Evaluating the Levels and Human Health Risks of Heavy Metals in Soils around Onne Landfill, Rivers State, Nigeria

This study evaluated selected heavy metals’ levels in soil around the landfill in Onne Rivers State, Nigeria. It also examines potential human health risks due to exposure to the contaminated soil. Composite samples of soils from the northern, southern, eastern and western domains of the landfill were collected, processed, and analysed for heavy metals using atomic absorption spectrophotometry, and their human health risks were evaluated. The heavy metals’ levels in the soils around the four domains were in the order Pb>Cr>Ni>Cd>As. Children and adult ingestion, inhalation and dermal hazards quotients for the selected metals in the four domains were below unity ranging from {(HQchildren 2.71 x 10-10 As inhalation in the eastern domain to 9.24 x 10-1 Pb ingestion in the northern domain); HQadult 1.55 x 10-10 As inhalation in the eastern domain to 9.90 x 10-2 Pb ingestion in the northern domain)}. Adult ingestion, inhalation and dermal cancer risks (CRadult) were within acceptable limits, ranging from 1.99 x 10-13 As inhalation in the eastern domain to 4.68 x10-5 Cr ingestion in the northern domain. However, ingestion cancer risk for children (CRchildren) due to exposure to Ni and Cr in the four domains were above tolerable limit ranging from {(Ni - 2.00 x 10-4 in the southern domain to 3.11 x 10-4 in the northern domain); Cr – 2.95 x 10-4 in the southern domain to 4.37 x 10-4 in the northern domain)}. Children and adult hazards index due to exposure to the selected metals were also less than 1.0, ranging from children exposure to Ni (5.91 x 10-3) in the southern domain and Pb (9.25 x 10-1) in the northern domain to adult exposure to Ni (6.50 x 10-4 in the southern domain and Pb (9.94 x 10-2) in the northern domain. Total cancer risks (TCRadult) due to adult exposure to the metals were within tolerable limit, ranging from Cd (4.93 x 10-7) in the southern domain to Cr (5.01 x 10-5) in the northern domain. And total cancer risk (TCRchildren) due to children exposure to Ni and Cr were above tolerable limit, ranging from {Ni (2.40 x 10-4 in the southern domain to 3.74 x 10-4 in the northern domain); Cr (3.54 x 10-4 in the southern domain to 5.24 x 10-4 in the northern domain)}. The values for both non carcinogenic and carcinogenic risks were higher for children than those for adult. Reasons for this attributes and improvement actions were suggested.