Understanding plastic pollution – What is the contribution of our clothes?

PLOS ONE is thrilled to present a curated new collection – Recent Advances in Understanding Plastic Pollution. This global challenge may not have been the most prominent in the media over the past two years, but researchers, governments, volunteers and the public have all worked hard to make sure it’s easier than ever to be part of the movement to reduce plastic pollution. Many of us will by now be used to receiving take-out food in paper bags or boxes and being equipped with wooden forks and spoons instead of the traditional plastic ones. The PLOS ONE research community working on plastic pollution has been busy reporting new findings on identifying the prevalence of microplastics in various organisms and habitats, understanding how members of the public understand recycling and bioplastics, and how clothes shed microfibers during washing and drying. You can find out more about it all in our new curated collection.

In this first installment of our Q&A with the authors of this collection, we talk to some of our researchers working on how clothes can contribute to microfiber pollution during washing and drying.

Neil Lant, Researcher, Procter & Gamble

Dr. Neil Lant joined Procter & Gamble’s Newcastle Innovation Center in 1997 after earning a degree in chemistry and a doctorate in bioorganic chemistry. For the past 25 years he has worked in the development of home care and textile products for all regions of the world, with a focus on the application of new enzyme technology to improve performance and durability. products, resulting in more than 150 family patent applications. He also directs P&G’s microfiber research program, as part of his broader interests in the role of fabric care products in improving the durability of textiles.

Article by Neil Lant in this curated collection: Lant NJ, Defaye MMA, Smith AJ, Kechi-Okafor C, Dean JR, Sheridan KJ (2022) The Impact of Fabric Conditioning Products and Lint Filter Pore Size on air pollution by microfibers resulting from machine drying. PLoS ONE 17(4): e0265912. https://doi.org/10.1371/journal.pone.0265912

PLOS: Your engineered microfiber pulls away from clothes under various wash and dry conditions. You made a distinction between European and North American washing routines. What is the main difference between these? How do they differ from those in other parts of the world that have not been studied?

NL: The washing machines used in Europe are almost exclusively front-loading washing machines with a washing water volume of around 13 litres. However, in North America, several very different types of devices are used, broken down into three types: (i) front-end loaders which are essentially larger versions of European machines, (ii) traditional top-loading machines which have a large water volume of approximately 64 liters and (iii) high-efficiency top-loading machines with a water volume of approximately 32 liters. We have found that the release of microfibers is influenced by many factors, but our previous publications were the first to recognize that the water volume to fabric weight ratio was particularly important, with high water to fabric ratios causing the levels of highest release. For this reason, we run tests on European and North American top-loading machines to verify that the same trends are observed under very different conditions. Other types of appliances are used in different parts of the world and many consumers still wash by hand, but European and North American washing machines are good representatives of those used in markets where the dryer is current, because in this article we are mainly interested in the release of microfibers during the drying step.

PLOS: You mention in this study that the only real solution to microfiber loss might be to design a completely different type of dryer. What should be the main differences, and how close are we to being able to develop something like this?

NL: The study focused on airborne microfiber pollution from vented clothes dryers that have an air duct to the outside of the building, which is the largest type of clothes dryer in America North with more than 95% of the market. The release of airborne microfibers can be eliminated by improving the removal of fibers from that air stream (e.g. using the cyclonic filtration process used in many vacuum cleaners) or by switching to clothes dryers fully sealed condensing units that collect all fibers and moisture in the unit. The only problem with the latter is that the fibers can end up in condensed water or on the condenser which is usually washed in a sink, risking solving an air pollution problem by increasing water pollution! This suggests that we may need to redesign all tumble dryers to ensure that all fibers can be collected and disposed of in household waste, with no possibility of the fibers being released into the air or water.

Chimdia Kechi-Okafor, co-author of this study in PLOS ONE, inspect one of the filters used to better understand the loss of microfibers during tumble drying. Chimdia Kechi-Okafor is a PhD student in Fiber Evidence at Northumbria University.

PLOS: You have studied the fall of clothes during washing and drying. We also know that clothes lose microfibers when we wear them. Do we know how the release of microfibers for a certain garment differs during washing, drying and wearing?

NL: Forensic scientists have long known that fabrics shed fibers when they come into contact with other surfaces, but the loss of fibers through the air and their transfer to other surfaces is now proven. We also know that fibers will be lost when line drying clothes. Although textile scientists are gaining a better understanding of the relationship between the construction of fibres, yarns and textiles and the loss of microfibers during washing, further research will be needed to understand if the same principles apply to other fabrics. other modes of microfiber release. And we still don’t have a clear understanding of the relative amounts of microfibers released from textiles into the air and water from these sources, or the ultimate fate of these fibers. However, there is a clear consensus that measures to reduce the intrinsic ‘shedding’ of garments will be a step in the right direction and we anticipate that future government legislation will bring about all the necessary changes in the manufacture of textiles, in accordance to proposed legislation in several markets to include microfiber filters in new washing machines.

PLOS: Several other studies in this Collection also look at the effects of plastic pollution on living species. One is “Kapp KJ, Miller RZ (2020) Electric clothes dryers: an underestimated source of microfiber pollution. PLoS ONE 15(10): e0239165. https://doi.org/10.1371/journal.pone.0239165“Has seeing these other research studies in the collection helped inspire thoughts about future work you might do or other advances your research community will make?”

NL: Kapp and Miller’s paper was a breakthrough in being the first to recognize and begin to quantify the contribution of vented clothes dryers to air (and subsequent land) pollution. Their methods involving the use of snow to collect the deposited microfibers were fantastic. As their study only involved two dryers and did not measure the relative amounts of microfibers released during washing and drying, we wanted to build on this study with a larger program covering different markets, the impact of cleaning products tissues and the evaluation of some potential solutions. The amount of tumble dryer focused literature is still very limited, so we would like to continue our research in this area with a focus on condenser tumble dryers which are already very common outside of North America and , when integrated with heat pump technology, are much more energy efficient. resulting in lower operating costs and a reduced carbon footprint.

Stay tuned for more interviews with the authors of this collection, including Kapp and Miller who contributed Electric clothes dryer: an underestimated source of microfiber pollution

Cover picture: Port of Dover2014 Clean Beach (CC-BY 2.0)

Disclaimer: Opinions expressed by contributors are solely those of the individual contributors, and not necessarily those of PLOS.

Bryce K. Locke