Impacts of Vehicle Emissions and Ambient Atmospheric Deposition in Nigeria on the Pb, Cd, and Ni Content of Fermented Cassava Flour Processed by Sun-Drying

A study of air pollution in Nigeria due to Pb, Cd, and Ni contamination of fermented cassava meant for flour production was carried out by AAS. Fermented cassava samples were purchased from farmers in the study area and one-third of each was oven-dried (OD) while the rest were sun-dried either along roadside (RS-SD) or under ambient atmosphere conditions (AA-SD). Mean concentrations (g/g) for OD samples in year 2008 were: Pb (0.17 +/- 0.04); Cd (0.04 +/- 0.01); and Ni (0.27 +/- 0.05) while RS-SD samples gave Pb (0.24 +/- 0.08), Cd (0.04 +/- 0.01), and Ni (0.48 +/- 0.17). Mean values (g/g) in 2009 for OD, AA-SD, and RS-SD, respectively, were Pb (0.03 +/- 0.01, 0.05 +/- 0.02, 0.15 +/- 0.08), Cd (0.18 +/- 0.01, 0.04 +/- 0.02, 0.05 +/- 0.02), and Ni (0.09 +/- 0.06, 0.21 +/- 0.10, 0.57 +/- 0.12). Mean concentrations in sun-dried samples were greater (p .01), while RS-SD samples were 185% in Pb, 53% in Cd, and 176% in Ni greater (p .01) than AA-SD samples. With an estimated country-wide annual Pb emissions from petrol and diesel ranging from 616,241 to 968,086 kg, and dust, considered the major source of Cd and Ni, and other extraneous factors including metals adsorbed on pavement surfaces, sun-drying of wet foodstuff on the bare surface of roadside pavements could lead to high levels of Pb, Cd, and Ni in such food compared to drying under factory conditions or oven-drying.