Scientists say the average bottle of water contains 240 000 pieces of cancer-causing nanoplastics – 100 times more than previously thought, and a fact likely to shock those who choose bottled over tap water, believing it’s safer.
The recent research found hundreds of thousands of toxic microscopic plastic particles in the water, which scientists fear might accumulate in your vital organs with unknown health implications.
Nanoplastics have already been linked to cancer, fertility problems and birth defects.
Daily Mail reports that using the most advanced laser scanning techniques, the scientists found an average of 240 000 plastic particles in a one-litre bottle of water, compared with 5.5 per one litre of tap water.
The University of Columbia researchers had tested three popular brands of bottled water sold in the US and analysed the plastic particles down to just 100 nanometres in size.
The particles – nanoplastics – are much smaller than the microplastics previously detected in bottled water, but are considered potentially toxic because they are so small they can enter directly into blood cells and the brain.
These microscopic particles carry phthalates – chemicals that make plastics more durable, flexible, and longer lasting.
Phthalate exposure is attributed to 100 000 premature deaths in the US each year.
The chemicals are known to interfere with hormone production in the body, and have been linked to developmental, reproductive, brain, immune and other problems, according to the National Institute of Environmental Health Sciences.
The highest estimates found 370 000 particles.
The team used a new technique called Stimulated Raman Scattering (SRS) microscopy, recently invented by one of the paper’s co-authors.
The method probes bottles with two lasers tuned to make specific molecules resonate, and a computer algorithm determines their origin.
The results showed that nanoparticles made up 90% of these molecules – and 10% were microplastics.
One common type found of nanoparticle was polyethylene terephthalate or PET.
Study co-author Professor Beizhan Yan, an environmental chemist at Columbia, said: “This was not surprising, since many water bottles are made of that.”
It probably gets into the water as bits slough off when the bottle is squeezed or gets exposed to heat, he said.
Another plastic particle found in bottles of water, and one which outnumbered PET, was polyamide, a type of nylon.
“Ironically,” said Yan, “this probably comes from plastic filters used to supposedly purify the water before it is bottled.”
The other common plastics found included polystyrene, polyvinyl chloride (PVC), and polymethyl methacrylate, all of which are used in various industrial processes.
However, the researchers found it “disturbing” that these named plastics accounted for only around 10% of all the nanoparticles found in the samples. They have no idea what the rest are.
Biophysicist and study co-author Wei Min said the research opens up a new area in science, adding: “Previously this was just a dark area, uncharted. The study of nanoplastics matters because the smaller things are, the more easily they can get inside us.”
Study details
Rapid single-particle chemical imaging of nanoplastics by SRS microscopy
Naixin Qian, Xin Gao, Xiaoqi Lang, Beizhan Yan, Wei Min, et al.
Published in PNAS on 8 January 2024
Abstract
Plastics are now omnipresent in our daily lives. The existence of microplastics (1 µm to 5mm in length) and possibly even nanoplastics (<1 μm) has recently raised health concerns. In particular, nanoplastics are believed to be more toxic since their smaller size renders them much more amenable, compared to microplastics, to enter the human body. However, detecting nanoplastics imposes tremendous analytical challenges on both the nano-level sensitivity and the plastic-identifying specificity, leading to a knowledge gap in this mysterious nanoworld surrounding us. To address these challenges, we developed a hyperspectral stimulated Raman scattering (SRS) imaging platform with an automated plastic identification algorithm that allows micro-nano plastic analysis at the single-particle level with high chemical specificity and throughput. We first validated the sensitivity enhancement of the narrow band of SRS to enable high-speed single nanoplastic detection below 100 nm. We then devised a data-driven spectral matching algorithm to address spectral identification challenges imposed by sensitive narrow-band hyperspectral imaging and achieve robust determination of common plastic polymers. With the established technique, we studied the micro-nano plastics from bottled water as a model system. We successfully detected and identified nanoplastics from major plastic types. Micro-nano plastics concentrations were estimated to be about 2.4 ± 1.3 × 105 particles per liter of bottled water, about 90% of which are nanoplastics. This is orders of magnitude more than the microplastic abundance reported previously in bottled water. High-throughput single-particle counting revealed extraordinary particle heterogeneity and nonorthogonality between plastic composition and morphologies; the resulting multidimensional profiling sheds light on the science of nanoplastics.
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