Nitrate and nitrite levels in our natural water supplies are important indicators of water quality. The increasing levels of nitrate and nitrite concentrations are becoming an important problem for public health. Nitrates are of great toxicological concern as they are involved in the origin of nitrites and nitrosamines and the development of metahaemoglobinaemia in infants. The aim of this study was to determine the levels of nitrate and nitrite in commonly consumed mineral water samples in the Afyonkarahisar region of western Turkey. Thirteen brands of domestic fruity and natural mineral waters were analyzed to determine nitrate and nitrite levels. Measurement of the color intensity was carried out using a photometry at 540 nm and comparing it to standard nitrate and nitrite solutions. Average nitrate concentrations of 3.093 +/- 1.53 mg/L (range 1.02-7.50 mg/L) for fruity, and 3.990 +/- 2.46 mg/L (range 1.09-13.20 mg/L) for natural mineral waters, were detected. Regarding nitrite, average concentrations were 0.020 +/- 0.007 mg/L (range 0.009-0.049 mg/L) for fruity and 0.026 +/- 0.008 mg/L (range 0.008-0.087 mg/L) for natural mineral waters. According to the results of the present study, nitrate and nitrite levels in the fruity and natural mineral waters were not found in concentrations considered to be hazardous in terms of public health. (c) 2007 Published by Elsevier Inc.