It might be time to update your contact lens care education to include proper disposal, according to a new study. Researchers at Arizona State University recently calculated that American contact lens patients are incorrectly disposing of anywhere from six to 10 metric tons of plastic lenses each year, which end up in our waterways.1

The researchers first used patient surveys to discover 15% to 20% of daily disposable contact wearers flush their used lenses down the sink or toilet. With 45 million disposable contact lens patients in the United States, that plastic can add up to a significant environmental impact, the researchers said while presenting the data on August 20 at the 256th National Meeting & Exposition of the American Chemical Society.1

Compounding the issue is the fact that wastewater treatment facilities aren’t designed to fully break down the type of plastics used for contact lenses. The researchers exposed various contact lenses polymers to microorganisms present at wastewater treatment plants and found the combinations of polymethylmethacrylate, silicones and fluoropolymers degrade only somewhat, creating what they call microplastics—materials marine life can easily mistake for food.1 This could even lead to unwanted human exposures to contaminants and that stick to the surfaces of the plastics, the researchers speculate.

While the environmental impact may pale in comparison to other, larger pollutants, it’s worth our attention and further study, the researchers emphasize. “Disposable contact lenses are emerging contaminants of concern that cause environmental pollution, present a potential physical threat to susceptible aquatic biota, may contribute to microplastic pollution, and have the potential to adsorb, accumulate, and transport harmful persistent organic pollutants into aquatic and terrestrial environments,” the study abstract concludes.2

1. The environmental cost of contact lenses. American Chemical Society. August 19, 2018.

2. Rolsky C, Kelkar V, Halden RU. Chemical and physical changes in a variety of contact lenses during the wastewater treatment processes. Abstract presented at the 256th National Meeting & Exposition of the American Chemical Society, August 20, 2018; Boston.