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Why we should worry about plastic in the air
PROFESSOR FRANK KELLY: Why we should worry about plastic in the air
History is littered with examples of developments which seemed a great idea at the time but have subsequently been discovered to have unfortunate consequences for our health.
The list includes smoking cigarettes, putting lead in petrol and using asbestos in building materials. And in years to come, we may well look back and wonder why we ever tolerated the presence of plastic in everything from water bottles to carrier bags.
We already know that microplastics consumed by fish and other marine creatures can find their way into the human food chain. But this latest Mail investigation adds to a growing body of evidence that demonstrates they are contained in the very air that we breathe.
Investigation adds to a growing body of evidence that microplastics have contaminated the air that we breathe
This is an issue I have been worried about for some time. In 2016, I presented my concerns over airborne microplastics to Parliament’s environmental audit committee. The concerns were based on two possible routes of transmission.
Global production of plastic exceeds 320million tons, around 40 per cent of which goes into single-use packaging. A substantial proportion of that makes its way into our oceans where it becomes brittle under the sun’s rays and breaks into microscopically small fragments.
To give you an idea of how tiny they are, the diameter of a human hair is 50 micrometers (millionths of a metre). A particle of microplastic is less than ten micrometers and can easily be swept into the air and transported great distances by the wind.
Until they were banned at the beginning of this year a major source of inhalable microplastics were the microbeads previously used as exfoliants in cosmetics such as face scrubs.
While these may be on the way out, household effluent still contains the minuscule fibres released when clothes made of popular materials such as polyester and nylon are washed.
Swept away with the household’s waste water, they contribute to the slurry that sewage farms spread over agricultural land. As this dries out, the microplastics are released into the atmosphere and – just as is happening in our oceans – are carried many miles by the wind.
When I appeared before the parliamentary committee, there was no firm evidence that any microplastics had found their way from seas and sewage farms into our towns and cities but it was not long in coming.
Later that year, a team of French researchers placed a container full of water on top of a university building in Paris and left it exposed to the air for about a week.
Careful analysis revealed a wide array of microplastics that can only have been deposited in the water by the surrounding atmosphere.
We have since followed up this work at King’s College London where we operate the London Air Quality Network, with more than 100 monitoring stations measuring pollution from traffic and other sources in the capital’s 33 boroughs.
Microplastics seem to be present in the atmosphere in surprisingly high numbers, although it is difficult to differentiate between them
Since 2016 we have also been looking out for microplastics and, although we can’t yet give reliable indicators about their concentration, or what type of plastic they are, they seem to be present in the atmosphere in surprisingly high numbers.
So how concerned should we be? Although no definitive studies on the health effects have been conducted, one indication comes from the problems caused by the plastics used in hips and knee implants.
The erosion resulting from wear and tear of implants causes inflammation in surrounding tissues, leading to the death of cells and scarring.
It’s easy to surmise the damage such particles may inflict in the most sensitive recesses of our lungs, which is where they have been found in patients suffering from lung cancer.
Just to be clear, there is no evidence of a link between the microplastics and lung cancer. But these biopsies show us two disturbing characteristics of microplastics.
The first is that they are small enough to penetrate deep into the lungs, avoiding the usual methods of dislodging foreign bodies, including coughing and the actions of our mucous membranes. The second is that they exhibit very little deterioration, suggesting that they can persist in our bodies for a lifetime after exposure.
Apart from the possible effects of the microplastics themselves, another concern is that these tiny bullets entering the body act as carriers for a range of different chemicals added by manufacturers to give them properties such as malleability. Because these chemicals are not chemically bound to the plastic particles, they can leach out and transfer to surrounding tissue.
For example, the chemicals used to make all furniture and carpets fire-retardant, as is required by law, include a group known as polybrominated diphenyl ethers.
These have been associated with a number of serious health issues, with some shown to be carcinogenic if present in sufficient quantities.
Tyres are another source of airborne microplastics and these are laced with cadmium, a highly toxic metal which helps make them hard and durable but has been linked to lung cancer in those working in tyre manufacturing plants. As these examples suggest, the problem with microplastics may go far beyond ensuring that we dump less household waste in our seas.
Plastics are everywhere, and in our measurements at King’s College, we have been particularly struck by the high levels of clothing fibres in the atmosphere.
They are clearly not something you would want to breathe in, judging by the respiratory problems found in clothing industry workers who have inhaled ‘flock’ – microfibres thrown off during the manufacture of the materials we wear.
Symptoms of these workers have included coughing, wheezing, breathlessness and increased phlegm production. And although the levels of microplastics encountered in such factories are far greater than those in our everyday environment, this indicates their potential to trigger a number of undesirable bodily responses due to the ease with which they enter the lungs and their persistence once inhaled.
Far more research is needed to establish what problems may arise in ordinary homes. Only last week the World Health Organisation announced a review into the potential risks of plastics in bottled water after analysis of some of the world’s most popular brands found that more than 90 per cent contained microplastics, one theory being that the contamination resulted from fragments breaking off from the caps.
That WHO initiative is to be welcomed. But let’s not lose sight of the problem of airborne microplastics.
Are they poisoning or slowly killing us? And, if so, might they even explain the growing prevalence of conditions such as chronic obstructive lung disease and dementia?
It was once believed that our chances of developing these diseases were primarily down to genetic background – and this is partly true. But now it is thought that at least 70 per cent can be explained by our environment in the widest sense of the word: the food we eat, the chemicals we come into contact with and, of course, the air we breathe.
Microplastics are a potential piece of that jigsaw. Whether it’s a big piece or a small piece remains to be seen and while it would be wrong to be alarmist about airborne plastics, we have every right to be extremely wary.