This article is more than 5 years old. Information may no longer be current.
Study finds contact lenses disposed down the drain do not degrade
Click Here to Manage Email Alerts
A research team from Arizona State University garnered national media attention as a result of their study at a wastewater treatment plant showing that contact lens polymers do not degrade when disposed of via shower or sink drain or the toilet.
Specifically, they investigated contact lens resistance to microbial attack and mass flows of contact lenses to terrestrial environments from wastewater treatment plants.
“We did not observe any significant biodegradation of contact lenses in a full-scale wastewater treatment plant when lenses of different brands were exposed to treatment conditions for hours to several days,” Rolf U. Halden, PhD, from the Center for Environmental Health Engineering at the Biodesign Institute at Arizona State University, told Primary Care Optometry News in an interview.
Of the 11 lens polymer types tested, all polymers persisted during the biological treatment with limited structural changes.
The lenses are heavier than wastewater and sink to the bottom and are recoverable from the sludge – the biproduct of wastewater treatment, Halden said.
Contact lenses were found to transfer into digested sludge at an estimated national mass flow of at least 44,000 pounds per year in the U.S. National mass flow is the flow volume of the lenses and of the packaging material. The volume was divided post-use based on the disposal route, Halden explained.
They also estimate that the mass of contact lens polymers deposited on U.S. land annually exceeds 24,250 pounds of plastic mass.
“Mass flows were calculated for the lenses themselves as well as for the packaging material (polypropylene blister packs with aluminum lids) destined for disposal into solid waste, as information on recycling options typically are not provided by the manufacturer,” Halden added.
“We are confident about the order of magnitude; the problem is real as confirmed by the detection of lenses in sewage sludge,” he said.
The risks posed by this pollution are currently unknown but could include ecological and secondary risks from concentration and accumulation of persistent toxic environmental pollutants, according to an extended abstract of the study.
Improper disposal habits may be due to consumers misunderstanding the materials, Halden said.
“From the appearance of the lenses, it’s hard for consumers to deduce that they will behave like plastic and not degrade. The lenses are so moist and flexible, and they disappear when submerged in water,” he said.
Halden said he was disappointed to learn that most contact lens packaging does not disclose proper disposal information for consumers to follow.
The researchers also received 410 responses to an online survey highlighting disposal practices. Responses indicated that about 20% of U.S. contact lens wearers dispose of contact lenses down the drain.
“One out of five of these products are starting a journey into the wastewater treatment plant,” Halden said.
Based on the sample size, he is confident that this represents the average behavior among consumers.
PCON Editorial Board member Kerry Giedd, OD, MS, FAAO, believes that this is a rather shocking statistic and a wake-up call to eye care providers.
“While I occasionally observed patients removing their lenses and washing them down the drain, I never suspected the prevalence of this behavior was so high,” Giedd told PCON. “I’ll admit I never actually asked patients how or where they discarded their lenses and, historically, we never proactively educated our patients on ‘proper’ disposal as a part of our contact lens training — we just assumed they would place them in the trash or, now, recycle them.”
Regarding this study, Halden said, “We gained a lot of interest from the media, and I hope it also raises the interest of the manufacturers, because I think there’s great opportunity to improve the value and lifecycle of these materials.”
He said the industry should start by providing the consumer with a better understanding of the potential risks of improper disposable practices.
Halden also recommends reminding wearers that contact lenses are a plastic medical device and should be disposed of properly. It would also be more desirable to develop materials that more easily degrade.
“If there were opportunities to work with industry to design better polymers that are designed for better attenuation over time, that would be good,” Halden added. “There is a desire to design materials inert for biological attack, but not for an eternity. After the wear is complete, there should be a plan for attenuation and disappearance of the material if it gets into the environment.”
While this would certainly be ideal, Giedd noted that combining the quest for more environmentally friendly polymers with the need for optical integrity, optimal comfort and patient safety creates a tall order.
Halden and Giedd agree that if manufacturers do a better job on package labeling, fewer lenses will end up in wastewater.
“Now that researchers have discovered the scale of this problem, eye care providers and contact lens manufacturers are both charged with the responsibility to respond and educate consumers,” Giedd said.
“We don’t want to discourage contact lens wear but encourage better usage and proper disposal so everyone feels better about the daily use of these products,” Halden said.
“We should reduce our amount of plastic we use in daily life,” he added, “but one of the last items to compromise on are those for medical purposes. We certainly want to advocate good hygiene, and good eye sight is important. We are not discouraging contact lens wear. It’s easy to understand, due to the large volume of lenses being worn, that there is a need to look at the material lifecycle and close it as soon as possible.”
Giedd added that even those consumers who believe they are helping the environment by placing lenses and/or lens packaging in their residential recycling bins are not achieving their goal. Contact lenses are sorted out as waste due to their small size and ultimately end up in landfills across the U.S., she said.
Giedd strongly encourages eye care providers to participate in the free One by One contact lens recycling program sponsored by Bausch + Lomb, which makes it possible for practices and patients to properly recycle any brand of contact lenses and keep the lens waste out of the ecosystem, she said.
This program was launched in 2016 and, to date, more than 4 million lenses, blister packs, and foil tops have been recycled, equating to nearly 30,000 pounds of contact lens materials diverted from landfills and oceans, according to Giedd.
To participate and sign up as an official contact lens recycling center, ECPs should visit www.bauschrecycles.com.
“Our practice has participated in the One by One program since its launch and it has gained increasing momentum with ECPs nationally in recent months,” Giedd said.
“In addition to helping us become better stewards of our planet, this program has been a practice builder, as our patients are more likely to choose daily disposable contact lenses when recycling is an option and they appreciate and value our concern for the environmental impact of our clinical recommendations,” she concluded.
Halden said the study results are pending publication in a peer-reviewed journal, and PCON will continue reporting on the research at that time. – by Abigail Sutton
Disclosures: Giedd is a consultant to Bausch + Lomb. Halden reported no relevant financial disclosures.