Risk assessment of human exposure to potentially toxic metals in indoor dust from some small and medium scale enterprise workplace environments in southern Nigeria

This study concerns an assessment of indoor dust from printing press, car spray painting and metal design workshops, with the aim of evaluating the occupational risk arising from exposure to metals present in the dust. The levels of Cd, Pb, Cr, Ni, Cu, Co, Mn, Zn and Fe in the dust samples were quantified by means of atomic absorption spectrometry. The concentrations of metals (mg kg⁻¹) in the indoor dust from these workplace environments varied from <0.003–208 for Cd, 26.5–1530 for Pb, 7.80–346 for Cr, 10.5–490 for Ni, 32.0–1915 for Cu, 3.50–232 for Co, 169–20,300 for Zn, 87.5–7260 for Mn and 8900–661,000 for Fe. The hazard index values were above one for different age groups except for the exposure of teenagers and adults to metals in dusts in the printing press studios and car spray painting workshops. The carcinogenic risk for all age groups relating to human contact with metals (Cd, Pb, Cr and Ni) in dust from these workplace environments via three exposure pathways: oral ingestion, inhalation and dermal contact, were above the safe level of 1.0 × 10⁻⁶ but not up to the level (1.0 × 10⁻⁴) that requires remedial action.