Mobility pattern, risk assessment of heavy metals in soil-dust and hazards of consuming vegetables at auto-body workshops

Abstract

Heavy metal movement pattern, hazards of consuming vegetables and risk assessment of soil-dust at auto-body workshops were studied. Soil-dusts collected from eight different auto-body workshops (A–H), at different depths and distances from workshops in Eastern Nigeria, were pulverized, sieved to obtain finest dust, digested by standard method. Vegetables were ashed, digested using standard methods. Filtrates were assayed for cadmium, chromium, lead, nickel, manganese and copper using atomic absorption spectrophotometry (AAS 205). Results of soil-dust of workshop F has highest Cd (3.93 ± 0.01 mg kg⁻¹). Cr and Pb in workshop F and B were 3.53 ± 0.02 mg kg⁻¹ and 5.19 ± 0.05 mg kg⁻¹. Copper in workshop D (7.31 ± 0.01 mg kg⁻¹) were higher than other metals in all workshops, metals from graduated distances and depths reduced. Highest HQ (adult, children) in workshop A ranged 7.575E−7–1.006E−2, 8.385E−14–2.716E−2 (ingestion); 3.714 E−10–4.933E−6, 1.646E−10–2.530E−6 (inhalation); 7.408E−17 –9.842E−13, 4.244E−18–6.525E−14 (dermal contact). ILCR in workshop A ranged 2.396 E−9–9.745E−8 (ingestion); 1.175E−12–4.778E−11 (inhalation): 2.343E−19–9.530E−18 (dermal contact) for adult, that of children ranged from 5.590E−9–2.27E−7, 5.207E−13–2.118E−11, 1.343 E−20–5.460 E−19 (same routes). Hazard quotient and cancer risk via all routes ranged 10^–18 –10^–2 and 10^–20–10^–7 below EPA’s 1 and 1 × 10^–6–1 × 10^–4 standard. Vegetable metals were minimal than soil-dust. True intake (Cd, Cr, Pb, Mn, Ni, Cu) ranged 14–718 (mg kg⁻¹). Exposure via soil-dust/vegetables can add to human and environmental burden of heavy metals.