Nitrate pollution in ground water of kalpitiya: An evaluation of the content of nitrates in the waterand food items cultivated in the area

A high intake of nitrates or nitrites is known to be hazardous to health. An analysis of drinking water from 225 wells in 11 Family Health Worker Areas in the Kalpitiya peninsula showed that only 56% of these wells contain nitrate concentrations considered to he safe by the WHO (< 50mg nitrate/1). 31% percent of these wells contain a nitrate concentration between 50mg/1 and 100mg/1 while the balance 17.4% contain very high nitrate concentrations ranging from 101-300 mg/1. An analysis of 7 types food items commonly grown in the peninsula (sweet potato-Ipomaea batatas, kurathampala-Amaranthus viridis, gherkins-Cucumis sp, anguna leaves-Timonius jambosella, red onions-Allium cepa, potatoes-Solanum tuberosum and long beans-Vigna cyindrica) revealed that anguna leaves, long beans and kurathampala contain high nitrate concentrations (2.79g/kg, 1.15g/kg and 3.25g/kg respectively) on a wet weight basis. Of these, anguna leaves is one vegetable known to be eaten daily by majority of the local population. From calculations based on the average daily intake of anguna leaves (approximately 100g) and water (31) it is apparent that a person living in an area with wells containing >100mg nitrate/1 would consume close to 600mg nitrate/ day. If the contribution from other vegetables consumed is also taken in to account, the daily nitrate intake of these individuals would be even higher. Therefore it is possible that high nitrate levels in the vegetables grown and water available in the Kalpitiya peninsula may attribute to the development of toxic methae-moglobinaemia in people living in the area.