TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: Fluoride contamination in groundwater has emerged as a significant environmental and public health issue in India, with several states experiencing levels far above the permissible limits.
EXPLANATION:
- The National Remote Sensing Centre (NRSC), part of the Indian Space Research Organisation (ISRO), has conducted a comprehensive analysis of fluoride contamination in the country, revealing alarming findings.
- This study offers valuable insights into the extent, distribution, and potential health risks associated with fluoride contamination, particularly focusing on Rajasthan and other affected regions.
Extent and Distribution of Fluoride Contamination
- The NRSC study examined 666,000 observations across India to determine the extent of fluoride contamination in groundwater.
- The analysis found that states like Rajasthan, Telangana, western Andhra Pradesh, eastern Karnataka, and parts of Haryana, Gujarat, Madhya Pradesh, Tamil Nadu, Uttar Pradesh, Jharkhand, Bihar, and Chhattisgarh have fluoride levels exceeding the permissible limits.
- Fluoride, while naturally present in groundwater due to the leaching of minerals, poses a health risk when its concentration surpasses 1.50 milligrams per litre, the nationally accepted limit for safe drinking water.
- Rajasthan, particularly the Jaisalmer district, has emerged as the worst-affected region in India.
- The study found that the average fluoride concentration in Rajasthan’s groundwater during the pre-monsoon season was 1.41 mg/litre, rising slightly to 1.44 mg/litre post-monsoon.
- These values are perilously close to the maximum permissible limit, indicating a significant health hazard for residents.
- The high levels of fluoride in Rajasthan can be attributed to the region’s arid conditions, which exacerbate the leaching and dissolution of fluoride-bearing minerals into the groundwater.
Seasonal Variations in Fluoride Levels
- The NRSC study highlighted significant seasonal variations in fluoride contamination.
- During the dry, summer pre-monsoon months (March-May), the fluoride concentration in India’s groundwater rose to 8.65 percent above the permissible limit.
- This increase is likely due to the higher rates of evaporation and reduced groundwater recharge, which concentrate the fluoride content.
- Even after the monsoon, when water tables are typically replenished, the fluoride levels remained high at 7.1 percent above normal, indicating persistent contamination issues.
Health Risks Associated with Excess Fluoride
- Excessive fluoride intake poses serious health risks, particularly affecting bone and dental health.
- The study pointed out that even fluoride concentrations as low as 2 percent can increase the risk of skeletal fluorosis, a condition that causes pain and damage to bones and joints.
- Higher concentrations, up to 40 percent, can accelerate dental decay, posing a significant threat to children who are more susceptible to fluoride toxicity.
- These health concerns underscore the urgent need for effective monitoring and mitigation strategies to protect public health.
Factors Contributing to Fluoride Contamination
- The study identified several natural factors that contribute to the high fluoride levels in groundwater.
- Lithology (the study of the physical characteristics of rocks), soil type, geomorphology (the study of landforms), and lineaments (linear features in the landscape that indicate underlying structural weaknesses) play crucial roles in the dissolution and distribution of fluoride-bearing minerals.
- Furthermore, the climatic conditions significantly influence fluoride contamination levels.
- Arid and semi-arid regions, such as those in western India, experience higher levels of fluoride contamination due to limited water availability and high evaporation rates, which concentrate fluoride in the remaining groundwater.
Lower Contamination in Humid Areas
- In contrast, regions with humid and wet climates exhibit relatively lower fluoride contamination levels.
- The higher rainfall and greater availability of water help dilute fluoride concentrations, reducing the risk of contamination.
- This geographical variation highlights the importance of tailored regional strategies to manage and mitigate fluoride contamination effectively.
National Remote Sensing Centre (NRSC)
- The National Remote Sensing Centre (NRSC) is a prominent institution under the Indian Space Research Organisation (ISRO), located in Hyderabad, Telangana.
- Established in 2008, NRSC evolved from the earlier National Remote Sensing Agency (NRSA), which was founded in 1974.
- The centre specializes in remote sensing data acquisition, processing, and dissemination, primarily focusing on Earth observation to support various national objectives, including disaster management and environmental monitoring.
- RSC manages data from both aerial and satellite sources, serving as a crucial hub for Earth observation data. It operates a data reception station at Shadnagar, which receives data from Indian and foreign remote sensing satellites