Contamination of Nitrate in Groundwater and Evaluation of Health Risk in Bachok, Kelantan: A Cross-Sectional Study

Abstract

High concentrations of nitrate through drinking water have been associated with health problems. This cross sectional study sought to determine the level of nitrate concentrations in private well water and the association to the disease caused by nitrate among population of Bachok, Kelantan. The concentrations of nitrate in 256 wells were sampled from September to October 2015. About 126 respondents from the agricultural area and 130 respondents from the non-agricultural area were participated in the study. The human health risk associated with ingesting nitrate were assessed by Hazard Quotient (HQ) and Odd Ratio (OR). The physicochemical characteristics of well water in both areas (i.e., pH, ammonia, Dissolved Oxygen (DO), conductivity, turbidity, Total Dissolved Solid (TDS) and salinity) were within the acceptable limits of Malaysian Drinking Water Quality Standard. The mean ± SD levels of nitrate in the agricultural area was 13.04±14.39 mg L^-1 NO₃-N, exceeding the maximum acceptable limits of Malaysia NDWQS (10 mg L^-1 NO₃-N) and were two fold higher than the non-agriculture area (6.31±5.22 mg L^-1 NO₃-N). 52 wells (41.27%) in the agricultural area and 35 wells (26.9%) in the non-agricultural area had nitrate level above the maximum acceptable nitrate (10 mg L^-1 NO₃-N). The HQ associated with the potential non-carcinogenic risk of drinking nitrate contaminated groundwater ranged from 0.007 to 1.143×10^-6 in the agricultural area, slightly higher than in the non-agricultural area (0.002 to 0.468×10^-6). The OR for disease such as diabetes, goitre and gastric were not significant with high levels of nitrate in the well water. The results of the present study showed that there was no statistically significant association between nitrate in well water and the risk of related health disease such as diabetes, goitre and gastric in this study.