Human Health Risk Assessment From Exposure To Microbial And Chemical Contaminants In Groundwater Sources Occuring In Tamale Metropolis, Northern Region

Abstract

Groundwater is a natural resource useful in sustaining human life and livelihoods. The rising urban population, rapid urbanisation, and changing biophysical factors increase water demand and quality. This study assessed the groundwaters microbial and physicochemical contaminants, chemical risk of exposure and susceptibility of Escherichia coli to antibiotics. Cluster and purposive sampling techniques were used to select 20 groundwater sources from the study sites. The membrane filtration technique, portable probe meter, turbidimeter and acetylene-to-air flame techniques were used for microbial and physico-chemical analysis. Data generated were subjected to descriptive statistics and one-way t-test. Of the 11 borehole water samples, 36.4%, 63.6%, and 72.7% were within the permissible limit for total coliforms, faecal coliforms and Escherichia coli, respectively. For the hand-dug well water samples, 66.6%, 66.6% and 44.4% were within the stipulated values for total coliforms, faecal coliform and E. coli, respectively. Concerning the physicochemical parameters, all but turbidity, Fe, Mn and Cd had 22.2%, 11.1%, 44.4% and 22.2% of samples falling within the expected values. About 77.8% of the borehole tested had normal level of turbidity, 27.27% for iron, 9.09% for manganese and 9.09% for cadmium. All borehole samples’pH, conductivity, Cu and Zn levels fell within the acceptable range. Regarding hand-dug well water, the computed hazard quotient for Cu, Fe, Mn and Zn were less than 1 for adults and infants, indicating no likely health threat. Adults and infants computed hazard quotients for the boreholes were less than 1 except for Fe and Mn among infants at two separate points. The hazard index exceeded one at four the borehole points indicating the possible cumulative potential of adverse health risk. Escherichia coli isolates were sensitive to Ciprofloxacin, Gentamicin and Ofloxacin whereas Cefuroxime, Augmentin and Ceftazidime were resistant. The presence of coliform bacteria and the deviation of the physicochemical indicators from the stipulated values in some of the water sources suggests existence of insanitary conditions and lithogenic factors. Appropriate treatment installation is recommended to help bring the quality of the water sources to an acceptable range. There is also a need for strict adherence to hygienic protocol and proper disinfection at hand-dug well and borehole facilities. E. coli infection resulting from consumption of the water sources surveyed may be managed effectively with Ciprofloxacin, Gentamicin and ofloxacin.