Jan. 31 (UPI) -- Researchers at the University of Exeter found microplastics in all 50 animals they studied in a recent survey of beached marine mammals, including 10 species of dolphins, seals and whales.
Synthetic fibers constituted the majority of plastic debris recovered from the animals, strands from clothes, fishing nets and toothbrushes. One quarter of the animals contained plastic fragments, likely from food packaging and plastic bottles.
"It's shocking -- but not surprising -- that every animal had ingested microplastics," lead author Sarah Nelms, researcher at Exeter and the Plymouth Marine Laboratory, said in a news release.
Because scientists found relatively low concentrations of microplastics in the marine mammals, scientists think most of the debris would have eventually passed through their intestines or been regurgitated. But that doesn't mean the pollution can't harm large animals.
"We don't yet know what effects the microplastics, or the chemicals on and in them, might have on marine mammals," Nelms said. "More research is needed to better understand the potential impacts on animal health."
Autopsies showed the beached animals died for a variety of reasons. Those that died from infectious disease hosted slightly higher concentrations microplastics, suggesting the debris could hamper the mammals' immune systems. But scientists say more research is needed to confirm such a link.
"We are at the very early stages of understanding this ubiquitous pollutant," said Brendan Godley, researcher at Exeter's Center for Ecology and Conservation. "We now have a benchmark that future studies can be compared with."
The new study -- published this week in the journal Scientific Reports -- isn't the first to reveal the ubiquity of microplastics in the guts of marine species, but it's worrisome news, nonetheless.
"Marine mammals are ideal sentinels of our impacts on the marine environment, as they are generally long lived and many feed high up in the food chain," Godley said.