Fluoride levels in deep aquifers of Makurdi, North-central, Nigeria: An Appraisal based on multivariate statistics and human health risk analysis

Abstract

This study was conducted to investigate the ionic and fluoride concentrations in borehole water and its associated health risk potentials to residents of Makurdi town and its environs, Benue state, Nigeria. An aggregate of sixty-three (63) groundwater samples were retrieved from boreholes in twenty-one (21) diverse points within the study area and assessed for its physico-chemical composition with emphasis on fluoride content and health risk potentials following standard field and laboratory procedures. It was observed that fluoride content in the sampled water exceeded the stipulated safe limit of 1.5 mg/L in about 33.33% of the total samples and ranged from 0.34–2.06 mg/L with an average of 1.26 ± 0.41 mg/L. Moderate affirmative relationships were observed to exist between F− and TDS; F− and EC; F− and Cl−; F− and NO3− in the water samples indicative of a common source pollution. Principal Component Analysis (PCA) revealed that high fluoride content in the water samples was associated with the dissolutions from quartzite and shale into the underlying deep aquifers. Fluoride risk assessment indicated that the hazard quotient (HQ) for ingestion of fluoride laden water exceeded the threshold value in 66.7, 71.4, 52.4 and 9.5% of the samples for infants, children, teenagers, and adults respectively. It is concluded that groundwater in Makurdi is contaminated with excessive fluoride levels in most locations; hence, the findings of this study would serve as a basis for policy makers and regulatory bodies towards ameliorating the menace of groundwater contamination within the study area.