Face coverings such as surgical masks are a crucial component in the fight against the spread of SARS-CoV-2, but one unintended consequence of their widespread use is the littering of masks in parking lots, streets, parks and beaches. Improperly discarded surgical masks are not only unsightly but can also be a source of environmental pollution, and can even make their way into the oceans and impact marine ecosystems. Researchers at the City University of Hong Kong sought to further investigate how this type of pollution may affect sea life, discovering that a single mask can release thousands of microplastics with adverse effects for organisms that may consume them.
For their study, the researchers tested both new polypropylene surgical masks as well as discarded masks collected from a beach in Hong Kong. The masks were soaked in a bottle of artificial seawater and shaken in a mechanical shaker for a 9-day period. Microplastic samples from each mask were collected every two days during the shaking process and examined under a stereomicroscope as well as analyzed through Fourier transform infrared (FTIR) spectroscopy. The researchers observed significant damage to the mask fibers under the microscope and ultimately determined that a mask weighing about 3 grams could release approximately 3,000 microplastics over 9 days in seawater. Team further estimated that a single mask could release a total of 0.88 million to 1.17 million microplastics during its complete decomposition.
The team also examined the effects that microplastics from polypropylene surgical masks could have on marine life. The researchers exposed copepods (Tigriopus japonicus) to artificial seawater containing up to 100 microplastics per milliliter and found that the small crustaceans ingested the microplastics, which accumulated inside their intestines. Compared to copepods that were not exposed to microplastics, the exposed copepods had their reproduction fecundity reduced by up to 22%, and the maturation development time of the exposed copepods was also about 5.6% longer than that of their non-exposed counterparts. Copepods play a critical role in the marine food chain as prey for many shrimps and fish, meaning both microplastic accumulation and reduced fecundity could ultimately have an impact on many higher-level marine organisms. This study was published in Environmental Science and Technology Letters.
Henry Yuhe He, who led the research, explained he felt driven to conduct this study after spotting improperly discarded masks on a beach while walking his dog.
“I saw one mask wedged between rocks on the shore and another floating on the water surface. Since all the masks are made of plastics and may be releasing microplastics, improperly discarded masks will affect the marine environment. I believe this problem will continue for many years in the post-pandemic era,” He said.
Previous research has estimated that as many as 1.56 billion masks were released into oceans in 2020. The research team urged members of the public to dispose of their face masks properly and also called for more effective waste management strategies to ensure these masks don’t end up in ocean waters.
Photo: An improperly discarded surgical mask on the Hong Kong shore. Credit: City University of Hong Kong