Levels and occupational health risk assessment of trace metals in soils from automobile repair workshop village and environs in Uyo metropolis, Nigeria

Abstract

The levels of trace metals (Pb, Cu, Ni and Cd) were determined in soils from a major automobile repair workshop located in Uyo, Akwa Ibom State, Nigeria. This was carried out to evaluate the potential occupational risk to operators working in and around the site. The mean of trace metal levels were: lead (14.52 mg/kg); copper (0.50 mg/kg); nickel (0.17 mg/kg) and cadmium (0.67 mg/kg). These values were within the acceptable levels for unpolluted soils according to the Dutch standard. The trace metal levels were subjected to risk assessment model to estimate toxic risks due to occupational exposures by incidental oral ingestion of soil particles. The results obtained revealed higher risk quotients for exposed workers at the main automobile workshop area than those occupants farther away. Amongst the metals studied, lead was predicted to pose higher health risk although the hazard quotients for all trace metals were less than one. This indicates that there is little or no significant occupational health risk associated with the presence of these levels of trace metals in the soils. The physicochemical measurements gave the following mean values: pH 6.01; total organic carbon 4.05 %, while the mean particle size distributions were: sand 95.15%; clay 0.7% and silt 4.25%. The pH value of the soil under study showed slight acidity which implies that the trace metals are less likely to be solubilized. The elements are also capable of binding to the organics present in the soil; while the high sand content of the soil implies that the trace elements can be easily leached, thus being more bioavailable for uptake by plants.

Key words: Trace metals, occupational risk assessment, automobile shop, soils, physicochemical parameters.