Health Risk Assessment of Nitrate Contamination in Groundwater in Urban Informal Settlements in Kisumu, Kenya

Abstract

Background Groundwater is increasingly being used as a primary source of water for domestic use in low- and middle-income countries worldwide. This water is vulnerable to nitrate contamination due to a variety of factors, the most significant of which are excessive nitrogen-based fertilizer use and widespread onsite sanitation (use of pit latrines). Increase of nitrate concentration in groundwater has become a global concern in recent years. Prolonged nitrate exposure can cause a number of non-communicable diseases. Objective The objective of this study was to determine the nitrate concentration in various groundwater sources (wells and springs) and to calculate the health risk of exposure among residents as an indicator of public health impact. Methods This was a cross sectional study on informal settlements in urban and peri urban areas of Kisumu County. The study was conducted in urban and peri urban informal settlements within Kisumu County. Groundwater sources were identified using the snowball method while households were selected using simple random sampling. A structured questionnaire was used to collect data among heads of households. Water samples were analysed to determine their nitrate levels. The chronic daily intake (CDI) and hazard quotient (HQ) were used to assess human health risk.

Results Nitrate levels in 26.6% (n=45) of the groundwater sources were above the WHO recommended cut-off. Prevalence of diabetes and hypertension was 4% (n=299) and 19% (n=299) within this community. The chronic daily index was 0.189 mg/kg/day while the hazard index was 0.118. Conclusion The presence of nitrate in groundwater was contributed by pit latrines and use of fertilizers in the urban and peri-urban settlements respectively. Since the hazard index is less than one, the population is currently at low risk of disease. Recommendation The management of groundwater in the area and the implementation of preventive measures to stop further pollution will benefit from the study’s findings because doing so is essential for longterm sustainability.