Urban vegetable contamination - The role of adhering particles and their significance for human exposure

• Published in: The Science of the total environment Vol. 900; p. 165633
• Main Authors: Augustsson, A., Lundgren, M., Qvarforth, A., Engström, E., Paulukat, C., Rodushkin, I., Moreno-Jiménez, E., Beesley, L., Trakal, L., Hough, R.L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.11.2023
• Subjects: Applied Geochemistry; Arsenic; Cadmium; Environmental Science; Foliar contamination; Lead; Miljövetenskap; Particulate matter; Risk assessment; Tillämpad geokemi; Urban farming; Urban produce safety; Urban soil; Foliar contamination; Cadmium; Urban produce safety; Arsenic; Urban soil; Particulate matter; Risk assessment; Lead; Urban farming
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.165633

While urban-grown vegetables could help combat future food insecurity, the elevated levels of toxic metals in urban soils need to be met with measures that minimise transfer to crops. This study firstly examines soil/dust particle inclusion in leafy vegetables and its contribution to vegetable metals (As, Ba, Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn), using vegetable, soil and dust data from an open-field urban farm in southeastern Sweden. Titanium concentrations were used to assess soil/dust adherence. Results showed that vegetables contained 0.05–1.3 wt% of adhering particles (AP) even after washing. With 0.5 % AP, an adult with an average intake of vegetables could ingest approximately 100 mg of particles per day, highlighting leafy vegetables as a major route for soil/dust ingestion. The presence of adhering particles also significantly contributed to the vegetable concentrations of As (9–20 %), Co (17–20 %), Pb (25–29 %), and Cr (33–34 %). Secondly, data from an indoor experiment was used to characterise root metal uptake from 20 urban soils from Sweden, Denmark, Spain, the UK, and the Czech Republic. Combining particle adherence and root uptake data, vegetable metal concentrations were calculated for the 20 urban soils to represent hypothetical field scenarios for these. Subsequently, average daily doses were assessed for vegetable consumers (adults and 3–6 year old children), distinguishing between doses from adhering particles and root uptake. Risks were evaluated from hazard quotients (HQs; average daily doses/tolerable intakes). Lead was found to pose the greatest risk, where particle ingestion often resulted in HQs > 1 across all assessed scenarios. In summary, since washing was shown to remove only a portion of adhering metal-laden soil/dust particles from leafy vegetation, farmers and urban planners need to consider that measures to limit particle deposition are equally important as cultivating in uncontaminated soil. [Display omitted] •Urban vegetables contain adhering particles (APs) even after washing.•The APs significantly contribute to the total human ingestion of particles.•Foliar contamination by particles is crucial for the intake of several metals.•The APs contribute most to the intake of Pb, with ADDs frequently > TDIs.