Estimation of radiological impact of the activities of Olusosun Dump Site on workers and dwellers of Olusosun, in Lagos Southwest Nigeria

This study assessed the potential radiological risks associated with the activities on Olusosun dump site on workers and dwellers of Olusosun community. The activity concentrations of U-238, Th-232 and K-40 from of soil and water samples were determined using High-Purity Germanium (HPGe) detector. The background radiation level of Olusosun dump site was measured using a portable Geiger-Muller counter-Radeye B20 survey meter. The mean value of background radiation was 1.46 mSv/yr. This value is about 46% higher than the recommended reference level of 1.0 mSv/yr for the public. The mean activity concentrations of U-238, Th-232 and K-40 in the soil samples were 19.1 +/- 3.2, 29.1 +/- 4.4 and 171.5 +/- 6.1 Bq/kg respectively which are about 45.4%, 35.3% and 59.2% lower than the world's average levels. For the water samples, the mean activity concentrations obtained for U-238, Th-232 and K-40 are 0.4 +/- 0.4, 0.8 +/- 0.2 and 0.8 +/- 0.3 Bq/l respectively. These are about 99.9% and 20% lower than WHO reference levels for U-238 and Th-232. The mean absorbed dose rate in air (D), Annual effective dose (AED) outdoor, Radium Equivalent (R-eq), External hazard index (H-ex) internal hazard index (H-in) and Excess lifetime cancer risk (ELCR) from soil samples were 33.6 nGy/h, 41.0 mu Sv/yr, 73.1 Bq/kg and 0.2, 0.3 and 1.4 x 10(-4), respectively. Absorbed dose in air D, AED outdoor, R-eq, H-ex, H-in and ELCR are 41.1%, 41.4%, 80.3%, 80%, 75% and 50% lower than their corresponding world's average and references. The estimated AEDw from ingestion of water is 148.9 +/- 50.4 mu Sv/yr, this is about 49% higher than the WHO reference level of 100.0 mu Sv/y from ingestion of water. The radiological hazard indices estimated from soil samples do not indicate any potential risks to the users. The elevated background radiation level of the dump site, and AEDw from ingestion of water, however, suggest that the activities on Olusosun dump site pose potential radiological risks on workers on the site and the public from consumption of water from Olusosun community.