Fluoride Toxicity in Rajasthan, India: Human Health Risk Assessment, Low-Cost Water Filter Preparation, and Contaminant Remediation

Abstract

The present study investigates fluoride concentrations from 9 locations in Rajasthan, India, and its associated health risk to the local inhabitants. pH, total dissolved solids (TDS), electrical conductivity (EC), chloride, hardness, and dissolved oxygen (DO) were among the other qualitative parameters measured, where the mean recorded values were 8.5, 723.9 mg/l, 1510 μS/cm, 462.63 mg/l, 32.3 mg/l, and 6.3 mg/l, respectively. All of the tested samples had fluoride above the threshold value. To assess the fluoride health risk, the average daily dosage (ADD) and ingestion hazard quotient (IHQ) were evaluated for residents for ages 1 to > 80. Further work developed a low-cost household water filter for efficient fluoride remediation. The design is a low-cost gravity water filter prepared with diverse raw materials such as cement, sand, clay, ceramic, sugarcane bagasse, sawdust, potato gel, and activated carbon. Eight filters using different combinations of raw materials—four each of cement and ceramic as the base material—were tested for quality and flow rates over 30 days. The mean discharges measured through filters ranged from 0.034 to 1.17 l/h, with fluoride removal efficiency varying from 23.53 to 67.64% for the cement filters and 29.41 to 37.53% for ceramic filters. With the switch from cement to ceramic as the raw material, the filters’ mean pore size varied from 1.432 to 0.013 μm. The per-area costs for the cement and ceramic filter ranged from INR 60.28 to 116.76 and INR 805.95 to 1023.90, respectively. The best filter combination was tested for field samples, with a fluoride removal rate of 88.55%.