away or would otherwise go to the drain, mostly intended for waste processing plants. How many got into the ocean or the waterways could not be determined.
It is a similar problem to other wreckage in daily life, from straws and forks to plastic bags. Acknowledgment of the number of plastic straws that eventually ends up in the trash, and ultimately the ocean, has made Starbucks say that it will gradually reduce it in 2020. McDonald & # 39; s plans to test alternatives in the US later this year.
Researchers can find only one maker, Bausch + Lomb, who is seriously pursuing a recycling program for contact lenses. Since the program started in November 2016, the company says that the One by One program has collected packaging waste and 2.5 million used lenses for around 7 tonnes of waste.
"We go through it every year and continue to make us aware of it," said Bausch + Lomb, spokeswoman Kristy Marks.
Johnson & Johnson, which makes about 5 billion contact lenses annually through its popular Acuvue brand, tackled the problem by reducing the amount of paper in the packaging and the amount that can be recycled. It has not put the emphasis on the lens itself, which according to him weighs only 30 micrograms.
The ASU study, which was formally presented on Sunday at a meeting of the American Chemical Society in Boston, found that used contact lenses are common in sewage sludge after sewage treatment. A few leftover lenses can usually be found in every 2 pounds of sludge, according to Charles Rolsky, a doctoral student who also worked on the research.
The problem is that because sludge is often deposited on the land, which can eventually wash lenses in lakes or rivers where fish can consume them.
The answer, according to Halden, is not to ban contact lenses. Too many people, including himself, depend on them. And daily disposables, instead of those that carry people for a week or longer, are one of the fastest growing parts of the market for contact lenses and are more convenient and safer.
On the contrary, he said, the better solution is to encourage proper removal. For its program, Bausch + Lomb is working with a company called TerraCycle that specializes in recycling smaller items that would not normally be separated in the standard process.
The problem with lenses is not only the lenses, but also their packaging of foil and plastic, which must be separated to go to recycling plants, said Rick Zultner, director of process and product development for TerraCycle.
"Every waste stream has its unique peculiarities," he said.
– USA Today