Researchers found evidence of microplastics in 93 percent of tested bottles of water.

The startling new report shows that bottled water may have more plastic pieces than tap water, prompting a review from the United Nations’ World Health Organization.

The new study — which was conducted by scientists based at State University of New York at Fredonia — tested 259 bottles of water from 19 locations in nine different countries. The result: an average of 325 microplastic particles for every liter of water.

Plastic particles in the 0.10 millimeter size range are considered micro plastics.

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The bottles used for the test were purchased in Brazil, China, Kenya, Lebanon, Mexico, India, Indonesia, Thailand and the United States. They included the following brands: Aqua (Danone), Aquafina (Pepsi Co.), Bisleri (Bisleri International), Dasani (Coca-Cola), Epura (Pepsi Co.), Evian (Danone), Gerolsteiner (Gerolsteiner Brunnen), Minalba (Grupo Edson Queiroz), Nestle Pure Life (Nestle), San Pellegrino (Nestle) and Wahaha (Hangzhou Wahaha Group).

Scientists used nile red dye — which typically sticks to plastics rather than natural materials — to identify plastic particles in the samples. Nestle claims that this methodology can generate false-positive results.

WHO says that there is no evidence of microplastics having a negative effect on human health, but the organization is launching a review of this emerging area of concern, according to The Guardian.