Professor Joanne Kwan, senior research manager and sustainable land reuse lead at CIRIA, discusses the issue of microplastics in the built environment and their effects on health
Plastics were invented by Leo Baekeland, a Belgian chemist who emigrated to the USA in 1907. A century later, plastic materials dominate every sphere of human activity due to their numerous qualities, such as durability, sturdiness and affordability. In the 21st century, it is hard to imagine everyday life without plastics.
However, the negative effects of plastics on the environment and human health have begun to emerge in recent years. Microplastics – small plastic particles ranging from 100nm to 5mm generated from the breakdown of larger plastic pieces – are increasingly recognised as significant emerging contaminants in soil and water (Prasittisopin et al., 2023).
What are microplastics?
Microplastics can be divided into two groups:
- Primary – particles intentionally produced at microscopic sizes. These include plastic pellets (or nurdles) used in industrial manufacturing and plastic fibres used in synthetic textiles, such as nylon (UK CEH, n.d.).
- Secondary – particles generated from the degradation of larger plastic materials because of mechanical strain, hydrolysis, oxidation and weathering effects from UV light, heat and microorganisms. Secondary microplastics, such as those generated from construction activities, are the main contributors to the total amount of microplastics found in the environment (An et al, 2020 and Prasittisopin et al, 2023).
Effects on human health and the environment
Recent research has shown that microplastics increase ecotoxicology risks in aquatic environments. They can adsorb toxic materials such as polycyclic aromatic hydrocarbon, heavy metals, and pathogens, which causes deleterious effects on aquatic species, resulting in oxidative stress and decreased nutrient uptake (Anik et al, 2021).
A recent report highlighted a potential link between microplastics in blood vessels and cardiovascular disease. Some microplastics are endocrine disrupters that can affect human health. Workers exposed to high levels of plastic dust suffer chronic inflammation of the airway and, in some cases, interstitial lung disease and tissue scarring (Saha and Saha, 2024, Lu et al, 2022, Amato-Lourenço et al, 2020).
World oceans are the greatest carbon sink and oxygen producers on the planet, playing a very crucial role in regulating the climate. Microplastics hinder the ocean’s climate mitigation potential in many different ways. If present in the water column, they can disrupt the balance of the natural carbon sequestration by affecting the growth and photosynthesis efficiency of phytoplankton and zooplankton (Parvez et al., 2024).
The presence of microplastics in soils harms their structure and physical properties, including soil aggregate, water stability, bulk density, pneumatic conductivity, and rhizosphere function. Microplastics have been shown to increase the emission of carbon dioxide (CO2), nitrous oxide (N2O) and other greenhouse gases from the soil by changing physical and microbiological properties (Parvez et al., 2024).
How do microplastics enter the human body?
Humans can inhale microplastics from the air, directly ingest them from water, and absorb them through the skin (Fig. 1). Ingestion of microplastics by beach-dwelling and marine organisms like crustaceans and molluscs also means microplastics are passed up the food chain to birds, fish and mammals who feed on those organisms.
Microplastics have been found in various human organs, including in the placenta of babies (UN Environmental Programme, 2023).
The relationship between microplastics and construction
There are many reasons that construction professionals need to better manage microplastics in their projects, including:
Construction is a big plastic consumer and substantial microplastic generator
There are still a lot of uncertainties in how much microplastics construction projects generate. However, the industry is the second largest user of plastic, consuming around 20% of all plastic (Considerate Construction Scheme, n.d.). Plastics are a vital component in pipes, doors and windows, flooring, fibre reinforcement in concrete, paint, plastic beads and insulation, microbeads, sheet insulation and plastic pipes, and claddings often contain plastics (as in the image below). The more plastics are used, the more microplastics are released, and the contribution of microplastics from construction is significant.
The impact of microplastics is serious
It is now generally agreed that microplastics can induce immunotoxicity, cytotoxicity and reproductive consequences in humans. A study in the USA indicated that while there are uncertainties due to the presence of microplastics in numerous building materials, the impacts of microplastics generated in the construction sector are significant (Prasittisopin, 2023).
