When we think of the devastating toll that plastic pollution can have, it is usually images of turtles caught in single-use bags or piles of plastic bottles in landfill that we conjure up — for most of us, it is an environmental problem.
But there is emerging evidence that plastic waste could become a health issue, too.
The problem lies with plastic as it breaks down into tiny particles — so-called microplastics, which are 5 mm in length (the size of a lentil), or less.
These tiny particles are everywhere: they are produced from the breakdown of bags and bottles, the wear and tear of the soles on our shoes as we walk, and the tyres on our cars as we drive.
Even putting on a load of laundry generates hundreds of thousands of microplastic fibres (from fabrics such as nylon, acrylic and polyester).
What’s more, mask wearing may increase our exposure, says Alex McGoran, a microplastics researcher at Royal Holloway, University of London and the Natural History Museum. ‘Single-use face masks likely shed microplastic fibres into the air around us. But the benefit we gain from wearing them probably outweighs the cons of potential microfibre inhalation.’
These tiny particles are in our water, food and on surfaces we touch — and we are only just understanding their impact.
While our bodies are thought to clear some of the microplastics that build up inside us, according to a 2018 review by King’s College London, newer research suggests it’s possible for microplastics to pass from the airway or gut into the blood and to our organs. In theory, the plastic could then cause damaging inflammation or leach harmful chemicals.
In one of the latest studies, Italian scientists found microplastics in human placentas for the first time, which could affect foetal health and development.
The findings, published last month in the journal Environment International, led the researchers to suggest women are giving birth to ‘cyborg babies’ — and British experts now warn that while we don’t know the exact impact this plastic can have, the fact it makes it to the placenta is less than reassuring.
As Alex McGoran explains, microplastics are everywhere: ‘We hear about fish with plastic in them and the perception is that most of the microplastics we consume come from seafood.
‘But we are surrounded by plastic. For instance, at home, you might be walking on an artificial carpet, closing curtains made from polyester and sitting on a chair with an artificial cushion — all of these shed fibres into the air which we can then breathe in.’
A 2018 study from Heriot-Watt and Plymouth universities calculated that the average Briton will swallow up to 68,415 pieces of microplastic a year from dust.
And our diets (microplastics have been detected in everything from beer to sea salt and honey) provide another 52,000 or so of these particles per year, according to the journal Environmental Science & Technology in 2019.
But what, if anything, could be the consequences of plastic particles building up in our bodies?
In a 2019 study by the University Medical Centre in Utrecht, scientists wanted to investigate how human immune cells deal with microplastics. They put the cells in a petri dish with microplastics and found that while our immune cells recognised and engulfed the plastic particles, they died as a result.
This cell death can be linked with potentially harmful inflammation. Research is ongoing to see if this happens in animals and humans.
Meanwhile, there are concerns that some microplastics are small enough to get into our bloodstream and organs.
A 2018 study analysed stool samples from eight people from Europe, Japan and Russia and found that plastics, including polypropylene (commonly used in food containers and packaging) and polyethylene terephthalate (a polyester used in clothing and food packaging), were present in human stools, showing that microplastics could get through the human gastrointestinal tract.
Plastic in the gut could affect the digestive system’s immune response or aid the transfer of chemicals and pathogens, the researchers said, adding that this may have implications for ‘patients with gastrointestinal diseases’.
In a 2018 animal study in the journal Environmental Science & Technology, Richard Thompson, a marine biologist at the University of Plymouth, who first coined the term microplastics in 2004, showed pieces of plastic can pass from the gut into the circulatory system.
He told Good Health: ‘If we have shown in scallops that small pieces can pass from the gut to the circulatory system, it’s likely that could occur with humans, too. But that doesn’t necessarily tell you it is harmful.’
In the recent Italian study, 12 plastic pieces were detected in four placentas that were donated after birth. Three of these pieces were recognised as polypropylene, while the other pieces appeared to be plastic particles from ‘man-made coatings, paints, adhesives, plasters and cosmetics’.
The women had healthy pregnancies but the authors said that, given the crucial role of the placenta, the ‘presence of plastic particles is of great concern’.