Carcinogenic and Non carcinogenic Risk Assessments of Soil Samples Collected from Locally-Made Fertilizer Industries in Nigeria

Abstract

AbstractThe scarcity and high costs of fertilizers in Nigeria necessitated the production and use of local fertilizers using different types of soil. The evaluation of toxic metals in the local fertilizers is not underestimated due to the practical implications of heavy metals to health and environment. Human body is exposed to heavy metals through ingestion, inhalation and absorption through organs and systems of the body. This research is aimed to investigate the Carcinogenic and non-Carcinogenic Risk Assessment of Soil Samples Collected from Locally-Made Fertilizer Industries in Nigeria. The town of Kankara in Katsina state is one of the places with the highest number of industries that are producing the locally made fertilizers. The samples were collected from various local fertilizers industries in Kankara local government area, Katsina state, Nigeria. Three (3) samples from six different industries were collected. The samples were analyzed using Energy Disperse X-ray Fluorescence (EDXRF) and Atomic Absorption Spectroscopy (AAS) in order to determine the metal content in the samples. The results of mean heavy metals concentration level in the samples were Cr, Pb, Ni, Zn, and Cu are 23.14 (10.8 mg/kg), 65.53 (60.5 mg/kg), 26.93 (23.00 mg/kg), 34.2 (29.3 mg/kg) and 20.43 (13.2 mg/kg), respectively. These values are significantly lower than the permissible limits set by the World Health Organization. The mean results of Annual Daily Intake (ADI) for Cr, Pb, Ni, Zn, and Cu for child and adult across ingestion, inhalation, and dermal contact pathways, respectively reveal significant differences in potential exposure risks for children and adults. Among the metals studied, Cd exhibits the highest HQ for ingestion, with 3.82×10−6 for children and 2.09×10−6 for adults, while Pb, Zn and Cu show significantly lower values. The ingestion level shows the highest HI for children at 6.29E-01 (1.2014), followed by dermal contact at 8.99E-03 (2.1305), and inhalation at 10.00E-04 (4.0275E-06), for the black soil samples. For adults, the corresponding HI values are 2.57E-02 (1.0131) (ingestion), 6.13E-03(2.0032) (dermal), and 4.57E-06 (0.2000) (inhalation) of child (adult) for red soil samples. These values are all below the threshold value of 1, suggesting that non-carcinogenic risks are within acceptable limits. The carcinogenic risk is within the recommended limit. Remedy efforts are required, which includes; standard safety precautions such as use of face-masks and public health interventions to limit direct soil contact to reduce the associated health risks.

Keywords: Ingestion, Inhalation, Dermal and Carcinogenetic