Pollution indices and health risk evaluation of heavy metals in a playground soil from Katsina State, Northwestern Nigeria

Abstract

The pollution indices and health risks to the population from exposure to heavy metals in a playground soil sample was carried out in the current study. The soil sample heavy metal concentrations were determined using Atomic Absorption Spectrophotometry. The heavy metals soil pollution indices were computed based on the Geoaccumulation index (Igeo),
enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and potential ecological risk index (PERI). The health risks of the evaluated heavy metals to the population were calculated using the Hazard Quotient (HQ) and Hazard Index (HI)) to assess the possible non-carcinogenic effect and the Incremental Lifetime Cancer Risk (ILCR) for the cancer risks. The results had revealed that all the evaluated heavy metals were within the regulatory bodies’ permissible limits. The I-geo values have revealed that the soil sample was unpolluted with these heavy metals. In addition, the heavy metal enrichment
factor (EF) shows a varying degree of enrichment; Fe and Mn (deficiency to minimal) Zn (Moderate), Ni (significant), Cr (extremely high). The result of the contamination factor has indicated that the soil sample in the study has low contamination by the heavy metals. The result of pollution load index was less than 1. With the potential ecological risk index (PERI)
values presenting low ecological risks. The calculated non-cancer risk indices in both the children and adult population for the heavy metals were below 1. The Incremental Life Cancer Risk (ILCR) for both the adult and children population has revealed that the heavy metal Ni was beyond the threshold of the safety range for cancer risk. The results of the pollution indices have indicated that the soil sample have low contamination, while the results for the health risk evaluation pointed to the possible contribution of exposure to the soil sample to heighten the risks for cancer in the population.