Risk Assessment and Implication of Human Exposure

Overview

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Key numbers

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values are given in Table 1. The Igeo was computed from the following equation (52)
Mean recoveries for the studied elements (C (element, measured)/C (element, certified) × 100) in
the CRM were between 73.2% and 102.9% (Supplementary information: Table S1). The precision of
was less than 2.5%. The concentration of metals in laboratory blanks, filter blanks and reagent blanks
values are given in Table 1. The Igeo was computed from the following equation (52)
Table 1. Value, classes and qualitative description of geo-accumulation index (Igeo ) *.
McLennan (57). Using average crust values provides a meaningful comparison to many other studies
Table 2. Values of exposure factors for heavy metals doses for children and adults.
in Figure 2. The mean concentrations of heavy metal in descending order were Fe > Mn > Zn > Pb >
Cu > V > Cr > Ni > As > Co. and Cd. The mean concentrations were 12,449.45, 550.61, 487.52, 140.73,
7.46, 80.92, 11.66, 51.29, 21.55, 65.43 and 139.11 mg/kg for Fe, Mn, Zn, Pb, Cd, V, Co, Ni, As, Cr and
except for Fe and Mn. Their mean values were 6.02, 9.25, 18.65, 2.32, 2.53, 2.33, 9.58, 1.59 and 6.89 fold
Co. and Cd in soil are 100, 100, 1500, 300, 30, and 3 mg/kg, respectively (82). In the present study, only
are shown in Table 3. The concentrations of all heavy metals (except Fe in all sites and Mn in RA and
the world is shown in Table 4. In general, the concentrations of heavy metals in Jeddah road dust were
The Igeo values for heavy metals in road dust from different functional areas are presented in Table 5.
Mn, Co and Fe, <1 for Cu and >1 for Cd, As, Pb and Zn (Table 5). According to the criteria of contamination
of urban road dusts based on Igeo (Table 1), urban road dusts of Jeddah was uncontaminated by Ni, Cr, V,
Table 3. Concentrations (mg/kg) of heavy metals in road dusts of different functional areas.
Table 4. Heavy metals concentrations (mg/kg) in urban road dusts of different cities around the world.
Table 5. The enrichment factor (EF) and Igeo of heavy metals in road dusts of different functional areas.
The EF for each heavy metal in road dusts from different functional areas are shown in Table 5.
As and Cu in MCRA, PA and TA were more than 10. Generally, the mean EF values in the urban road
Co. The mean EF values of Mn, V, Co, Ni and Cr were between 2 and 10, indicating that they were
children and adults (Tables 6 and 7). Based on the calculated HQ values for the ingestion (HQing ) and
Table 6. Hazard quotient and hazard index of each heavy metal for children population living in different functional areas.
Table 7. Hazard quotient and hazard index of each heavy metal for adults population living in different functional areas.
When the mean HQs of the five urban areas was calculated (Table 8), the average hazard quotient
(the total risk of non-cacinogenic exposure) were 94.86%, 1.52% and 3.62% for children and 56.13%,
3.01% and 40.86% for adults, respectively. This indicates that ingestion was the main pathway exposure
metals in road dusts from different functional areas are presented in Tables 8 and 9. All CRA values
must be considered. In Saudi Arabia, drinking water, especially water wells (108), vegetables (109),
Table 8. Hazard quotient, hazard index and carcinogenic risk of average concentrations of each heavy metals for both children and adults population living in urban
Table 9. Carcinogenic risk (CRA) of each heavy metal for children and adults population living in
Table S1: Certified and measured values and recovery (C(element measured)/ C(element certified) × 100,%) of
1. Taylor, S.R. Abundance of Chemical Elements in the Continental Crust: A New Table. Geochim. Cosmochim. Acta
1. Balkhair, K.; Ashraf, M. Field accumulation risks of heavy metals in soil and vegetable crop irrigated with
1. Ali, M.; Al-Qahtani, K. Assessment of some heavy metals in vegetables, cereals and fruits in Saudi Arabian

Methods (brief)

Road dusts were collected from five different functional areas (traffic areas (TA), parking areas (PA),
Road dusts samples were collected from five different functional areas in Jeddah and one rural
the city of Jeddah. Road dust samples were collected on the driest month of the year (September 2016).
Samples at each sampling location (approximately 200 g each) were collected by gentle sweeping
brush and dustpan, thus ensuring that the samples were collected from the surface soil. The collected
samples were stored in labeled sealed polypropylene bags and transported to the lab.
Geo-Accumulation samples
the samples, large plant/animal/biological parts, as well as, irrelevant gravel-sized materials, were
the metals in road dust samples. The constant 1.5 is used to minimize the effect of possible variations
2.4. Sample Digestion and Analysis
To measure heavy metal concentration, accurately weighed road dust samples (1 g) were digested
bottles until analysis. Inductively Coupled Plasma Optical Emission Spectrometry ICP-OES-5100 was
and As. The quality of data was ensured using standard material between samples. For quality
the metals in road dust samples. The constant 1.5 is used to minimize the effect of possible variations
The average concentrations of heavy metals in urban road dusts collected from Jeddah are shown
metals in outdoor dust samples in a coal mining area. Environ. Geochem. Health 2013, 35, 347–356. (CrossRef)
1. Maas, S.; Scheifler, R.; Benslama, M.; Crini, N.; Lucot, E.; Brahmia, Z.; Benyacoub, S.; Giraudoux, P. Spatial
1. Lappalainen, R.; Knuuttila, M. Atomic absorption spectrometric evidence of relationships between some

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised