Bottled water sampled from manufacturers around the world is teeming with microplastics — tiny plastic particles that are often too small to see — according to a new report.
Tests of 250 bottles from 11 bottled water brands revealed microplastics in 93 percent of the samples, with an average of 325 particles per 34 fluid ounces (1 liter) of water.
These findings, discovered by scientists at the State University of New York in Fredonia, sound alarming. However, the report was not submitted for publication in a scientific journal, a process that involves extensive review of a study's methods and findings by scientists who were not involved in the research. Rather, the investigation was launched and then released by Orb Media (OM), a nonprofit that uses journalism and data science to investigate global environmental issues, according to the company's website.
The consequences of these findings for human health are "unknown," OM representatives said in a statement.
Microplastics measure under 0.2 inches (5 millimeters) in length — about the size of a sesame seed or smaller — and they originate from many sources, such as microbeads that are commonly found in health and beauty products, according to the National Oceanic and Atmospheric Administration (NOAA).
Humans have produced an estimated 9 billion tons of plastic, Live Science previously reported. Plastic is the most common form of rubbish found in the world's oceans, and microplastics are so small that they can evade methods for collecting or filtering plastic trash; studies have shown that microplastics are present in nearly every environment on Earth and can be found in the guts of many types of sea birds and marine life, according to NOAA.
And according to the new report, microplastics are also widely distributed in bottled drinking water. Regardless of whether the findings are verified by scientists unaffiliated with the study, the health risks of microplastics are far from known and depend on the quantities that are ingested and how long the minuscule particles linger in a person's gut, experts say.
For the study, reporters with Orb Media bought prepackaged cases of water from locations in nine countries and across five continents, examining internationally distributed brands that included Dasani, Evian, San Pellegrino, Nestlé Pure Life and Aquafina.
A dye called Nile red helped researchers to find the microplastics. First used in 1985, Nile red adheres to plastic and fluoresces through an orange filter when viewed under a blue-green wavelength, which enables scientists to distinguish plastic particles from sediment, according to a study published in October 2016 in the journal Scientific Reports.
The study authors then filtered the water to 1.5 microns (0.0015 millimeters) — an area "smaller than a human red blood cell" — and counted the trapped fluorescing particles using an application called Galaxy Count. Molecular analysis identified particles such as polyethylene terephthalate (PET), nylon and polypropylene in quantities of up to 10,000 particles per 34 fluid ounces (1 liter) in the water tested, according to the report.
However, bottled water manufacturers contacted by OM regarding the study claimed that the findings greatly overstated the amount of microplastics in their water, and Nestlé handed over their own test results from six bottles that contained "between zero and five plastic particles per liter," according to the report.
Concerns about ingesting microplastics stem from their ability to accumulate high concentrations of pollutants such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), which can then be absorbed into gut tissue, scientists reported in a study published in June 2016 in the European Food Safety Authority Journal.
OM partnered with media organizations in 10 countries — the U.K., Canada, Spain, Finland, Bangladesh, Brazil, Sweden, Germany, Indonesia and India — to distribute the study's results, representatives said in the statement.
Coverage of the study by the BBC — one of OM's media partners — announced that the World Health Organization (WHO) is gearing up to "launch a review" into microplastics and their impact on public health, following the study's findings.
However, though WHO is aware of the study and its findings, much more data would be required on microplastics' impact on human health for the health organization to take action, WHO representative Fadéla Chaib told Live Science in an email.
"For WHO to make an informed risk assessment, we would need to establish that microplastics occur in water at concentrations that would be harmful to human health," Chaib said. But for now, information on microplastics in drinking water is "very limited," and there is no information to suggest that its presence is dangerous to people, Chaib said.
As part of the organization's ongoing analysis of emerging evidence about microplastics, WHO will monitor and review evidence gaps to determine where more research is required, according to Chaib.
"WHO's priority remains promoting access to safe water for 2 billion people who currently use and drink contaminated water," she told Live Science.
The report has been submitted for peer review; the methods that the group used to test for plastic particles "are readily available," according to an OM FAQs document about the project.
"We encourage additional testing by others following the same rigorous standards," OM representatives said in a statement.