Health Risk Assessment of Nitrate Concentration in Soil and Water within the Sango area, Ibadan

Abstract

Nitrate contamination in drinking water sources poses significant health challenges globally, particularly in rapidly urbanizing areas. The problem of nitrate pollution in the Sango area of Ibadan metropolis has intensified due to poor sewage management and industrial waste discharge, creating serious public health concerns. This research aims to assess the nitrate concentration in drinking water sources in the Sango area of Ibadan metropolis. Twenty-two sampling points (SW1 -SW22) were selected using stratified sampling comprising 15 shallow wells, 4 boreholes, and 3 surface water sources distributed across residential, commercial, and mixed-use areas. Water samples were collected during both rainy and dry seasons. Physicochemical parameters, including nitrate concentration, pH, temperature, turbidity, dissolved oxygen, and electrical conductivity, were measured. Daily nitrate intake was estimated across age groups and compared with WHO guidelines. Nitrate levels ranged from 125 to 285 mg/L (rainy season) and 67.42 to 153.67 mg/L (dry season), significantly exceeding the WHO limits. pH ranged from 6.1 -9.3 and 6.32 -9.47; turbidity, 28.6 -49.3 NTU and 20.34 -34.54 NTU; DO, 5.02 -8.9 mg/l and 4.54 -7.63 mg/l; EC, 206.4 -907.5 μS/cm and 230.72 -980.44 μS/cm during rainy and dry seasons, respectively. Estimated nitrate intake across all adult age groups exceeded the WHO acceptable daily intake, indicating significant health risks. Elevated levels, especially during the rainy season, pose considerable health risks, surpassing WHO limits across seasons. Enhancing water treatment infrastructure and improving filtration systems during periods of peak contamination can significantly reduce nitrate exposure