Vehicle emissions and industrial activities as major sources of methylsiloxanes in urban road dust: a nationwide study in China

Abstract

Methylsiloxanes (MSs) are anthropogenic substances that do not occur naturally, and most studies have focused on their presence in indoor environments. To date, there is limited information regarding their prevalence in road dust across broad geographical scales, with even fewer studies identifying the sources of MSs. This research investigates the levels, regional distributions, and potential origins of MSs in road dust collected from major cities throughout China. The results indicate that these chemicals are prevalent in road dust, with total concentrations of the target MSs ranging from 6.36 to 8618 ng/g dw. Tetradecamethylcycloheptasiloxane was identified as the dominant methylsiloxane. Spatial variations were primarily associated with traffic flow, the value added by the secondary industry, and local population density. Principal component analysis combined with multiple linear regression and positive matrix factorization revealed that vehicle emissions (41.8%–42.3%), industrial activities (38.9%–47.2%), and the use of personal care and consumer products (11.0%–18.8%) were the major contributors to MSs in road dust. The overall source contributions identified by both methods were consistent. These findings highlight the significant role of vehicle emissions and industrial activities and provide valuable insights for developing policies aimed at managing MSs in urban areas.

Graphical abstract

Keywords

Methylsiloxanes / Road dust / Source / Principal component analysis/multiple linear regression / Positive matrix factorization

Highlight

	● Methylsiloxanes (MSs) were ubiquitously detected in road dust across China.
	● Tetradecamethylcycloheptasiloxane (D7) was identified as the most abundant congener.
	● Spatial variations of MSs were linked to traffic, industry, and population density.
	● Vehicle emissions and industrial activities were major sources of MSs in road dust.

References

[1] Brunet C E , Marek R F , Stanier C O , Hornbuckle K C . (2024). Concentrations of volatile methyl siloxanes in new york city reflect emissions from personal care and industrial use. Environmental Science & Technology, 58(20): 8835–8845

[2] Capela DAlves AHomem VSantos L (2016). From the shop to the drain—volatile methylsiloxanes in cosmetics and personal care products. Environment International, 92–93: 92–93

[3] Casotti Rienda I , Alves C A . (2021). Road dust resuspension: a review. Atmospheric Research, 261: 105740

[4] Chen W M , Kang Y J , Lee H K , Lee M , Moon H B . (2022). Nationwide monitoring of cyclic and linear siloxanes in sediment and bivalves from Korean coastal waters: occurrence, geographical distribution, and bioaccumulation potential. Marine Pollution Bulletin, 185: 114201

[5] Chen W M , Oh J S , Lim J E , Moon H B . (2023). Occurrence, time trends, and human exposure of siloxanes and synthetic musk compounds in indoor dust from Korean homes. Ecotoxicology and Environmental Safety, 266: 115538

[6] Cheng J L , Tang Z W , Ma Y , Yin H M , Meng T , Sun J Z . (2021a). Methyl siloxanes in road dust from a large silicone manufacturing site in China: implications of human exposure. Environmental Science and Pollution Research, 28(13): 16054–16064

[7] Cheng Z , Qiu X H , Shi X D , Zhu T . (2021b). Identification of organosiloxanes in ambient fine particulate matters using an untargeted strategy via gas chromatography and time-of-flight mass spectrometry. Environmental Pollution, 271: 116128

[8] Dudzina T , Von Goetz N , Bogdal C , Biesterbos J W H , Hungerbühler K . (2014). Concentrations of cyclic volatile methylsiloxanes in European cosmetics and personal care products: prerequisite for human and environmental exposure assessment. Environment International, 62: 86–94

[9] Feng J L , Zhang F , Zhao J H , Guo W , Sun J H . (2018). An improved quantification method for 12 linear dimethylsiloxanes and 1 cyclic dimethylsiloxane in polydimethylsiloxane using gas chromatography-flame ionization detector: development strategy and accuracy. Journal of Chromatography A, 1578: 112–116

[10] Fromme H , Witte M , Fembacher L , Gruber L , Hagl T , Smolic S , Fiedler D , Sysoltseva M , Schober W . (2019). Siloxane in baking moulds, emission to indoor air and migration to food during baking with an electric oven. Environment International, 126: 145–152

[11] Gkatzelis G I , Coggon M M , McDonald B C , Peischl J , Aikin K C , Gilman J B , Trainer M , Warneke C . (2021). Identifying volatile chemical product tracer compounds in U.S. cities. Environmental Science & Technology, 55(1): 188–199

[12] Horii Y , Kannan K . (2008). Survey of organosilicone compounds, including cyclic and linear siloxanes, in personal-care and household products. Archives of Environmental Contamination and Toxicology, 55(4): 701–710

[13] Horii YKannan K (2020). Main uses and environmental emissions of volatile methylsiloxanes. In: Homem V, Ratola N, eds. Volatile Methylsiloxanes in the Environment. Cham: Springer, 33–70

[14] Jiang J L , Ding X S , Patra S S , Cross J N , Huang C X , Kumar V , Price P , Reidy E K , Tasoglou A , Huber H . et al. (2023). Siloxane emissions and exposures during the use of hair care products in buildings. Environmental Science & Technology, 57(48): 19999–20009

