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

Abstract

Drinking water contamination by nitrates poses serious health risks, particularly to infants and pregnant women. Rapid urbanization in Sango, alongside poor sewage and industrial waste management, intensifies nitrate pollution, endangering public health. The aim of this research is to assess the nitrate concentration in drinking water sources in Sango area of Ibadan metropolis. Twenty-two sampling points (SW1–SW22) were selected using stratified sampling. Water samples were collected during both rainy and dry seasons. Nitrate concentrations and key physicochemical parameters pH, temperature, turbidity, dissolved oxygen (DO), and electrical conductivity (EC) were measured. Daily nitrate intake was estimated across age groups and compared with WHO guidelines. Nitrate levels ranged from 125 - 285 mg/L (rainy season) and 67.42 - 153.67 mg/L (dry season), significantly above 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 thresholds, indicating significant health risks. The total nitrate intake across body weight categories exceeded WHO's estimated acceptable nitrate intake (mg/kg) in both rainy and dry seasons. Elevated levels, especially during the rainy season, pose significant health risks, surpassing WHO limits across demographics and seasons. Enhancing water treatment infrastructure, promoting rainwater harvesting, and improving filtration systems during periods of peak contamination can significantly reduce nitrate exposure.