WASHINGTON (Reuters) - A team of scientists, led by the United States, has found tiny pieces of plastic in Arctic ice core samples, highlighting the threat this type of pollution poses to marine life, even in the deepest waters on the planet.

The researchers used a helicopter to land on ice and collect samples during an 18-day mission across the Northwest Passage, a perilous road linking the Pacific and Atlantic oceans.

"We spent weeks looking at what looked a lot like pristine white snow from seawater floating on the ocean," said Jacob Struck, a graduate researcher at the University of Rhode Island who conducted an initial analysis of the ice corp.

"When we looked at it very closely and found it very clear that it was contaminated when viewed using the right means, we had a little bit like a stomach punch," he told Reuters by telephone on Wednesday.

Strock and colleagues found plastic particles stuck in ice from Lancaster Sound, an isolated Arctic water in Canada that they assumed was relatively protected from drifting plastic contamination.

The team pulled 18 pieces of ice pulp up to two meters in length from four places and found grains and thin pieces of plastic visible in different shapes and sizes.

The panic is reminiscent of the fear that explorers found when they found plastic residues in the Pacific Ocean's Mariana Trench, the deepest point on Earth, during submarine dives this year.

But plastic particles, known as microplastics, have been found by scientists to help shed light on the extent to which the waste problem has reached epidemic levels. The United Nations estimates that 100 million tons of plastic have been dumped into the oceans to this day.

The researchers said the ice samples appeared to be at least one year old and were probably swept away to Lancaster Sound from further north central Arctic.