A single bottle of water can contain dozens — or even thousands — of tiny plastic particles, according to a news story that's prompted the World Health Organization to launch its own review.

Tests on more than 250 bottles showed  almost all had contamination from microplastic particles that included polypropylene, nylon, and polyethylene terephthalate (PET), according to a story in Orb, a nonprofit journalism organization.  However, a few bottles showed no presence of plastics at all.  In all, scientists working with the publication found plastic in 93 percent of the samples.

A microplastic is generally defined as particles less than the size of a sesame seed, according to the National Oceanic and Atmospheric Administration.

Orb tested 11 popular name brands, including Nestle Pure Life, Aquafina, Evian and Dasani. Company representatives from two of the brands confirmed their water contained microplastics, but said that the Washington, D.C.-based organization was significantly overstating the amount.

The testing comes on the heels of a growing global sentiment against plastic, single-use bottles and microplastics.  Last month, scores of British politicians recently announced they were giving up bottled water for Lent after growing reports of single use plastic containers accumulating in oceans.  Plastics — which can come from a range of items — are the most prevalent type of debris found in the oceans and Great Lakes in the U.S., NOAA said.

Orb conducted the tests with the State University of New York for plastic particles in the .10 millimeter size range or particles about the size of a hair.  The tests, using an infrared microscope, showed a global average of 10.4 plastic particles per liter.

Nestle Pure Life had the highest maximum number of particles per liter at more than 10,000.  In response, however, Nestle tested six of its own bottles from three locations. The company said its tests showed between zero and five plastic particles per liter.

The story prompted the WHO to say it would launch its own review, according to an article Thursday by the BBC.  Bruce Gordon, coordinator of WHO's water and sanitation program, said the organization did not want to be alarmist, but nonetheless noted that a lot of people drink bottled water so a review was warranted.  The question, he said, is whether eating or drinking particles of plastic over long periods of time could have a cumulative effect on the human body.

"When we think about the composition of the plastic — whether there might be toxins in it, to what extent they might carry harmful constituents, what actually the particles might do in the body – there's just not the research there to tell us," Gordon told the BBC. "We normally have a 'safe' limit but … to define that, we need to understand if these things are dangerous, and if they occur in water at concentrations that are dangerous."

The Orb article said reporters' findings "suggest that a person who drinks a liter of bottled water a day might be consuming tens of thousands of microplastic particles each year."  However, it also said it remains a mystery whether that could impact a person's health.