TY - JOUR
T1 - Estimation of daily intake of potentially toxic elements from urban street dust and the role of oral bioaccessibility testing
AU - Okorie, Ikechukwu
AU - Entwistle, Jane
AU - Dean, John
PY - 2012
Y1 - 2012
N2 - The pseudo-total and oral bioaccessible concentration of six potentially toxic elements (PTEs) in urban street dust was investigated. Typical pseudo-total concentrations across the sampling sites ranged from 4.4 to 8.6 mg kg−1 for As, 0.2–3.6 mg kg−1 for Cd, 25–217 mg kg−1 for Cu, 14–46 mg kg−1 for Ni, 70–4261 mg kg−1 for Pb, and, 111–652 mg kg−1 for Zn. This data compared favourably with other urban street dust samples collected and analysed in a variety of cities globally; the exception was the high level of Pb determined in a specific sample in this study. The oral bioaccessibility of PTEs in street dust is also assessed using in vitro gastrointestinal extraction (Unified Bioaccessibility Method, UBM). Based on a worst case scenario the oral bioaccessibility data estimated that Cd and Zn had the highest % bioaccessible fractions (median >45%) while the other PTEs i.e. As, Cu, Ni and Pb had lower % bioaccessible fractions (median <35%). The pseudo-total and bioaccessible concentrations of PTEs in the samples has been compared to estimated tolerable daily intake values based on unintentional soil/dust consumption. Cadmium, Cu and Ni are well within the oral tolerable daily intake rates. With respect to As and Pb, only the latter exceeds the TDIoral if we model ingestion rate based on atmospheric ‘dustiness’ rather than the US EPA (2008) unintentional soil/dust consumption rate of 100 mg d−1. We consider it unlikely that even a child with pica tendencies would ingest as much as 100 mg soil/dust during a daily visit to the city centre, and in particular to the sites with elevated Pb concentrations observed in this study.
AB - The pseudo-total and oral bioaccessible concentration of six potentially toxic elements (PTEs) in urban street dust was investigated. Typical pseudo-total concentrations across the sampling sites ranged from 4.4 to 8.6 mg kg−1 for As, 0.2–3.6 mg kg−1 for Cd, 25–217 mg kg−1 for Cu, 14–46 mg kg−1 for Ni, 70–4261 mg kg−1 for Pb, and, 111–652 mg kg−1 for Zn. This data compared favourably with other urban street dust samples collected and analysed in a variety of cities globally; the exception was the high level of Pb determined in a specific sample in this study. The oral bioaccessibility of PTEs in street dust is also assessed using in vitro gastrointestinal extraction (Unified Bioaccessibility Method, UBM). Based on a worst case scenario the oral bioaccessibility data estimated that Cd and Zn had the highest % bioaccessible fractions (median >45%) while the other PTEs i.e. As, Cu, Ni and Pb had lower % bioaccessible fractions (median <35%). The pseudo-total and bioaccessible concentrations of PTEs in the samples has been compared to estimated tolerable daily intake values based on unintentional soil/dust consumption. Cadmium, Cu and Ni are well within the oral tolerable daily intake rates. With respect to As and Pb, only the latter exceeds the TDIoral if we model ingestion rate based on atmospheric ‘dustiness’ rather than the US EPA (2008) unintentional soil/dust consumption rate of 100 mg d−1. We consider it unlikely that even a child with pica tendencies would ingest as much as 100 mg soil/dust during a daily visit to the city centre, and in particular to the sites with elevated Pb concentrations observed in this study.
KW - Street dust
KW - potentially toxic elements
KW - daily intake
KW - oral bioaccessibility
KW - in vitro gastrointestinal extraction
U2 - 10.1016/j.chemosphere.2011.09.047
DO - 10.1016/j.chemosphere.2011.09.047
M3 - Article
VL - 86
SP - 460
EP - 467
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
IS - 5
ER -