A disposable mask has been found in the feces of a juvenile green sea turtle caught off Japan's northeastern coast, a study by a team of Japanese researchers recently showed, raising concerns that plastic debris related to COVID-19 is contaminating the marine ecosystem.

While sea turtles have been known to accidentally ingest plastics for some time, no face mask had been found during the 15-year survey of the region prior to the pandemic, according to the team from the Tokyo University of Agriculture and Technology and the University of Tokyo.

Reports of disposable masks entering the ocean have increased in coastal areas around the world since the outbreak of the coronavirus.

In the paper published in the Marine Pollution Bulletin earlier this month, the team also confirmed that commercially available masks contain stabilizers to prevent plastic from deteriorating due to ultraviolet rays. The additives are considered to be endocrine disruptors, meaning they can interfere with hormonal systems of organisms.

The juvenile green turtle was caught alive in a set net off Iwate Prefecture in August 2021, and is currently being kept in captivity.

The item later confirmed to be a nonwoven polypropylene mask was found in its feces by Takuya Fukuoka, a researcher at the Tokyo University of Agriculture and Technology.

Hideshige Takada, a professor at the same university who was also involved in the study, said the findings suggest that marine life is being exposed to chemical substances through the accidental ingestion of plastic debris.

With the use of masks and other personal protective equipment likely to continue for some time, "We need to take measures such as ensuring appropriate waste management and changing additives," he said.