A new study published in the Proceedings of the National Academy of Sciences (PNAS) found that the average bottle of water contains nearly a quarter million fragments of “nanoplastics”. These are different from ‘microplastics’ as they are approximately the size of viruses, hence small enough to cause harm to how human cells operate.
“We know microplastics are always in the environment,” Beizhan Yan of Columbia University told US-based newspaper The Hill and pointed out that they are large and easy to measure and can be viewed using an electron microscope.
But the team that released the findings are more concerned with nanoplastics, which are particles thousands of times smaller and measurable in billionths of a metre. “Because the smaller the particle size, they are easy to get into the human bodies and then cross different barriers,” Yan said, adding that smaller particles mean bigger danger.
“(These) can cross into the blood, and then can cross the different barriers to get into the cells (and cause) them to malfunction,” Yan said.
A separate study released by The Lancet in December showed that nanoplastics and microplastics can dangerously impact the functioning of the human body. “(It) oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disrupted microbial metabolic pathways, abnormal organ development, and carcinogenicity,” the researchers who authored the study said.
But the PNAS study revealed grim facts about the type of plastics entering our body. The researchers who authored the study used a new method of laser imaging to find out what plastic polymers people are actually ingesting and the amount to understand the damaging effects.
They identified plastics of far smaller sizes than ever before. They ran water from three common brands through a filter that was extremely fine-grained and trapped those particles which are measurable on a scale of billionths of a metre.
However, they found just 10% of the total nanoparticles the scientists discovered and they found bits of microscopic clays, metals and the black carbon from fires and plastics so degraded that the imaging technology couldn’t pick them up, all of which are yet to be identified.
The authors drew comparisons between a particle of sand inside an engine and the human body to point out how harmful these particles can be as they are so small that they can get inside and disrupt functioning of human cells.
Dangerous Chemistry
The authors were particularly concerned about the chemical structure of plastics. Citing the examples of petrochemicals, the authors said that plastics that are similar to the chemistry of living creatures can mimic key biological processes and could imitate the chemical messengers in our body that help perform a wide range of bodily functions.
They found a wide range of plastics in the bottles, but five types were predominant – starting with polyethylene terephthalate (PET). The findings caused concern because PET is thought to be generally safe and it makes up the structure of the bottles themselves.
The findings also revealed that the water in the bottles had a wide array of potentially dangerous nanoplastics which were not present in the bottles which pointed to yet to be found sources of environmental contamination.
They found nylon which breaks down into toxic monomers as it degrades. They identified polystyrene, commonly known as styrofoam which can break down into the suspected carcinogen styrene. They also found polyvinyl chloride (PVC), which can contain harmful additives such as lead or phthalates and has been linked to disruptions in the nervous or endocrine systems.
Co-author Naixin Qian of Columbia University told the US-based newspaper that they also came across an ‘ironic finding’ – plastic compounds in the water that matched the primary material in reverse-osmosis filters. This could mean that plastics may have leached into water during the process of filtration. Qian added that PVC and polystyrene seemed to have entered the plastic bottles with the “source water” that filled them. The source water, according to the US Environmental Protection Agency (EPA), could have been contaminated through aerosolized plastic gases that plastic factories emit which make their way into air, and therefore rain and water.
Health Risks
The researchers were concerned about the severe health risks these nanoplastics posed. They found out that both the very young and very old remain particularly vulnerable.
Yan said that these particles are small enough to cross the blood-brain barrier and could lead to neural degeneration in the elderly for whom the barrier is “looser”. Nanoplastics may also lead to cell damage and are small enough to cross the placenta into the generally sheltered environment of the womb.
What effects it may have on the foetus are yet to be found.
Nanoplastics can enter inside the umbilical veins that pull blood and waste products back from an embryo. This can hamper cellular processes that help dispose of cellular debris.
This poses serious threats to the embryonic nervous system, kidney and reproductive cells and also threatens the normal growth of the foetus’s heart.
These nanoplastics may make it harder for the cells in foetal brain tissues to stay alive.
The researchers also said that the human digestive system is prone to impact as plastics are likely to enter the human body through drinking water. Scientists said that PET interferes with key microbial communities in the human gut. These encourage harmful bacteria to grow and suppress beneficial bacteria.
Experiments carried out on mice found that micro- and nanoplastics lead to cell death in the lining of the intestine and increase inflammation in the gut. If they reach the bloodstream they could also lead to heart disease.
Rats fed water with Styrofoam nanoparticles experienced heart issues, as the particles accumulated and caused swelling, stopping heart function and cell death, as per a study conducted in 2021. Tests conducted in a petri dish found that nanoparticles could destroy human red blood cells but these findings could not be replicated inside actual blood.
The report by the newspaper said that the risks of nanoplastics currently remain a matter of conjecture. They said that these particles can be very toxic to cells at high doses but it is yet to be found what happens at the levels that ordinary public are actually exposed to.
Raman Effect
The scientists are looking forward to understanding that by closing a gap in technology which will allow a reliable way to identify nanoparticles in the environment.
Using Raman scattering, derived from the studies conducted by Indian scientist CV Raman, scientists can hit an unknown plastic particle with a laser beam and decode the frequency of the light that bounces back to tell what plastic polymer is inside. It will allow them to identify specific nanoplastics in soils, the air and human tissue.
“Those different chemical bonds have different, essentially intrinsic energy. And we can use lasers to interrogate that energy and detect the interaction between the laser and that part of the chemical bonds,” co-author of the research Wei Min was quoted as saying. Min said it will allow researchers to distinguish different chemical bonds, and therefore different types of polymers.
Qian told the newspaper that they are yet to have enough information on how nanoplastics levels found in bottles compare with levels in tap water around the nation and said toxicologists can take the research forward to find out how the levels the team found in bottled water translate to impact on human health.
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