[15] Li L W , Chang R W , Li J P , Zhang H , Du X Y , Li J , Yuan G L . (2024). Assessing the impact of mining on cyclic and linear methylsiloxane distribution in Tibetan soils: source contribution and transport pattern. Science of the Total Environment, 938: 173542

[16] Liu N N , Sun H Y , Xu L , Cai Y Q . (2021). Methylsiloxanes in petroleum refinery facility: their sources, emissions, environ-mental distributions and occupational exposure. Environment International, 152: 106471

[17] Liu N N , Xu L , Cai Y Q . (2018). Methyl siloxanes in barbershops and residence indoor dust and the implication for human exposures. Science of the Total Environment, 618: 1324–1330

[18] Lu J , Wu J , Zhang C , Wang J H , He X . (2024). Occurrence and possible sources of antibiotic resistance genes in seawater of the South China Sea. Frontiers of Environmental Science & Engineering, 18(9): 108

[19] Lu Y , Yuan T , Wang W H , Kannan K . (2011). Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China. Environmental Pollution, 159(12): 3522–3528

[20] Lu Y , Yuan T , Yun S H , Wang W H , Wu Q , Kannan K . (2010). Occurrence of cyclic and linear siloxanes in indoor dust from China, and implications for human exposures. Environmental Science & Technology, 44(16): 6081–6087

[21] Ma C , Wang M L , Li Q , Vakili M , Zhang Y J , Hei S Q , Gao L , Wang W , Liu D C . (2025). Distribution, source apportionment, and assessment of heavy metal pollution in the Yellow River Basin, northwestern China. Frontiers of Environmental Science & Engineering, 19(2): 16

[22] Meng T , Su S , Cheng J L , Zhong F Y , Tang Z W . (2021). Methylsiloxanes in street dust from Hefei, China: distribution, sources, and human exposure. Environmental Research, 201: 111513

[23] Molinier B , Arata C , Katz E F , Lunderberg D M , Liu Y J , Misztal P K , Nazaroff W W , Goldstein A H . (2022). Volatile methyl siloxanes and other organosilicon compounds in residential Air. Environmental Science & Technology, 56(22): 15427–15436

[24] Niu H R , Su X F , Li Q , Zhao J H , Hou M Y , Dong S Y , Yan X , Sun J H , Feng J L . (2023). Dimethylsiloxanes in dust from nine indoor microenvironments of Henan Province: occurrence and human exposure assessment. Science of the Total Environment, 903: 166546

[25] Shi Y L , Xu S H , Xu L , Cai Y Q . (2015). Distribution, elimination, and rearrangement of cyclic volatile methylsiloxanes in oil-contaminated soil of the Shengli oilfield, China. Environmental Science & Technology, 49(19): 11527–11535

[26] Tran T M , Abualnaja K O , Asimakopoulos A G , Covaci A , Gevao B , Johnson-Restrepo B , Kumosani T A , Malarvannan G , Minh T B , Moon H B . et al. (2015). A survey of cyclic and linear siloxanes in indoor dust and their implications for human exposures in twelve countries. Environment International, 78: 39–44

[27] Tran T M , Hoang A Q , Le S T , Minh T B , Kannan K . (2019). A review of contamination status, emission sources, and human exposure to volatile methyl siloxanes (VMSs) in indoor environments. Science of the Total Environment, 691: 584–594

[28] Tran T M , Kannan K . (2015). Occurrence of cyclic and linear siloxanes in indoor air from Albany, New York, USA, and its implications for inhalation exposure. Science of the Total Environment, 511: 138–144

[29] Tran T M , Tu M B , Vu N D . (2018). Cyclic siloxanes in indoor environments from hair salons in Hanoi, Vietnam: emission sources, spatial distribution, and implications for human exposure. Chemosphere, 212: 330–336

[30] Wang R , Moody R P , Koniecki D , Zhu J P . (2009). Low molecular weight cyclic volatile methylsiloxanes in cosmetic products sold in Canada: implication for dermal exposure. Environment International, 35(6): 900–904

[31] Whelan M J , Kim J . (2022). Application of multimedia models for understanding the environmental behavior of volatile methyl-siloxanes: fate, transport, and bioaccumulation. Integrated Environmental Assessment and Management, 18(3): 599–621

[32] Xu L , Shi Y L , Liu N N , Cai Y Q . (2015). Methyl siloxanes in environmental matrices and human plasma/fat from both general industries and residential areas in China. Science of the Total Environment, 505: 454–463

[33] Xu L , Zhi L Q , Cai Y Q . (2017). Methylsiloxanes in children silicone-containing products from China: profiles, leaching, and children exposure. Environment International, 101: 165–172

[34] Yao P , Holzinger R , Materić D , Oyama B S , de Fátima Andrade M , Paul D , Ni H Y , Noto H , Huang R J , Dusek U . (2023). Methylsiloxanes from vehicle emissions detected in aerosol particles. Environmental Science & Technology, 57(38): 14269–14279

[35] Zhu Y H , Tang Z W , He Y , Wang F , Lyu Y . (2023). Occurrence of methylsiloxanes in indoor store dust in China and potential human exposure. Environmental Research, 218: 114969

RIGHTS & PERMISSIONS

Higher Education Press 2026