FLUORIDE CONCENTRATION IN GROUNDWATER IN THE NORTH 24-PARAGANAS DISTRICT OF WEST BENGAL, INDIA

One hundred and sixty samples of ground source drinking water were collected at different depths in the 24-Paraganas District of West Bengal and analysed for pH, electrical conductivity (EC), and fluoride (F). Nearly all the samples had pH similar to 7.0, low salinity (EC <1.0 ds/m), and low F (0.01-1.18 mg/L). While exhibiting little dependence on location or depth of sampling, only 2.5% of the samples contained more than 1.0 mg F/L that might pose a potential threat of endemic fluorosis. On the other hand, the F content in the water had a significant positive correlation (r = 0.16, p<0.05) with the amount of phosphate fertilizer use, thereby indicating its possible role in F enrichment of the groundwater. The threat of F toxicity exists for a few villages in the district.