Plastics have been found in minute traces throughout the Great Lakes, washed ashore on the most desolate location of the Pacific Ocean, and in the wastewater from washing machines in the developed world.

But tiny pieces of plastic are also found in the tap water of billions of people across the world, according to a new study released today.

“Invisibles: The plastic inside us” is a survey of tap water samples form the developed and developing world, undertaken by scientists at the University of Minnesota and the State University of New York, who worked with a non-profit media company called Orb Media on the findings.

The 159 samples came from around the world – and a total of 83 percent of them tested positive for plastic fiber traces.

Thirty-three samples came from the United States, including locations like the U.S. Capitol complex and the headquarters of the Environmental Protection Agency in Washington, D.C., and the Trump Grill in New York City.

A total of 94 percent of these U.S. samples showed the presence of plastic.

Plastics were also found in a majority of the samples from across the world: Beirut (94 percent of samples), New Delhi (82 percent), Kampala, Uganda (81 percent), Quito, Ecuador (75 percent), Jakarta, Indonesia (76 percent), and a selection of European sources (72 percent).

The samplings were collected in bottles made of high-density polyethylene (HDPE), since it would be easily discernible from the trace plastic fibers subject to testing.

They were shipped to the University of Minnesota for tests, assessing the fibers greater than 100 microns in size using a filtration system and a “fastidious” laboratory process involving recurrent cleaning of the equipment.

The likely source for the plastic source is clothing made of synthetic materials, which emits fibers when washed, the authors conclude. Although the water treatment process in most areas removes the bulk of the particles, many persist through the cycle of use and re-use, they conclude.

The health effects of drinking trace plastic in water – or eating food prepared with that water – remains unclear, the researchers added.