Monitoring of Metal(loid)s Using Brachiaria decumbens Stapf Leaves along a Highway Located Close to an Urban Region: Health Risks for Tollbooth Workers

Studies on tollbooth workers involving the concentration of metal(loid)s in highway dust are scarce. We aimed to assess the levels of metal(loid)s in soils and washed and unwashed leaves of Brachiaria decumbens on roadsides. Dust deposition and heavy metal content in the leaves are used to estimate the exposure of tollbooth workers to oral, inhalation, and dermal ingestion of metals in highway dust. The concentrations of aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), zinc (Zn), and lead (Pb) in washed and unwashed soil and leaves were analyzed using inductively coupled plasma optical emission spectroscopy. The results showed that soils along highways had a high concentration of heavy metals. Concentrations of Cd, Cu, Cr, Ni, and Pb near the roundabout and tollbooth are higher than the concentrations at the points between them. The highest transfer factor values were determined for aluminum. In the case of the non-carcinogenic effect, the hazard index (HI < 1) of tollbooth workers due to oral exposure to street dust containing metal(loid)s is higher than dermal contact and inhalation. The Incremental Lifetime Cancer Risk showed a high potential carcinogenic risk for As and Cd.