Toxicological Effects of Electronic Waste (E-waste) on Microbial Flora and Radionuclides
Abstract
This study was conducted to investigate the microbial, elemental levels and radionuclei concentration of three e-waste dumpsites with a view to establish the contamination status of these sites. E-waste soil samples were collected from Oluku and Osasogie in Benin, Edo state Nigeria while the third E-waste soil sample was obtained from Alaba, Lagos state Nigeria.The microbial analysis was done based on standard procedure. The mean bacterial counts on nutrient agar (NA) ranges between 9.00±2.646 cfu/g and 5.33±1.202 cfu/g, the former was for Oluku while the latter was for Osasogie. The highest fungal count was recorded in the control site (10.67±1.764 sfu/g). The isolated bacterial and fungal species included, Bacillus sp., Clostridium sp., Pseudomonas sp., Yersinia sp., Serratia marcescens, Klebsiella sp., Providencia sp, Aspergillus sp., Geotrichum sp., Rhizopus sp., and Penicillium sp. respectively, these microorganisms have been reported to possess the ability to biodegrade heavy metals. The physicochemical properties across the e-waste sites showed the available pH of the soil samples range from 6.83 - 8.45. Alaba soil sample recorded the highest amount of all the heavy metals analyzed, cadmium (Cd) was the only heavy metal that was not detected (ND) and it was not detected only in the control soil sample. The activity concentrations of natural radionuclides (40K, 226Ra, 323Th). The highest mean values obtained for 226Ra and 323Th was in Alaba with (79.630±4.557 Bq/kg, 30.177±1.83 Bq/kg) respectively. The control was below detection limit (BDL) for both Ra and Th. The world average values of 412 Bq/kg, 35 Bq/kg and 30 Bq/kg for 40K,226Ra, and 323Th, respectively. However, 226Ra was higher than the accepted limit while 232Th was at the recommended limit for Alaba e-waste site. Therefore, ewaste poses a radiological risk to the people living/working at Alaba e-waste site, but does not pose any immediate threat at the other two e-waste sites studied.
Keywords: E-waste, heavy metal, microorganisms, dump sites, radionuclides