Evaluation of Groundwater Quality Using Nitrate Pollution Index and the Potential Health Risk Method in Guenniche Basin of Northern Bizerte (Tunisia, North Africa)

Human intervention has produced groundwater pollution in alluvial aquifers, affecting the health of the exposed people. Twenty (20) samples of shallow groundwater in Bizerte's Guenniche basin (North Tunisia) were assessed, aiming to estimate the nitrate pollution index (NPI) and possible non-carcinogenic risks (N-CR) to human health based on the nitrate results. The NO3− findings reveal that 50% of the total samples exceeded both limits (NT and WHO set at 45 and 50 mg.L−1, respectively) with concentrations ranging from 3.07 to 990 mg.L−1. The well containing the highest NO3− levels (990 mg.L−1) is located near cattle stalls, which resulted from solute propagation caused by animal-manure transport phenomena. The NPI varied between – 0.85 and 48.56, with a mean of 6.17, suggesting that the sampled wells were classified: 50% as “Very Significant” pollution, 5% as “Significant” pollution, and 45% between “Light pollution” to “Clean water”. The NO3− daily average intake by ingestion pathway (DAI) in mg.kg−1.day−1 ranged from 0.09 to 29.72 for adults and 0.23 to 74.31 for children, concluding that the DAI in 11 wells for adults and 13 wells for children exceeded the reference dose set at 1.6 mg.kg−1.day−1. The N-CR for adults and children varied from 0.06 to 18.57 with a mean of 2.68 and from 0.14 to 46.44 with a mean of 6.72, respectively. Comparing the N-CR with the standard limit set at one (1) submitted by USEPA, the same wells as the DAI for both age brackets were of an alarming potential risk. Children's potential health risk (DAI and N-CR) was ~ 2.5 times greater than that of adults. Children are more vulnerable to the effects of contaminated water. The study area is dominated by nitrate contamination. As a result, appropriate actions must be implemented to increase awareness within the Guenniche community and to establish a long-term program aimed at decreasing the nitrate-contaminated in this shallow groundwater to seek to lessen health hazards to its users.