Context:
Recently,A pan-India analysis found excessive fluoride levels in groundwater across states like Rajasthan, Telangana, Andhra Pradesh, Karnataka, Haryana, Gujarat, Madhya Pradesh, Tamil Nadu, Uttar Pradesh, Jharkhand, Bihar, and Chhattisgarh.
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- The analysis was based on 6.66 lakh observations.
- Fluoride contamination is caused by the leaching of fluoride-bearing minerals from aquifers into groundwater.
- The highest fluoride contamination occurs in dry, summer pre-monsoon months, with levels 8.65% above the permissible limit.
- Contamination remains high in post-monsoon months, 7.1% above normal.
- Excess fluoride can cause skeletal fluorosis, dental decay, and other health risks, especially in children.
- The permissible fluoride limit in drinking water is 1.50 mg/liter; levels above this are unfit for drinking.
- The average fluoride concentration is higher in dry, western India, with Rajasthan showing the highest contamination levels.
- Jaisalmer district in Rajasthan had the worst fluoride contamination in groundwater.
- Other states with above-normal post-monsoon fluoride concentrations include Karnataka, Tamil Nadu, and Jharkhand.
- Fluoride levels above 2% increase the risk of skeletal fluorosis, while levels above 40% can cause dental decay.
- Factors like lithology, soil type, geomorphology, and climate influence fluoride contamination, with arid and dry regions, especially in western India, being more affected.
Groundwater Availability in India:
- As of April 2015, India’s water resource potential is 1,869 BCM/year, (billion cubic meters) with usable resources at 1,123 BCM/year.
- Out of 1,123 BCM/year, 690 BCM is from surface water, and 433 BCM is from groundwater.
- After accounting for 35 BCM for natural discharge, net annual groundwater availability is 398 BCM.
- Rainfall contributes 68% to annual groundwater resources, with other sources (canal seepage, irrigation return flow, etc.) contributing 32%.
Declining Per Capita Water Availability:
- National per capita water availability has decreased from 1,816 m³ in 2001 to 1,544 m³ in 2011, a 15% reduction due to population growth.
Groundwater Development:
- Groundwater development refers to the ratio of annual groundwater extraction to its annual availability.
- High groundwater development (>100%) in states like Delhi, Haryana, Punjab, and Rajasthan, meaning extraction exceeds recharge.
- States like Himachal Pradesh, Tamil Nadu, Uttar Pradesh, and Puducherry have development levels over 70%.
- The national level of groundwater development increased from 58% in 2004 to 62% in 2011.
Other heavy metals that contaminate groundwater and their impacts include:
| Heavy Metal | Impacts |
| Zinc | Gastrointestinal disturbances, anemia, impaired immune function, lower cholesterol levels, pancreatic impact. |
| Arsenic | Skin lesions, cancer, developmental effects, cardiovascular disease, diabetes. |
| Nickel | Allergic reactions, lung and nasal cancers, dermatitis, respiratory and cardiovascular issues. |
| Copper | Gastrointestinal issues, liver damage, kidney problems, anaemia, neurological damage. |
| Cadmium | Kidney damage, bone disease, respiratory issues, cardiovascular diseases, carcinogenic. |
| Mercury | Nervous system damage, tremors, memory loss, cognitive impairments, kidney damage, developmental issues in children. |
| Chromium (Hexavalent) | Respiratory problems, skin irritation, lung cancer, kidney damage, carcinogenic. |
| Lead | Brain development issues in children, learning disabilities, behavioural problems, anaemia, kidney damage, hypertension. |