More than 16 states in India are facing the fluorosis problem. Several southern-peninsular states are experiencing monsoon climate condition, where the rainwater is harvested through tanks and used for agriculture.
Presence of millions of such tank systems in these regions and their interception in the fluoride cycle has been studied here on a pilot level in several tanks. The results show that these tanks probably acting as sinks and cause the enrichment of fluoride in groundwater. The leachable fluoride level of tank silt is found to be several-fold more than that of normal land soil of the area. With the aging of the system and increase in thickness of fluoride laden tank silt, the rejuvenation of tank capacity through desilting and the practice of spreading silt in agricultural fields and further irrigating with fluoride enriched groundwater, make fluoride enter in a vicious cycle in the environment and food chain thus causing great concern.
Safe disposal mechanisms of fluoride laden silt to end the cycle for safeguarding the groundwater used for drinking in the SAT regions are suggested here. One of the environmental health issues connected with geogenic processes is excess fluoride in groundwater. Its ingestion through drinking and agricultural products leading to dental and skeletal fluorosis of hard-rock-covered SAT regions in India is severe, though the problem prevails in more than 25 countries of the world.
As per the study, the key to minimizing the risk is to incorporate hydrogeological, geochemical and microbiological expertise into the decision-making process in the rejuvenation of old irrigation tanks in fluoride rich regions with the safe disposal methods. Planners, managers, pollution regulation specialists and the community have to work in tandem with earth scientists to save the environment for the future generation. It is also essential to demarcate the high-risk areas and provide them with alternative sources of drinking water as an immediate measure.