Chioma, O. et al. 2017. Accumulation and toxicological risk assessment of Cd, As, Pb, Hg, and Cu from topsoils of school playgrounds at Obio-Akpor LGA Rivers State Nigeria. International Journal of Scientific World. 5, 1 (Jan. 2017), 38–46. DOI:https://doi.org/10.14419/ijsw.v5i1.6710.