TOOTHBRUSH bristles, bottle fragments and clothing fibres – microplastics – were found in the guts of every marine mammal examined in a new UK-wide study.

Dolphins, whales and seals had all ingested the material.

Each of the 50 animals had been washed up on the shoreline, with some discovered in Scotland.

Though the specimens died of a variety of causes, those that died due to infectious diseases had taken in a slightly higher number of particles than those killed by other factors.

READ MORE: Animals dealing with our microplastics, says Scottish Marine Science Association

Lead author Sarah Nelms, of Exeter University and Plymouth Marine Laboratory, called the results "shocking, but not surprising".

And Professor Brendan Godley, of the Centre for Ecology and Conservation at Exeter University said: “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. Our findings are not good news.”

Godley added: “We can’t draw any firm conclusions on the potential biological significance of this observation. We are at the very early stages of understanding this ubiquitous pollutant. We now have a benchmark that future studies can be compared with."

Published in the journal Scientific Reports, the Greenpeace-supported study used samples provided by the Scottish Marine Animal Stranding Scheme (SMASS), Cornwall Wildlife Trust’s Marine Stranding’s Network and the Cetacean Strandings Investigation Programme run by the Zoological Society of London.

Animals examined included bottlenose dolphins, grey seals, harbour porpoise and pygmy sperm whales.

More than 80% of microplastic fragments were synthetic fibres, which can come from clothes, fishing nets and toothbrushes.

Co-author Dr Andrew Brownlow of SMASS, part of Scotland’s Rural College, said: “This is a concerning indication of the state of our oceans.

"While the burden of microplastics was small, in both size and number, and there was no indication that they were causing any direct harm to the animal, we still don't know enough about the effects of ingested microplastics to be confident they are totally benign.

“Given the apparently almost ubiquitous nature of microplastics in our ocean life, this is an area we really need to understand in more detail.”

Dr Penelope Lindeque, head of the marine plastics research group at Plymouth Marine Laboratory, said: “It is disconcerting that we have found microplastic in the gut of every single animal we have investigated in this study.

“Over the years we have found microplastic in nearly all the species of marine animals we have looked at, from tiny zooplankton at the base of the marine food web to fish larvae, turtles and now dolphins, seals and whales.

“We don’t yet know the effects of these particles on marine mammals. Their small size means they may easily be expelled, but while microplastics are unlikely to be the main threat to these species, we are still concerned by the impact of the bacteria, viruses and contaminants carried on the plastic.

“This study provides more evidence that we all need to help reduce the amount of plastic waste released to our seas and maintain clean, healthy and productive oceans.”