Invisibles
The Plastic Inside Us
An Investigative Report By: Chris Tyree, Journalist, Email and Dan Morrison, Journalist, Email
We began our research into microplastic pollution with a simple question: If microscopic plastic particles and fibers are in the world’s oceans and freshwater locations, could they be in drinking water as well? We scraped the internet for scientific studies on this subject and could not find a drop of public research addressing the topic.
So we conducted an observational experiment of our own, collecting more than 150 tap water samples from cities and towns on five continents.
The samples were tested by researcher Mary Kosuth at the University of Minnesota School of Public Health in a study supervised by Sherri Ann Mason, a pioneer in the study of microplastic pollution. Professor Mason’s research documenting the broad extent of microplastic pollution in North America’s Great Lakes was used to support a partial legislative ban on products using microbeads in the United States and Canada.
Our half-liter samples were collected by a combination of scientific professionals, informed volunteers, and members of the Orb team using protocols to limit contamination by airborne fibers. (The protocols were developed by Professor Mason, who is chair of the department of geology and environmental sciences at the State University of New York at Fredonia.) The samples came from mega-cities like New Delhi and Jakarta, and from towns as small as Pinebluff, North Carolina, population 1,439.
Each sample was collected in a bottle made of high-density polyethylene, or HDPE. Why plastic? For one, it’s lightweight, and our samples were shipped by air from locations around the world. If fragments of HDPE occurred in our water samples, Professor Mason assured us, they would be easy to differentiate from plastic fibers. Study participants were asked to leave the water running for one minute; rinse the interior of their bottles three times; and then cap the sample under flowing water.
We chose our five main sample locations for geographic diversity and the availability of partners to help us collect the samples: Jakarta, New Delhi, Kampala, Beirut, and Quito. Tap water samples from Europe and the United States were less geographically concentrated than specimens from these five cities. The numbered samples were shipped to the University of Minnesota without information that would identify their source; our researcher didn’t know whose water she was testing. Respondents completed questionnaires about their location and habits of water use. These were sent directly to us at Orb Media.
The samples were handled with care. Here’s researcher Mary Kosuth describing the laboratory process:
“The ubiquity of synthetic polymers, especially airborne fibers, requires fastidious lab habits. In order to reduce potential sources of contamination during the procedure, all glassware was covered with a watch glass when not in use and washed thoroughly between trials. Work occurred in a laminar airflow cabinet and the workspace was wiped down every week. Filters were inspected under a microscope prior to use. Filtration times were recorded so that the window of time for potential contamination is known.”
To further account for contamination, three different types of lab blanks were processed. First, the filtrate from each sample was filtered a second time through a new filter and cleaned glassware. These blanks, referred to as filtered blanks (n=159), were carried out to make sure each sample was filtered thoroughly. Additionally, lab blanks containing only deionized water were run once each day samples were processed. These blanks were called deionized blanks (n=30) and they were carried out to account for background lab contamination from atmospheric deposition, deionized water, and glassware. Finally, bottled blanks were run by filling two empty 500mL HDPE bottles with deionized water in the lab, just as the samples had been collected. The deionized and bottle blanks were processed in a manner identical to the tap water samples in order to account for polymer contamination, or background levels, that could be coming from the either the collection receptacle or testing environment.
Our tests revealed plastic fibers 100 microns or greater in size*. The tap water samples likely included fibers and particles smaller than that; however, available equipment allowed only for identification starting beginning at 100 microns. Researchers suggest that micrometer and nanometer-scale plastics may translocate from the gut to different organs when ingested by animals. For example, a 2017 study showing the presence of microplastics in sea salt noted that prior research has demonstrated how 20 micron polystyrene microspheres “accumulated in the gills and gut of zebrafish (Danio rerio), while 5 μm microbeads were incorporated into the gills and gut as well as liver” following consumption.
* The study on which this story was based has now been published in Plos One, a peer-reviewed scientific journal, which means that a group of outside experts has found its methods and conclusions to be sound. The Plos One article broadens its description of the fibers found in global tap water samples to include plastic and other man-made substances. In her May 16, 2017, lab report to Orb Media, principal investigator Mary Kosuth had identified the fibers as “plastic,” a synthetic polymer. However, in Plos One, Kosuth and co-authors Sherri Mason and Elizabeth Wattenberg use the term “anthropogenic,” or man-made, to describe these fibers. The authors say they opted for this distinction in Plos One because the fibers Kosuth found in global tap water samples were not confirmed as plastic with an infrared spectroscope. Since the Rose Bengal stain used in the study binds only to natural substances, they write, “it is logical to assume that the particles found are at least synthetic and most likely could be classified as microplastics, but as spectroscopic analyses such as Fourier Transform Infrared Spectroscopy (FTIR) are required in order to confirm this assumption, we use the more general term throughout this report.”
Here’s the big picture: We found microscopic plastic fibers in the water of nearly every location we tested.
The United States and Beirut provided the highest average number of samples containing microscopic plastic fibers, 94 percent.
However, the relatively small number of samples from each of the global locations makes regional comparisons only the beginning of an exploratory analysis. Across our experiment, 28 samples, or 19 percent, had no plastic fibers. Thirty-eight percent of our samples contained either zero fibers or one plastic fiber, which is within the margin of error for a sample that may have no plastic.
“Since this is the first global tap water survey of plastic pollution to have been completed, the results of this study serve as an initial glimpse at the consequences of human plastic use [and] disposal rather than a comprehensive assessment of global plastic contamination,” Kosuth wrote in her report to us. “These results call for further testing within and between regions.”
Take Europe, which had the lowest average number of samples containing plastic fibers, 72 percent. We tested samples from Slovakia (8), the United Kingdom (3), Germany (2), Switzerland (2), Ireland (1), France (1), and Italy (1). Given the small number of samples from Europe, and their uneven distribution, it would be inappropriate to use these findings to draw broad conclusions about water quality in individual countries. Our results demonstrate the need for further investigation.
“This research only scratches the surface, but it seems to be a very itchy one,” said Hussam Hawwa, CEO of the environmental resource consultancy Difaf, which collected Orb’s Lebanon samples.
Within our confirmation of microscopic plastic fibers in tap water, Orb’s survey included other interesting nuggets, including an apparent relationship between respondents’ confidence in their tap water and the number of fibers found in corresponding samples.
Fifty percent of our samples worldwide were from tap water participants used for drinking. The other 50 percent came from tap water residents considered unfit to drink straight from the tap, if at all. (The United Nations has explicitly recognized the human right to safe drinking water.)
There is a lot of variation between countries in the typical count of plastic fibers in our survey. There is additional variation based on whether or not participants viewed their tap water as safe to drink. However, across all countries, water that respondents considered fit to drink from the tap had significantly fewer plastic fibers (typically around 3.3 per liter, with a standard deviation of 5.7) than the tap water that was not considered appropriate to drink (typically around 4.6 fibers, with a standard deviation of 8.1).
Another nugget. The highest number of fibers recorded in our study was almost too close for comfort: A sample from the kitchen sink at Orb Media, in Washington, DC, revealed 34 microscopic plastic fibers. This result was all the more surprising because Orb’s offices are served by a whole-house water filter at the water main, and a reverse-osmosis filter at the tap. This implies that, in the case of this sample, the filters installed at our office may be emitting plastic fibers.
This is just one of several questions raised by our tap water survey, including the provenance of fibers in samples originating from a variety of global locations and water sources, methods that might be used to keep them out of drinking water, and the potential health effects of plastic fibers in drinking water and food.