Contact lenses are so small that it’s easy to think you can flush them down the toilet and they’ll simply dissolve, but that’s far from the truth. The scientists behind a study presented at the American Chemical Society’s national meeting and exposition warn that flushing contact lenses add to the problem of microplastics littering both land and sea.
An enormous number of contact lenses wind up contaminating the environment, the study shows, as 21% of wearers flush them down the toilet or the sink. In the United States, 14 billion contact lenses get trashed each year, including 3 million that get flushed down the toilets or washed down sink drains, says Rolf Halden, the director of the Biodesign Center for Environmental Health Engineering at Arizona State University and one of the authors of the study.
As much as 50 tons of contact lenses could end up in American water supplies every year because, like all plastics, they don’t disintegrate.
Halden and his colleagues surveyed 409 contact wearers about their method of disposal and found that approximately 28,000 pounds of lenses are turned into treated sewage sludge each year. That sludge gets used as crop fertilizer. That means the lenses sink into the soil, where they can affect small animals and insects and may eventually end up in groundwater sources that flow into the ocean.
The findings are concerning. While there has been a great deal of research done on the effects of microplastics in the ocean, few studies have looked at their impact on land.
Lisa Watkins, a graduate student and the lead of Cornell University’s Soil and Water Lab microplastics-research team, said:
“We find that earthworms carry that plastic [from the sewage sludge] into their burrows. But there haven’t been that many studies on what happens to plastics on land.”
“If [microplastics] get out in sewage sludge and end up in the environment, they might pose a risk to aquatic organisms – think mussels and fish. We don’t know if these plastics go up the food chain. Earthworms take them up, birds could eat them, and what happens when a bird ingests the contact lens? Does it disrupt the G.I. tract? These are all unanswered questions.”
The team tested what happened to contacts when they were placed in liquids of varying densities and found that they always sink to the bottom – a potentially dangerous situation for bottom-feeding fish, who mistake the lenses for food. It will turn your stomach to learn that some of the contact particles “find their way to the human food supply.” 
The problem could be reduced – though not eliminated – if contact lens manufacturers simply added disposal instructions to labels, according to Halden. He said he didn’t find any directions for disposal on the 11 brands of contact lenses he looked at. Most of them didn’t even include recycling labels. 
“We hope that manufacturers in the future will take a more proactive approach.”
Ideally, contact wearers should recycle their lenses if they live in an area that allows it, according to the American Optometric Association. 
In a statement, the organization said:
“The regular garbage is the second option. Down the sink drain or toilet is never recommended and is discouraged due to the impact on our environment.”
Bausch & Lomb has a recycling program for its Biotrue Line and took in 1.9 million contacts in 2017.
There is always the option of wearing glasses, which last longer than contacts, generally cost less over time, and come without the risk of an eye infection.
 The Atlantic
 CBS News