TY - JOUR
T1 - Nationwide Mass Inventory and Degradation Assessment of Plastic Contact Lenses in US Wastewater
AU - Rolsky, Charles
AU - Kelkar, Varun P.
AU - Halden, Rolf U.
N1 - Funding Information:
All data required to supplement the conclusions of the paper are listed in the main text or Supporting Information . The online study was supported through Arizona State University Institutional Review Board (IRB), STUDY00008394. Acknowledgments
Funding Information:
This work was supported in part by the National Institute of Environmental Health Sciences (NIEHS) Grant Number R01ES020889 and its supplements and by the Virginia G. Piper Charitable Trust [Award LTR 05/01/12].
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/10/6
Y1 - 2020/10/6
N2 - Plastics pose ecological and human health risks, with disposable contact lenses constituting a potential high-volume pollution source. Using sales data and an online survey of lens users (n = 416) alongside laboratory and field experiments at a conventional sewage treatment plant, we determined the environmental fate and mass inventories of contact lenses in the United States. The survey results revealed that 21 ± 0.8% of lens users flush their used lenses down the drain, a loading equivalent to 44 »000 ± 1700 kg y-1 of lens dry mass discharged into US wastewater. Biological treatment of wastewater did not result in a measurable loss of plastic mass (p = 0.001) and caused only very limited changes in the polymer structure, as determined by μ-Raman spectroscopy. During sewage treatment, the lenses were found to accumulate as fragments in sewage sludge, resulting in an estimated accumulation of 24 »000 ± 940 kg y-1 of microplastics destined for application on US agricultural soils contained in sewage sludge. Recycling of the contact lenses and their packaging amounted to only 0.04% of the total waste volume associated with contact lens use. This is the first study to identify contact lenses and more specifically silicone hydrogels, as a previously overlooked source of plastic and microplastic pollution.
AB - Plastics pose ecological and human health risks, with disposable contact lenses constituting a potential high-volume pollution source. Using sales data and an online survey of lens users (n = 416) alongside laboratory and field experiments at a conventional sewage treatment plant, we determined the environmental fate and mass inventories of contact lenses in the United States. The survey results revealed that 21 ± 0.8% of lens users flush their used lenses down the drain, a loading equivalent to 44 »000 ± 1700 kg y-1 of lens dry mass discharged into US wastewater. Biological treatment of wastewater did not result in a measurable loss of plastic mass (p = 0.001) and caused only very limited changes in the polymer structure, as determined by μ-Raman spectroscopy. During sewage treatment, the lenses were found to accumulate as fragments in sewage sludge, resulting in an estimated accumulation of 24 »000 ± 940 kg y-1 of microplastics destined for application on US agricultural soils contained in sewage sludge. Recycling of the contact lenses and their packaging amounted to only 0.04% of the total waste volume associated with contact lens use. This is the first study to identify contact lenses and more specifically silicone hydrogels, as a previously overlooked source of plastic and microplastic pollution.
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U2 - 10.1021/acs.est.0c03121
DO - 10.1021/acs.est.0c03121
M3 - Article
C2 - 32869978
AN - SCOPUS:85092681217
SN - 0013-936X
VL - 54
SP - 12102
EP - 12108
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 19
ER -