Some bottled water worse than tap for microplastics, study shows

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Some bottled water worse than tap for microplastics, study shows

Insights could inform future efforts to remove plastic from environment

Some brands of bottled water contain significantly higher levels of microplastics than tap water, according to new research by scientists who have developed a novel method for detecting these tiny particles.

The result of a global buildup in plastic pollution, microplastics and nanoplastics are small synthetic particles produced when plastic products are used or degrade. These plastic fragments are found nearly everywhere in the environment, including the nation's waterways.

To better understand the concentration levels in a segment of the U.S. water supply, scientists analyzed water samples from four treatment plants near Lake Erie and six different brands of bottled water. Their results showed that bottled water contained three times as many nanoplastic particles as the treated drinking water, said Megan Jamison Hart, lead author of the study and a PhD candidate in environmental sciences at The Ohio State University.

"We can make educated choices to try and reduce our daily exposure to these harmful chemicals," said Hart. "For the average person who is thirsty and wants a drink, the best way to do that would be drinking it straight out of the tap rather than grabbing pre-bottled water."

While previous research evaluated the presence of microplastics in different drinking water sources few have centered on nanoplastics, likely because their extremely small size makes them a challenge to study, said Hart. Using a combination of imaging (scanning electron microscopy) and chemical identification (optical photothermal infrared spectroscopy) techniques allowed the team to detect and identify particles down to their smallest parts.

The study was recently published in the journal Science of The Total Environment.

Although the extent of microplastics' effect on human health is still unclear, many experts suggest their presence may be detrimental to our well-being in the long term, as smaller plastic pieces, called nanoplastics, are more likely to cross vital biological barriersin the body.

"While we don't really fully understand the human health risks associated with nanoplastic exposure, it's still better to try and mitigate that risk because evidence indicates that they do cause problems, even if we're not fully aware of what those are yet," said Hart.

During their experiments, researchers found that the most common plastics in the bottled water came from the bottled water packaging, which they expected, but the source of the plastics in the drinking water is still unclear. Over 50% of all the particles detected were nanoplastics, demonstrating how pervasive these tiny chemicals can be, even in drinking water.

These details confirm that nanoplastics are a significant component of the world's overall amount of microplastic contamination and scientists likely underestimate the true scope of their environmental threat, said John Lenhart, senior author of the study and a professor of environmental engineering at Ohio State.

"The concentrations we saw were higher than anticipated, which, unlike prior studies, we were able to attribute to the inclusion of the nanoplastics," said Lenhart. "That emphasis validates a lot of the information we've learned."

Incorporating nanoplastics into this study's measurements may lead to additional insights down the line, including whether the team's analytical techniques could also be utilized to evaluate which treatment processes work best at removing these silent invadersfrom the environment.

"By understanding the basic composition of the materials in water and the reactions important for controlling that composition, we can make better design decisions for future treatment or for remediation," said Lenhart. "That's why analyses like these are so promising."

The study was supported by the U.S. National Oceanic and Atmospheric Administration through its Ohio Sea Grant College Program and the National Science Foundation.

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