Fluoride In Natural Waters And  Health Hazards
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Fluoride In Natural Waters And Health Hazards

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Fluoride In Natural Waters And  Health Hazards Fluoride In Natural Waters And Health Hazards Presentation Transcript

  • FLUORIDE IN NATURAL WATERS AND HEALTH HAZARDS by SK SABUR ALI UG-III, ROLL-000620401019 JADAVPUR UNIVERSITY Email ID: sabur.ju@live.com
  • Fluorine
    • Element of halogen group.
    • Atomic number 9 , Atomic wt. 19.
    • Most electronegative element.
    • Ionic radius similar to (OH) -.
    • Low dissociation energy (38kcal/mole)
  • Sources of F in natural water
    • Natural :
    • Igneous rocks/mineralized veins
    • Sedimentary formation
    • Water from Geothermal areas/hot spring.
    • Volcanic emission, evaporation, marine aerosols.
    • Anthropogenic :
    • Industrial aerosol, coal burning, brick making, aluminum smelting, introduction of CFC.
    • Fertilization with super phosphates (ATSDR, p146).”
    • Fluoridation of low fluoride concentration water.
  • Release of fluorine in water during weathering of rocks
    • Abundance of fluorine in the rocks.
    • Controlled by solubility product.
    • For fluorite, CaF 2 =Ca ++ +2F −
    • K fluorite =(Ca ++ ).(F − ) 2 =10 -10.57 at 25 ◦ c.
    • inversely proportional to Ca ++ concentration.
    • 2Na + ->Ca ++ increases fluoride concentration.
    • Longtime water-rock interaction.
    • Positive correlation with temp & depth
    • & negative correlation with hardness of water.
    • High in neutral to alkaline water (pH 7-9).
  • Health hazards
    • Fluoride enters the human body by ingestion (food and water), and in extreme cases through the skin.
    • The maximum permissible limit of Fluoride content in groundwater is 1.5 mg/l (WHO, 1994). For the Indian sub-continent, the desirable limit of ‘F’ is 0.6 mg/l and maximum permissible limit is 1.2 mg/l (ISI, 1983).
    • Low concentration causes dental caries
    • High concentration promotes dental fluorosis, skeletal fluorosis, crippling fluorosis. Ca 10 (PO 4 ) 6 (OH) 2 ->Ca 10 (PO 4 ) 6 (F) 2
  • Non skeletal health hazards
    • Destruction of stomach & intestinal lining (mucosa). F − +HCl =HF+Cl −
    • High concentration causes Nervousness & Depression, Muscle Weakness & stiffness.
    • Early destruction of RBCs causes anemia.
    • soft tissues like ligaments, blood vessels tend to harden and calcify and the blood vessels may be blocked.
    • Excessive fluoride intake since early childhood would reduce mental work capacity (MWC) (case study).
    • May causes cancer (less clearly defined).
  • Remediation of high fluoride water
    • Identifying the source and mapping of affected area
    • Defluoridation of water containing excessive fluoride concentration.
    • Promote & support research & development on removal of excessive fluoride.
    • Develop suitable local guideline and standards of fluoride in drinking water.
    • Develop & survey alternative source of drinking water, such as rain water.
    • Detailed study on the vertical variation of the fluoride concentration and identify aquifers with less fluoride concentration–sealing aquifers with high fluoride concentrations
  • References
    • Edmunds M.,Smedley p.(2004);Fluoride in natural waters, in Selinus O., Alloway B.J. , Centeno J.A. , Finkelman R.B. , Fuge R. , Lindh U. , Smedley P. (eds) Medical geology; Elsevier; pp:812.
    • http://en.wikipedia.org/wiki/Fluoride
    • http://jdr.sagepub.com/
    • http://www.atsdr.cdc.gov/
    • http://www.webelements.com/
  • THANK YOU