Influence of Urban Informal Settlements on Trace Element Accumulation in Road Dust and Their Possible Health Implications in Ekurhuleni Metropolitan Municipality, South Africa

Abstract

The study was aimed at assessing the influence of urban informal settlement on trace element accumulation in road dust from the Ekurhuleni Metropolitan Municipality, South Africa, and their possible health implications. The concentration of major and trace elements was determined using the wavelength dispersive XRF method. The major elements in descending order were SiO2 (72.76%), Al2O3 (6.90%), Fe2O3 (3.88%), CaO (2.71%), K2O (1.56%), Na2O (0.99%), MgO (0.94%), MnO (0.57%), TiO2 (0.40%), and P2O5 (0.16%), with SiO2 and P2O5 at above-average shale values. The average mean concentrations of 17 trace elements in decreasing order were Cr (637.4), Ba (625.6), Zn (231.8), Zr (190.2), Sr (120.2), V (69), Rb (66), Cu (61), Ni (49), Pb (30.8), Co (17.4), Y (14.4), Nb (8.6), As (7.2), Sc (5.8), Th (4.58), and U (2.9) mg/kg. Trace elements such as Cr, Cu, Zn, Zr, Ba, and Pb surpassed their average shale values, and only Cr surpassed the South African soil screening values. The assessment of pollution through the geo-accumulation index (Igeo) revealed that road dust was moderately to heavily contaminated by Cr, whereas all other trace elements were categorized as being uncontaminated to moderately contaminated. The contamination factor (CF) exhibited road dust to be very highly contaminated by Cr, moderately contaminated by Zn, Pb, Cu, Zr, and Ba, and lowly contaminated by Co, U, Nb, Ni, As, Y, V, Rb, Sc, Sr, and Th. The pollution load index (PLI) also affirmed that the road dust in this study was very highly polluted by trace elements. Moreover, the results of the enrichment factor (EF) categorized Cr as having a significant degree of enrichment. Zn was elucidated as being minimally enriched, whereas all other trace elements were of natural origin. The results of the non-carcinogenic risk assessment revealed a possibility of non-carcinogenic risks to both children and adults. For the carcinogenic risk, the total CR values in children and adults were above the acceptable limit, signifying a likelihood of carcinogenic risk to the local inhabitants. From the findings of this study, it can be concluded that the levels of trace elements in the road dust of this informal settlement had the possibility to contribute to both non-carcinogenic and carcinogenic risks, and that children were at a higher risk than the adult population.

Herbicides in Water Sources: Communicating Potential Risks to the Population of Mangaung Metropolitan Municipality, South Africa

“…Therefore, the health risks of pesticides were focused on oral ingestion. This is because ingestion remains a major risk among the various routes of exposure [ 36 , 37 , 39 ]. The risks of pesticides with unknown cancer slope factors were not assessed.…”

“…The average daily dose ( ADD ) of pesticides ingested by adults and children is calculated using Equation (3). Because of their behavioural and physiological differences, it is calculated separately [ 36 , 37 , 39 ]: …”

“…The non-carcinogenic risk is then calculated by dividing the average daily doses in Equation (4) by a corresponding reference dose ( RfD ) in Table 6 . Equation (5) is then used to calculate the hazard index ( HI ) [ 36 , 39 ]: where if the hazard quotient or index is less than one, it indicates a very low risk; between one and four, it indicates a possible risk; and when greater than four, it indicates a high risk [ 36 , 39 ]. The ADD values in Equation (3) are also used to compute the cancer risk ( CR ) of each examined contaminant.…”

“…The permitted risk ranges are <10 −6 (very low risk), 10 −6 –10 −5 (low risk), 10 −5 –10 −4 (medium risk), 10 −4 –10 −3 (high risk), and >10 −3 (very high risk) [ 36 , 39 ].…”

Editorial for the Special Issue “Potentially Toxic Elements Pollution in Urban and Suburban Environments”

“…More attention was placed on an environmental compartment considered a lesserknown air pollutant such as dust, both in a road and a household. In fact, Mugudamani et al [18] determined the influence of urban informal settlements on trace element accumulation in road dust from Ekurhuleni Metropolitan Municipality, South Africa, and their health implications. The outcomes of this study revealed that informal settlement activities have considerable influences on the accumulation of trace elements in road dust during the winter season.…”