Researchers have found an alarming total of 492 pieces of plastic inside the intestines of deceased sea turtles in the Mediterranean, according to a recent study published in the journal Marine Pollution Bulletin.

Research led by the University of Exeter and the North Cyprus Society for the Protection of Turtles showed that more than 40 percent of 135 loggerhead turtles they found washed ashore or accidentally entangled in fishing nets off the coast of northern Cyprus contained plastic larger than 5 millimeters.

According to the study, the plastics were largely sheetlike (62 percent), either clear (41 percent) or white (25 percent), and the most common polymers identified were polypropylene (37 percent) and polyethylene (35 percent).

"It's likely that turtles ingest the plastics that mostly closely resemble their foods," said Dr Emily Duncan, the author of the paper, according to the University of Exeter.

"We still don't know the full impacts of macroplastic on turtles' health, but negative effects could include causing blockages and limiting nutrition," Duncan added.