Plastic contamination is rampant in bottled water. This was the disturbing conclusion of a recent study, published in Frontiers in Chemistry, that analyzed samples from 259 bottles of water sold across the globe.

Researchers from the State University of New York at Fredonia found that 93 percent of the samples contained small, often microscopic, particles of plastic called microplastics. The team classified 65 percent of these microplastics as fragments, noting that some of them were visible to the naked eye.

Bottled water contains microplastics

The team gathered bottled water samples from 11 different global and national brands in countries chosen for their large populations or their high consumption of bottled water. These countries included the U.S., China, Brazil, India, Indonesia, Mexico, Lebanon, Kenya and Thailand.

During testing, samples from each brand demonstrated different microplastic concentrations, likely due to factors that might affect the occurrence of plastic particles, such as the manufacturing process itself. Nonetheless, the team found an average of 325 microplastic particles per liter of bottled water across all the brands tested.

To screen the samples for microscopic plastic particles, the researchers used a Nile red dye solution that binds to plastic. It also fluoresces under infrared light, rendering the plastic particles more visible under the microscope.

Upon examination, the team found that samples of the brand Nestle Pure Life had the largest average concentration of microplastics out of all the brands tested. One sample from this brand was found to contain a staggering excess of 10,000 microplastic particles per liter of water. Also, only 17 of the 259 samples tested did not contain microplastics.

These results generated headlines in 2018, prompting the World Health Organization (WHO) to investigate the potential impact of microplastics on human health. Back then, the report had not been submitted for publication in a scientific journal. Instead, it had been released by journalists from the nonprofit organization Orb Media.

The impact of microplastic pollution

The problem of microplastic contamination is far bigger than bottled water. When improperly disposed of, large pieces of plastic, called macroplastic, can eventually break down into smaller particles that become more difficult to detect and eliminate.

A recent study published in Nature Geoscience found traces of microplastic fragments and fibers moving through the air of the remote Pyrenees Mountains in France. This finding underscores the fact that microplastics are beginning to spread to non-urban settings that might not have had plastics in the first place.

But more concerning still is the result of a small 2018 study that analyzed the stool samples of eight participants from Europe, Japan and Russia. Each sample had been found to contain microplastic particles. Based on their findings, the researchers estimated that more than 50 percent of the world’s population might have microplastics in their stool.

If so, this comes as no surprise. Traces of microplastic fragments and fibers are becoming increasingly common in fish, shellfish and other marine animals due to plastic pollution. These particles can then end up in the human gastrointestinal tracts upon consumption of the contaminated fish.