Radiological safety assessment and determination of heavy metals in soil samples from some waste dumpsites in Lagos and Ogun state, south-western, Nigeria

Assessment of naturally occurring radionuclides and heavy metals in 5 major dumpsites around Lagos and Ogun State, Nigeria, was carried-out to determine the natural radionuclide and heavy metals in the dumpsites and to evaluate the hazards these may have on the public. Radionuclide concentrations were determined using gamma-ray spectrometry with NaI (Tl) detector. The mean activity concentrations of 226Ra, 232Th and 40K in the soil samples were 23.1 ± 2.5, 35.1 ± 2.1 and 318.9 ± 27.4 Bq kg−1, respectively in Ojota, 32.1 ± 6.1, 44.2 ± 16.0 and 377.4 ± 9.0 Bq kg−1 in Ojo, 18.2 ± 4.8, 28.4 ± 3.1 and 340.9 ± 12.1 in Igando, 26.3 ± 9.0, 38.1 ± 1.1 and 531.1 ± 23.0 in Agbara and 15.3 ± 3.6, 22.3 ± 1.7 and 840.9 ± 42.0 in Ogijo, respectively. The results of 226Ra and 232Th are lower than the world average but higher for 40K (UNSCEAR, 2000). The analysis of the heavy metal concentrations indicated that there is presence of Cadmium, Zinc and Copper in high proportion. These metals are toxic and may cause severe problem with prolonged exposure. Monitoring the accumulation of these metals in soil samples is very important and the practice of cultivating the land for planting vegetables and legumes by farmers around the dumpsites must be discouraged to prevent the transportation of these toxic metals into human system.