RTÉ Brainstorm | Why Fibre Is Not Always Good For Your Health

3 Sep 2019

Air quality and plastic pollution rarely (if ever) appear in the same written sentence even though separately they represent problems that every person interested in our environment knows about.

But a recent report on the distribution of microplastic fibres in snow samples, collected as far away as the Arctic, shows that we must start coupling the two together. Clearly these pollutants get transported to remote places like Greenland by being blown through the air on Earth's winds.

And that means on the way from here to there, the microscopically small threads can end up in our lungs. The most infamous microfibre is asbestos, which has been used to make objects heat resistant since ancient times and was taken up much later by various industries to prevent fires. Given our experiences with cigarette smoking, it will come as no surprise that the harmful health effects caused by asbestos were known by the manufacturers at a very early stage. The human outcomes are serious, with patients contracting lung cancer and cardiovascular disease; so the industry is highly regulated now. Asbestos is a natural mineral and is mined just like coal. The nuggets can be readily separated into thin microfibres ranging in length from about 250 micron (two to three human hair-widths) down to 3 microns or less (about thirty can sit side by side in the width of a hair). They are not very thick and can reach down to 0.05 micron (about 1000 in a hair’s breadth).

Microplastic fibres come from manufactured sources like car tyres, cosmetics, clothing and packaging. We normally think of plastics ending up in the oceans or on the land. But now they have been shown to reach the remotest region of the planet a penny has dropped and we now realise that they must be found everywhere in the air we breathe. The question is: can we monitor them on the long journeys they make round the world through our atmosphere? Airborne particulate solids often come from road transport and domestic solid fuel burning. They are generally crudely characterised by their size and overall mass per volume because they are the only features that EU and national legislation requires currently. Other important variables, like numbers present as a function of size and individual chemical composition, are not currently reported to bodies like the Environmental Protection Agency.

However, there are specialized, expensive research techniques like ATOFMS (don’t ask) that can characterise the chemical composition of airborne pollutant particles in real-time as a function of size. In the data analyses the solids are treated as small spheres (e.g. PM2.5, meaning 2.5 microns in diameter or less) although it is understood that they are much more irregular in shape than that. Small biological particles like airborne fungal spores can also be monitored but by using optical scattering and fluorescent light detection. Again, they are treated as small spheres with some measure available to estimate how off-spherical they are.

In contrast, non-mineral, microplastic fibres are thin and distinctly non-spherical. These are never characterised in ambient outdoor or indoor air samples to my knowledge, although the technology is potentially available because of occupational concerns about detecting asbestos. Hence some instrumental techniques have emerged recently to quantify the presence of airborne asbestos fibres in real-time. One of them is called ALERT (Asbestos Location Equipment in Real Time) and uses a cheap laser as the basis to distinguish between mineral and non-mineral microfibres in the air.

Polyester is not asbestos of course. So would plastic microfibres have the same adverse health effects on our hearts and lung as asbestos ones cause? Well, a twenty-year-old epidemiological study suggests they could, or would. The results show that samples taken from patients with lung tumours did contain microplastic pollutants and were found in almost 100% of specimens presenting malignant cancer cells. It looks like atmospheric research scientists, the EU and national governments are going to have to show some moral fibre in developing and deploying instrumentation that can help here.

Maybe the petrochemical industry will sponsor the programme. Maybe not.

Article written by Prof. John Sodeau for RTÉ Brainstorm.