Abstract

The risk assessment of coatings on mobile phone recharge cards on end users has been investigated using mobile phone recharge cards of three major brands (designated as A, B and C) with dominations of N200, N400 and N500 purchased from retail shops in Zaria, Nigeria. To appraise the health risk associated with heavy metal contamination of food by metals from the coatings, Daily Intake of Metals (DIM) and Health Risk Index (HRI) were calculated. The heavy metals was analysed using AAS. Mean concentration of metal ranged between; 12926 to 130, 554 to 294, 13175 to 7025.5, 23691 to 561, 700 to 222.5, 15230 to 5554, 2745.8 to 1429, and 75525 to 11397 µgg^-1 for Mn, Cu, Cr, Zn, Cd, Ni, Pb and Fe respectively. Generally, high concentration of metals was found in Sample C with the exception of Cu. Also, the distribution concentration of the metals were found to be Fe > Cr > Ni > Pb > Zn > Cd > Cu > Mn, followed by Fe > Pb > Ni > Cr > Zn > Cu > Mn > Cd and Fe > Zn > Ni > Cr > Mn > Pb > Cu > Cd for Samples A, B and C respectively in that order of decreasing magnitude. Analysis of difference of means using t-test (p < 0.05) showed significant difference between samples for Pb, Cu and Cr among the heavy metals determined. The trend of DIMs for heavy metals in the coatings were in the order of Cd > Al > Zn > Fe > Ni > Cr > Mn > Pb > Cu, with intake from Sample B being greater than Samples C and A for Pb, Cu, Cr, Cd and Ni. Also, the HRI of metals indicated that Pb, Cd and Ni (especially Samples B and C) through adhering ‘silver’ coatings on mobile recharge cards on nails or under the finger contaminating food were higher than 1, which indicates that users experience relatively high health risk.

Key words: Heavy metals, recharge cards coating, health risk, AAS, Nigeria.