Fluoride and silicon intake in normal and endemic fluorotic areas

Precise quantitative information on (a) the contribution of diet to the daily intake of fluoride; and (b) the intake of silicon, which the current work suggests can aggravate fluorosis, is not available for fluorotic and non-fluorotic areas of India. Therefore, an attempt has been made in the present study to collect the above information in normal and fluorotic villages. The daily intake of fluoride (mean +/- SD) over water and diet in normal villages was 1.2 +/- 0.67 mg and 1.0 +/- 0.60 mg, while the corresponding values in a normal urban area were 0.5 +/- 0.03 mg and 1.2 +/- 0.73 mg, respectively. With respect to the intake over water the mean values in normal areas (urban vs. rural) were significantly different (P < 0.001), while there was no significant difference in dietary contribution in the normal areas. In fluorotic villages the daily intake of fluoride was 12.1 +/- 4.11 mg over water and 3.4 +/- 2.43 mg over the diet. These values from fluorotic villages were significantly higher (P < 0.001) than those observed in the normal rural areas. The total intake of silicon (mean +/- SD) in rural and urban normal areas was 204 +/- 58.6 mg and 143 +/- 29.4 mg per day, respectively. The corresponding value from fluorotic villages was 277 +/- 65.5 mg, which was significantly higher (P < 0.01) than those observed in both the normal areas. The situation was similar in fluorotic villages with respect to silicon intake over diet and water. However, the intake of this element over water in the normal rural area (74.0 +/- 18.51 mg per day) was significantly higher (P < 0.001) than the value obtained in the normal urban area (7.5 +/- 1.82 mg per day). This study clearly shows that in the fluorosis-affected areas studied, (a) the total intake of both fluoride and silicon is significantly higher than the intake in non-fluorotic areas; and (b) diets contribute significantly to the intake of both these elements. Our observations on silicon intake and its probable relation to fluorosis are the first of their kind in the literature.