Microplastics are one of the planet’s most widespread and complex contaminants, having been found at the bottom of the ocean and in the bodies of wild animals. Now, new research published in Scientific Reports has found that microplastics as well as synthetic fibers commonly found in clothing have taken up residence in the stomachs of seabed-dwelling sharks found off the coast of the United Kingdom. The exact impact of plastic on the health of the sharks isn’t yet known, but researchers fear their floor-dwelling lifestyle is putting them more at risk of ingesting the synthetic materials. 

The researchers, from the University of Exeter, UK, looked at four species of demersal (seabed-dwelling) sharks to see if they had been contaminated by synthetic materials leaked into the ocean. They found that 67 percent of the animals contained microplastics and other manmade fibers such as synthetic cellulose, which is a common constituent of clothing.

The researchers say the findings highlight the “pervasive nature of plastic pollution” as they were surprised by not only how common the incidence of microplastics was but also that synthetic fibers from clothing were starting to accumulate in the wild animals.

“When clothes are washed, or items are discarded as litter, tiny fibers are released and these often flow into water sources and out to sea,” the World Health Organization (WHO) said in the video about findings.

“Once in the sea, microfibers can either float or sink to the bottom, which is where these sharks live. The fibers could then be ingested via the sharks’ food, which is mostly crustaceans, or directly through the sediment on the seabed. In terms of the other types of microplastics we found, many of these may have come from fishing lines or nets.”

The species studied were the small-spotted catshark, starry smooth-hound, spiny dogfish, and bull huss, which live at depths varying from 5 to 900 meters (16 to 2,952 feet) beneath the ocean surface and usually feed on the seafloor. All of the specimens examined were accidental bycatch from a demersal hake fishery that operated around the North-East Atlantic and Celtic Sea. The researchers know their sample size is small but state that they believe this preliminary finding is indicative that microplastics and synthetic fibers have likely made it into the bodies of larger sharks.

“We were not expecting to find microfibers from textiles in so many of our native shark species,” said study co-author Professor Tamara Galloway in a statement.  “Our study highlights how important it is to think before we throw things away.”