Microplastics were found in human lungs and blood. Then, they were found in the human heart. The kidneys, too, have been identified as having microplastics in its tissue. So, too, has the penis, the placenta and even breast milk.
There was shock, and no little horror, after the first few studies appeared to suggest microplastics, defined as pieces or fibres smaller than 5mm – as well as nanoplastics, which are even smaller particles – were not just accumulating in the local environment, but in human organs.
Now, more and more frequently, micro and nanoplastics are being found in almost every part of the body. But how exactly are they entering our bodies?
According to UCD’s Dr Junli Xu – assistant professor at the School of Biosystems and Food Engineering, who specifically researches the health implications of microplastics and nanoplastics – said there are three main pathways of transmission.
Ingestion is one of the most commonly cited ways in which these particles enter the human body, given microplastics are in salt, beer, fresh fruit and vegetables, as well as drinking water. And the use of some packaging materials like baby bottles and tea bags. So by using these, they will release microplastics and they can directly enter the human body,” she says.
“Another pathway is directly through inhalation. The indoor and outdoor air has microplastic pollution and one of the major sources are car tyres. Also, the artificial grass also releases a lot of microplastics in the air.”
Dr Xu said dermal contact – through creams and cosmetic products – is also a method of transmission, though this is considered a “a lower likelihood than inhalation and ingestion”.
Her lab in UCD recently looked at microplastics in a medical setting. “A lot of the plastic in medical devices, like IVs, also have great potential to transmit microplastics into the body. It’s most significant because they will enter the bloodstream,” she says.
“So basically if we ingest some particles that are small, there is a strong barrier, but if a microplastic enters the bloodstream it is free to circulate all over the human body, and it is free to accumulate in different organs.”
The automatic reaction to news that human beings now have plastic in them has largely been worry.
Prof John Boland, of the School of Chemistry at Trinity College Dublin and director of the Centre for Research on Adaptive Nanostructures and Nanodevices, says bodies are designed to ingest lots of particles and then excrete them.
However, very small particles – primarily nanoplastics – work their way around the body and stay there.
“The problem is when the particle size gets small, these particles can start going places. There are all sorts of barriers in your body membranes and small particles can pass through membranes,” he says.
Adding to this, Prof Boland said micro and nanoplastics also have chemical additives that seek to make the product resistant to degradation. But they are particularly harmful to people.
“These additives can be quite toxic. There was a thing called BPA, that has been removed from many plastics, but that was a well-known chemical additive that was put into lots of materials. But there are many, many, many more. There are probably around 500 chemical additives that go on to plastics. And there’s not that much control over it,” he adds.
Earlier this year, it emerged the presence of plastics in people can have an impact on the way in which the human body operates.
A study, by Italian researchers and published in the New England Journal of Medicine, found heart disease patients with microplastics in the blood vessels on either side of their neck, which deliver blood from the heart to the brain and head, were twice as likely to suffer a heart attack or stroke.
These patients were also more likely to die over the next three years than people who had no microplastics in their carotid arteries, the major blood vessels that provide blood supply to the brain. Prof Boland says the findings of the study was one of the “scariest” things he has read in this area.
“When they removed plaque from arteries, in almost 60 per cent of those patients, the plaque they removed was full of micro and nanoplastics. This is because the plastic somehow got into the blood,” he says.
“And in fact, the Italian study also showed these patients who had this had very severe cardiovascular risks. These patients were functioning much less efficiently than they should be for patients of their age.”
But research into the implications of micro and nanoplastics on health is still at the very early stages, with researchers not wanting to “jump the gun”, Prof Boland says.
Exposure to infants is 10 times higher compared to adults. And supposedly they are more vulnerable. When babies are born they are surrounded by plastic products
Dr Xu said the research on health outcomes due to the presence of microplastics is “inconclusive”.
“It’s basically because it’s not like other chemical hazards, microplastics are extremely complex. For some hazards like BPA, we know that the only determinant for toxicity is the dose. So the higher the dose, the higher the toxicity,” she says.
“But when it comes to microplastics, it’s totally different. There are so many types: polystyrene, polyethylene, polypropylene. We don’t know which ones are more toxic. And they have many different chemical properties, the size, shape, surface area. All of these things contribute to the toxicity. So it is very difficult to perform an effective risk assessment.”
However, Dr Xu says while there are questions remaining about what exactly the health implications are to the growing prevalence of microplastics in humans, there is certainty around the inevitability of their manifestation.
“Scientists agree that it is not a question of if but when the adverse health impacts of microplastics will become apparent. These microplastics are not supposed to be in humans,” she adds.
“The situations will get worse before they get better. The amount of microplastics in the human body is anticipated to increase.”
And this is particularly true for the younger generation. Not only are they being exposed to a higher level of plastic pollutants, but they are also more vulnerable to pollution, Dr Xu says.
“Exposure to infants is 10 times higher compared to adults. And supposedly they are more vulnerable. When babies are born they are surrounded by plastic products. Everything is plastic: the toys, the chewing toys, the baby bottles, everything.”
But what exactly can people do to protect themselves from potentially catastrophic health outcomes, when plastic is, quite simply, everywhere? Well, there are a number of small actions that can be taken to minimise plastic pollution, the researchers say.
Recycling is one such option, according to Dr Xu, though she believes the pollution of bodies by plastic is “kind of inevitable”.
“Of course people can choose different lifestyles and use less plastic products or recycle to reduce the microplastics but it is always good to recycle as it will reduce microplastics entering the environment,” she adds.
According to Prof Boland, the way in which the public prepare and store food is a very important area when it comes to minimising plastic transmission to humans.
“Many people use plastic containers for storing food so we take it out of the fridge and put it into the microwave to heat it up, but that’s an absolute disaster. The actual microwave, together with steam and water, creates copious amounts of micro and nanoplastics,” he says.
“You think it’s great using the same container over and over again, but you’ve probably noticed if you look at the inside of a container, it starts getting rough and that’s because you’re losing material all the time.”
[ Invisible but everywhere – the growing spread of microplasticsOpens in new window ]
Prof Boland and his team in Trinity recently published research on how baby bottles can release plastic particles.
“One of the challenges is that the sterilisation process, which you have to do to clean a bottle, is the biggest cause of release of microplastics because you’re using scalding hot water. And that creates all levels of particles,” he says.
Switching to glass variations is one way of reducing this, he said, or removing the food from the plastic containers before heating them up is another one.
There are also steps the industry can take. His research team identified kettles emitting a large number of microplastics, but the coating that emerges from copper actually prevents the release of these particles.
“The brown [on the inside of a kettle] is from the water, from the copper pipes. Every time you boil your kettle you make copper oxide which covers the inside of your kettle and protects you from the release of plastics of any kind,” he says.
“We’ve shown there are ways to prevent the release of nanoplastics by coating it. But we just need industry to do it.”
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