Determination Of Heavy Metals In Plastic Housing Of Selected Obsolete Mobile Phones And Television Produced In Some Years Between 1980 And 2000

ABSTRACT

Theconcentrations of lead, nickel, silver, zinc, chromium, copper, vanadium, cobalt, and

cadmium were determined in plastic housing of waste television sets produced in some years of

1980’s, 1990’s and 2000’s, and in plastics of waste mobile phones produced in some years of

1990’s and 2000’s, the samples were collected mainly from mobile phone and television

repairers at railway in Ogbete main market, Enugu in Enugu state, and the famous computer

village inIkeja, Lagos State Nigeria, with the aim of providing information on the trend in

concentration of these metals within the years. The concentrations of these nineelements were

determined by flame atomic absorption spectrometry after acid digestion using a 1:1 mixture of

sulphuric and nitric acid. The mean concentration of these metals (mg/kg) in the television set for

the 1980’s, 1990’s and 2000’s respectively are (12.76±17.61, ND, 1.33±2.30) for lead;

(1.84±1.33, 1.48±1.26, 2.79±2.47) for nickel; (1.53±2.35, 16.20±29.66, 40.42±20.49) for silver;

(82.24±50.59, 159.69±55.87, 113.29±69.175) for zinc; (7.12±10.50, 4.23±1.07, 5.26±4.73) for

chromium; (3.26±1.09, 2.76±1.15, 2.39±1.05) for copper; (4.84±10.83, 24.05±7.56,

26.67±11.13) for vanadium; (9.30±5.27, 8.40±3.00, 12.63±12.99) for cobalt; (2.60±1.25,

4.05±1.81, 4.28±1.11) for cadmium (ND - Not Detected). The mean concentration of these

metals (mg/kg) in the mobile phones are (50.83±65.85, 5.71±3.55) for lead; (23.80±27.89,

1.95±1.28) for nickel; (48.04±89.00, 7.82±4.61) for silver; (325.11±261.50, 105.59±26.72) for

zinc; (5.47±3.97, 4.38±3.93) for chromium; (643.92±880.48, 47.51±97.06) for copper;

(20.94±5.59, 34.50±25.61) for vanadium; (4.92±1.55, 13.21±8.16) for cobalt; (8.14±7.06,

17.60±19.14) for cadmium.The total threshold limit concentration of these metals are; lead-

1000, nickel- 2000, silver 500, zinc- 5000, chromium- 2500, copper-2500, vanadium-2400,

cobalt-8000, cadmium-100 (mg/kg) (sourced from California Code of Regulations). Although

the mean concentration values of Zn, Cu and Ag in both the mobile phones and television

samples were relatively high compared to the total threshold limit concentration (TTLC), all the

metal concentration values were below the threshold limit except for Ag. Two results exceeded

the TTLC threshold for Ag (500 mg/kg) within phone samples (1990). These results suggest that

there may not be any immediate danger from waste television and mobile phone plastic housing

investigated.