fluoride in natural waters and health hazards

FLUORIDE IN NATURAL FLUORIDE IN NATURAL WATERS AND HEALTH WATERS AND HEALTH

HAZARDSHAZARDS

by

SK SABUR ALIUG-III, ROLL-000620401019

JADAVPUR UNIVERSITY

Email ID: sabur.ju@live.com

FluorineFluorine

Element of halogen group. Element of halogen group.

Atomic number 9 , Atomic wt. 19.Atomic number 9 , Atomic wt. 19.

Most electronegative element.Most electronegative element.

Ionic radius similar to (OH)Ionic radius similar to (OH)-.-.

Low dissociation energy (38kcal/mole)Low dissociation energy (38kcal/mole)

Sources of F in natural waterSources of F in natural waterNaturalNatural::

Igneous rocks/mineralized veinsIgneous rocks/mineralized veins

Sedimentary formation Sedimentary formation

Water from Geothermal areas/hot spring.Water from Geothermal areas/hot spring.

Volcanic emission, evaporation, marine aerosols. Volcanic emission, evaporation, marine aerosols.

AnthropogenicAnthropogenic::

Industrial aerosol, coal burning, brick making, aluminum smelting, introduction Industrial aerosol, coal burning, brick making, aluminum smelting, introduction of CFC.of CFC.

Fertilization with super phosphates (ATSDR, p146).”

Fluoridation of low fluoride concentration water.Fluoridation of low fluoride concentration water.

Release of fluorine in water during Release of fluorine in water during weathering of rocksweathering of rocks

Abundance of fluorine in the rocks.Abundance of fluorine in the rocks.

Controlled by solubility product. Controlled by solubility product. For fluorite, CaFFor fluorite, CaF22=Ca=Ca+++++2F+2F−− K K fluoritefluorite=(Ca=(Ca++++).(F).(F−−))22=10=10-10.57-10.57 at 25 at 25◦◦c. c. inversely proportional to Cainversely proportional to Ca++++ concentration. concentration.

2Na2Na++→Ca→Ca++++ increases fluoride concentration. increases fluoride concentration.

Longtime water-rock interaction.Longtime water-rock interaction.

Positive correlation with temp & depth Positive correlation with temp & depth & negative correlation with hardness of water.& negative correlation with hardness of water.

High in neutral to alkaline water (pH 7-9).High in neutral to alkaline water (pH 7-9).

Health hazardsHealth 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. Ca10(PO4)6(OH)2→Ca10(PO4)6(F)2

Non skeletal health hazardsNon skeletal health hazardsDestruction of stomach & intestinal lining (mucosa). F−+HCl =HF+Cl−

High concentration causes 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 waterRemediation of high fluoride water Identifying the source and mapping of affected area

Defluoridation of water containing excessive fluoride concentration.Defluoridation of water containing excessive fluoride concentration.

Promote & support research & development on removal of excessive fluoride.Promote & support research & development on removal of excessive fluoride.

Develop suitable local guideline and standards of fluoride in drinking water.Develop suitable local guideline and standards of fluoride in drinking water.

Develop & survey alternative source of drinking water, such as rain 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

ReferencesReferences 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/