Clean Water and Sanitation (SDG 6), Climate Action (SDG 13)
Physicochemical characterisation and potential health effects of non-exhaust particle emissions David O’Loughlin* 1,2 , Liza Emirali 1 , Molly Haugen 2 , Anne Willis 1 , Adam Boies #2 , Marion MacFarlane #1 1 MRC Toxicology Unit, University of Cambridge. 2 Department of Engineering, University of Cambridge,#Denotes joint senior author Until now, research into the health effects of particulate emissions from vehicles has mainly focused on exhaust (tailpipe) emissions. However, non-exhaust particulate emissions due to brake, tyre, and road wear are produced by electric and combustion-engine vehicles and contribute significantly to airborne particles from road traffic. Brake wear is the most prevalent constituent of roadside PM, accounting for around 16-55% by mass, while tyre wear makes up around 5-30%. Data submitted by the UK Government to the United Nations Convention on Long-range Transboundary Air Pollution forecasts that non-exhaust emissions are expected to rise to 9 kilotonnes by 2030, while exhaust emissions continue to fall. Previous work has shown that both brake and tyre particles have the ability to induce (pro)inflammatory responses in lung cells both in vitro and in vivo. Identifying tyre rubber particles in mixed PM samples is a complex challenge due to the chemically complex and often proprietary composition, designed to maximise performance, reliability or prolong useful life. Tyres are comprised primarily of rubbers including natural rubber, polyisoprene rubber, butadiene rubber, and styrene-butadiene rubber, vulcanisation agents such as ZnO, as well as trace heavy metals - all of which can leach into the environment through aerosolization and water runoff. This project has combined analytical chemistry methods with in vitro toxicology to gain a simultaneous understanding of the size and composition of brake and tyre particles generated on road and in the lab, and their potential human health effects. While zinc has previously been used as a single element tyre tracer, we have determined the most relevant and up to date elemental tyre fingerprint yet including concentrations of 19 elements analysed in 76 tyres, which can be used to quantify human exposure to these particles by X-ray fluorescence (XRF) detectors, which are already deployed at Defra air quality monitoring stations, whereas hydrocarbon tracers require large tandem GC/MS instruments. The potential health effects of these particles continue to be assessed on human bronchial epithelial cells in vitro. Size fractionated samples of brake and tyre wear generated in the lab are used to assess the (pro)inflammatory, cytotoxic, and mitochondrial effects of these particles. The experiments have bene designed under the framework of the IACR Characteristics of Carcinogenicity, to provide structure for the experimental approach and to allow for comparison and contextualisation of results. Preliminary toxicology data show that brake and tyre particles have the ability to reduce mitochondrial function without inducing cell death pathways, with a greater effect than diesel particles at the same dose. Experiments to qualify and quantify cytokine release in response to these particles are in progress and will be completed before the end of the year.
P17
© The Author(s), 2023
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