There remains a lot we don't know about the whereabouts of the all the plastic waste that washes into the ocean each year, but scientists are continuing to discover bits and pieces in increasingly concerning places. The latest study in this area has uncovered evidence of plastic waste in the stomachs of sea turtles hailing from all corners of the globe, shedding new light on the far-reaching implications of our plastic pollution problem.

The trouble with the millions of metric tons of plastic waste that make their way into the sea each year (aside from the obvious) is the fact that much of it is broken down by ocean forces into tiny fragments called microplastics. Though there are advanced distribution maps and other tracking tools in development, we currently have no way of knowing where most of it ends up.

But there are some undesirable places we know microplastics do exist, and the list keeps on growing. This year alone scientists have found various microplastics in human stools all over the world and packed into Arctic sea ice in huge abundance. They also discovered them in 93 percent of bottled water.

The concern is that we don't really know what effect the ingestion of plastics can have on living creatures, because our understanding of the reactions between its chemicals and those organisms is very limited. To that end, the World Health Organization launched a health review earlier this year to try and fill the gaps.

Which brings us to the turtles. Researchers from the University of Exeter and Plymouth Marine Laboratory carried out autopsies on 102 turtles from the Pacific, Mediterranean and the Atlantic oceans, covering all seven species. They found microplastics in every single one, with the most common type being the fibers uses in clothes, cigarette filters and fishing nets.

"Their small size means they can pass through the gut without causing a blockage, as is frequently reported with larger plastic fragments," said lead author Dr Emily Duncan from the University of Exeter. "However, future work should focus on whether microplastics may be affecting aquatic organisms more subtly. For example, they may possibly carry contaminants, bacteria or viruses, or they may affect the turtle at a cellular or subcellular level. This requires further investigation."

The research was published in the journal Global Change Biology.