The plastic was found in the stomachs of the deepest known marine organisms, according to a scientific study.
The findings in the Royal Society Open Science paper "illustrates that microplastic contaminants occur in the deepest reaches of the oceans."
Researchers at the University of Newcastle have detected the presence of microplastics ingested in the bowels of creatures called amphipods Lysianassoidea.
The organisms were located in six deep ocean trenches around the Pacific Rim, including Japan and Peru-Chile, at depths ranging from 7,000m (22,966ft) to 10,890m (35,728ft).
This is a strong indication that there are probably no areas left in the oceans that are not contaminated by plastic pollution in any way.
More than 72% of the creatures examined contained at least one microparticle, the study found.
Plastic pollution is having a detrimental effect on the world's marine organisms, with an estimated 322 million tonnes of plastic produced annually.
More than five trillion pieces of plastic weighing more than 250,000 tons are currently floating on the surface of the sea.
While most of the plastic present in the oceans is floating on the surface, studies like this show that the degradation and fragmentation of plastics will sink into the underlying habitats of the seabed.
"Microplastics are particularly worrisome in marine environments because they may be similar or smaller in size to prey or particles selected for ingestion by marine organisms," the study wrote.
"The size of microplastics makes them bioavailable, which facilitates entry into the food chain at various trophic levels and bioaccumulation."
The study found that the extent of adverse effects of plastic pollution on marine life is not fully understood, although it is known to negatively affect about 700 marine species, mainly by ingestion.
Despite living in remote habitats, the research team discovered synthetic and plastic fibers, including nylon, polyethylene, and polyvinyl alcohol, within most of the amphipods examined.
As many deep-sea organisms, including amphipods, have evolved to ensure feeding success on rare occasions, the likelihood of ingesting new foreign bodies is high.
Microplastics consumed by small prey species may have implications for the entire food chain, since amphipods are fish food and crustaceans that are consumed by predators, including birds and humans.
"This study reports the deepest record of microplastic ingestion, indicating that anthropogenic debris is bioavailable to organisms in some of the deepest places in the Earth's oceans," the researchers wrote.