New Study Reveals: A Single Litre of Bottled Water May Contain Up to 2.4 Lakh Plastic Particles

A litre of bottled water could contain about 2.4 lakh plastic pieces on average, according to a new study published in the journal Proceedings of the National Academy of Sciences. The researchers from Columbia University analysed three popular brands of bottled water sold in the US, measuring plastic particles down to 100 nanometres in size. They detected about 1.1-3.7 lakh plastic fragments in each litre, 90 per cent of which were nanoplastics and the rest microplastics.

Types and sources of plastics

The study also determined the type and shape of the plastics they found, targeting seven common ones for biomedical purposes. They found a common one, polyethylene terephthalate or PET, which is used to make water bottles. Another type of plastic they found was polyamide, a type of nylon, which was found in greater quantity than PET. The researchers said the nylon could have come from the plastic fibres that are supposed to purify the water before it gets bottled. Other common plastics they found were polystyrene, polyvinyl chloride and polymethyl methacrylate, all used in various industrial processes.

However, the seven plastic types the researchers searched for accounted for only about 10 per cent of all the nanoparticles they found in the bottled water samples. The researchers said they had no idea what the rest were. The results indicated “the complicated particle composition inside the seemingly simple water sample”, they wrote.

Implications and challenges

The study revealed that the amount of plastic particles in bottled water is about 10 to 100 times greater than previous estimates that mainly concerned plastics of larger sizes. While microplastics range from a micrometre to 5 millimetres, nanoplastics are smaller than a micrometre and are measured in billionths of a metre.

In recent years, microplastics have been documented to be present in soil, drinking water, food and even polar ice. Formed when larger plastics break down into progressively smaller bits, these plastics find their way into humans and other creatures, with potential effects on their health and ecosystem.

“Previously this was just a dark area, uncharted. Toxicity studies were just guessing what’s in there,” said study co-author Beizhan Yan, an environmental chemist at Columbia Climate School’s Lamont-Doherty Earth Observatory. “This opens a window where we can look into a world that was not exposed to us before,” he said.

The researchers developed a technique called stimulated Raman scattering microscopy which involved probing samples with two simultaneous lasers tuned to make specific molecules resonate. They then used algorithms to analyse and interpret the data.

The team is now going beyond bottled water. “There is a huge world of nanoplastics to be studied,” said study co-author Wei Min, a Columbia biophysicist and a co-inventor of the microscopy technique.

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