An international team of researchers has developed a breakthrough microscopic technique that can detect minute particles of plastic in bottled water that can pass into human blood, cells and the placenta. (Photo by Hendrik Schmidt/picture alliance via Getty Images)
An international team of researchers has developed a breakthrough microscopic technique that can detect minute particles of plastic in bottled water that can pass into human blood, cells and the placenta with unknown health effects.
In their study, the researchers from Rutgers and Columbia universities counted and identified particles in three popular brands of bottled water in the United States.
They found that, on average, a litre of water contained roughly 240 000 detectable plastic fragments. This is 10 to 100 times greater than previous estimates based mainly on larger sizes of plastic found in the water.
“Recently we, as scientists, have been able to visualise and identify large plastic particles in human tissues, including the lung and placenta,” co-author Phoebe Stapleton, professor of pharmacology and toxicology at Rutgers University, said in a statement. “This methodology opens the door to evaluate smaller particles with greater toxicological potential and concern.” The study was recently published in the journal Proceedings of the National Academy of Sciences,
The researchers noted that microplastics are showing up nearly everywhere on Earth —from polar ice to soil and in drinking water and food — with little known about how they affect the ecosystem. These particles are formed when plastics break down into progressively smaller bits and are consumed by humans and other creatures.
Microplastics are defined as fragments ranging from 5mm down to one micrometre, which is one millionth of a metre. The far smaller nanoplastics — particles below one micrometre and measured in billionths of a metre — are so tiny that they can pass through environmental filters and biological barriers, including the lungs and intestines.
From there, they can travel to organs such as the heart, brain and placenta. They can invade individual cells and cross through the placenta to the bodies of foetuses.
Revolutionary technique
The researchers used a technique called stimulated Raman scattering microscopy, which was co-invented by Wei Min, a Columbia biophysicist and the co-author of the study. It involves probing samples with two simultaneous lasers that are tuned to make specific molecules resonate.
They created a data-driven algorithm to interpret the results of targeting seven common plastics — polyamide 66, polypropylene, polyethylene, polymethyl methacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate (PET).
Stapleton said this technique is revolutionary in the field. “It not only allows us to detect nanoplastics but also to identify the polymer type.”
The researchers declined to name the bottled water brands they tested and analysed plastic particles down to 100 nanometers in size. They spotted 110 000 to 370 000 particles in each litre, 90% of which were nanoplastics, while the rest were microplastics.
They also determined which of the seven specific plastics they were and charted their shapes — qualities that could be valuable in biomedical research. One common plastic is PET, which is used in water bottles and condiment packaging. The other is polyamide, a type of nylon.
The seven types of plastic the researchers searched for accounted for about 10% of all the nanoparticles they found in samples. But the researchers have no idea what the rest are.
If they are all nanoplastics, that means they could number in the tens of millions of particles per litre. But they could be almost anything, “indicating the complicated particle composition inside the seemingly simple water sample”, the authors noted in their study. “The common existence of natural organic matter certainly requires prudent distinguishment.”
Alarming concerns
On the significance of their study, the researchers said that micro-nano plastics originating from the prevalent usage of plastics have raised “increasingly alarming concerns” worldwide.
“However, there remains a fundamental knowledge gap on nanoplastics because of the lack of effective analytical techniques. This study developed a powerful optical imaging technique for rapid analysis of nanoplastics with unprecedented sensitivity and specificity.
“As a demonstration, micro-nano plastics in bottled water are analysed with multidimensional profiling of individual plastic particles. Quantification suggests more than 105 particles in each litre of bottled water, the majority of which are nanoplastics. This study holds the promise to bridge the knowledge gap on plastic pollution at the nano level.”
Beizhan Yan, an environmental chemist at Columbia University’s Lamont-Doherty Earth Observatory and a co-author of the study, said this was previously a dark, uncharted area. Yan said previously, toxicity studies were based on guessing what’s in there but now a window is open to look at a world we haven’t been exposed to before.
‘No scientific consensus’
The International Bottled Water Association said in a statement that the new study used bottled water to “apparently demonstrate a new method for nanoplastics analysis because of a lack of currently available methods”.
“This new method needs to be fully reviewed by the scientific community and more research needs to be done to develop standardised methods for measuring and quantifying nanoplastics in our environment … Therefore, media reports about these particles in drinking water do nothing more than unnecessarily scare consumers.”
The association said it is important to note that bottled water is just one of thousands of food and beverage products packaged in plastic containers. “Moreover, and perhaps even more important, nano- and microplastic particles are found in all aspects of our environment — soil, air, and water.”
It said that as there is no scientific evidence to suggest that nano and microplastic particles pose a health risk, the US Food and Drug Administration “has not issued any regulations concerning these substances in foods and beverages”.