Increasing public perception
There has been enormous media attention on microplastics in recent years. The construction industry, like many other industries, is under increasing pressure to demonstrate they are managing microplastics in their projects.
Growing attention from regulators and policy makers
In 2023, the European Commission (EC) adopted “a REACH restriction on microplastics intentionally added to products and a proposal for a Regulation on preventing plastic pellet losses to the environment” (EC, 2023). These actions will directly contribute to reaching the 30% reduction target for microplastic releases set by the EC (2021).
In England, the Environment Agency (EA) does not currently routinely monitor for microplastics in the environment but responds to plastic pollution based on incident reporting (EA, 2022).
Microplastic pollution is also a rising global issue with significant policy implications, especially in the context of the UN Sustainable Development Goals (SDGs) (Walker, 2021). The policy implications to address microplastics within the SDGs are diverse and encompass various crucial domains, such as environmental sustainability, responsible consumption and production, public health, partnerships for global action, and clean water and sanitation.
Industry knowledge – how can it ‘do better’?
Guidance on microplastics is very scattered. One of the more comprehensive guidance was developed by the Interstate Technology Regulatory Council in the USA (ITRC, 2023), and there are research findings from academic institutions such as the University of Portsmouth and the University of Manchester. However, more research and an improved understanding of microplastics regarding their effects on the environment and human health is needed, and construction projects need to develop materials that generate less microplastics.
Some construction companies have already taken the lead to understand microplastics. A recent study carried out by National Highways in 2021 on heavy traffic motorways reveals surface water runoff is a significant source of microplastics, much of which comes from construction traffic, gullies, asphalt, thermoplastic road markings, etc.
However, the industry cannot afford to wait for the result of research before taking action. People in the UK and Ireland already breathe in more microplastic dust than in any other country (Kings College, 2019). There is an urgent need for construction projects, particularly those in highly populated cities with multiple regeneration schemes like London, to reduce microplastic exposure to site workers and the local community.
A recent article has made several recommendations on how building surveyors, designers, site managers, etc, could do better (Smethurst, 2023). The main emphasis is to reduce the excessive use of plastics and avoid plastic products or look for alternatives such as natural, non-hybrid or easily reusable materials.
However, more information is needed on:
- How much microplastic is generated from construction projects; this includes developing good practices in sampling and analysis of microplastics in air, soil and water
- Understanding which construction activities are likely to generate microplastics and how they can be controlled
- Raising awareness to construction professionals, including site workers; they need to recognise microplastics as a critical issue and know how to manage them in their projects.
CIRIA, a leading construction industry guidance provider, has recently launched a new project on Microplastics in construction projects – current knowledge and good practice guidance (P3283). It will produce the first UK good practice guidance that will improve the industry’s understanding of the source, fate, transport, impact, and mitigation approach for microplastics in construction projects. It will also help construction professionals to reduce the generation and spread of microplastics on construction sites.
The project is supported by Atkins Réalis, Kier Transport, and Transport for London.
To find out more and get involved in this exciting and important research, go to: https://www.ciria.org/Research/Projects_underway2/Microplastics%20in%20construction%20projects.aspx or contact Joanne Kwan at CIRIA (joanne.kwan@ciria.org)
References
LAMING, D (2024) Going ‘plastic-free’ in the construction industry, Tradesman Saver, Sutton, Surrey
SWEE-LI YEE, M, HII, L-W, LOOI, C K, LIM, W-M, WON, S-F, KOK, Y-Y, TAN, B-K, WONG, C-Y and LEONG C-O (2021) “Impact of microplastics and nanoplastics on human health”, Nanomaterials (Basel)2021 Feb 16;11(2):496, National Library of Medicine, Maryland, USA
https://doi.org/10.3390/nano11020496
UN ENVIRONMENT PROGRAMME (2023) Microplastics: The long legacy left behind by plastic pollution, United Nations, Nairobi, Kenya
https://www.unep.org/news-and-stories/story/microplastics-long-legacy-left-behind-plastic-pollution
