FLUORINE

FLUORINE Fluorine is a common element that does not occur in the

elemental state in nature because of its high reactivity

Accounts 0.3 g/kg of the Earth’s crust

Fluorides minerals are fluorspar, cryolite

and fluorapatite are the most common

oxidation state of the fluoride ion is-1.

PROPERTIES OF FLUORINE univalent poisonous gaseous halogen

Pale yellow-green most chemically reactive and electronegative of all the elements.

readily forms compounds with most other elements, even with the noble gases krypton, xenon and radon

In aqueous solution, fluorine commonly occurs as the fluoride ion F-

MAJOR USES

Inorganic fluorine compounds are used in industry for a wide range of purposes

used in aluminium production

Fluorosilicic acid, sodium hexafluorosilicate and sodium fluoride are used in municipal water fluoridation schemes

FLUORINE IN THE ENVIRONMENT

Annual world production of the mineral fluorite in around 4 million tons

Mining areas for fluorite are China, Mexico and Western Europe

occurs naturally in the earth's crust

13th most abundant element in the Earth's crust

Hydrogen fluorides can be released into air through combustion processes in the industry.

Fluorides that are found in air will eventually drop onto land or into water.

When fluorine is attached to very small particles it can remain in the air for a long period of time.

Atomic fluorine and molecular fluorine are used for plasma etching in semiconductor manufacturing

Fluorine is indirectly used in the production of low friction plastics such as Teflon

Fluorochlorohydrocarbons are used extensively in air conditioning and in refrigeration.

Fluorides are often added to

toothpaste

MINERALS CONTAINING FLOURINE Fluorspar (CaF2) is the principal

fluorine-containing mineral. It has fluorine content of 48.5%.

The world production of fluorspar in 1979 was estimated to be 4 866 000 tones (US Bureau of Mines, 1980).

In 2010, China produced three million tons of , sharing 55.6% of the global total.

Cryolite (Na3AlF6) is a relatively rare mineral that is an essential raw material in the aluminum industry; it has a fluorine content of 545 g/kg.

The formerly important cryolite deposits of Greenland are now almost exhausted; today most supplies have to be prepared synthetically (US NAS, 1971).

Fluorapatite,  common phosphate mineral, a calcium fluoride phosphate, Ca5(PO4)3F.

It occurs as minute, often green, glassy crystals in many igneous rocks, and also in magnetite deposits, high-temperature hydrothermal vents , and metamorphic rocks.

It has Fluorine content of 38g/kg

Rock phosphate is of great environmental significance as it is the source of fluoride in some areas of endemic fluorosis.

Its vast quantities are mined and consumed in the production of elemental phosphorus, phosphoric acid, and phosphate fertilizers.

SOIL: The fluorine in soil originates from rocks which are parent

materials of most of minerals components of soil, from plant and animal debris that supplies the organic matter of the soil, and from rain water falling upon it.

The amount of fluoride in soil depends on soil type, pH, salinity and fluoride concentration.

Soils contain approximately 330 ppm of fluorine, ranging from 150 to 400 ppm.

Some soils can have as much as 1000 ppm and contaminated soils have been found with 3500 ppm.

AIR:

The aerial emission of fluoride in the form of volcanic ash during volcanic eruption, fly ash from the combustion of fossil fuels result in air enrich with fluorine.

Natural background concentrations are of the order of 0.5 ng/m3. If anthropogenic emissions are included, worldwide background concentrations are of the order of 3 ng/m3.

In the Netherlands, concentrations in areas without sources are 30–40 ng/m3, rising to 70 ng/m3 in areas with many sources .

In some provinces of China, fluoride concentrations in indoor air ranged from 16 to 46 µg/m3 owing to the indoor combustion of high-fluoride coal for cooking and for drying and curing food.

FLUORINE IN WATER

SOURCES Weathering of rocks rich in fluoride(granitic rocks ,volcanic

rocks )

Hydrogen fluorine is one of the most soluble gases in magmas and comes out partially during eruptive activity (dalessandro, 2006)

Leeching of industrial discharges , volcanic ash, fertilizers etc.

CONCENTRATIONS

Fertilizers containing leachable fluoride ranging from 53 to 255 mg/kg

Coal containing fluoride ranging from 5 to 20 mg/kg

Polluted groundwater with high fluoride in east Punjab, Pakistan by Farooqi et al. (2007)

Fluoride con. in the groundwater of some villages in China were greater than 8 mg/liter

Granitic rocks contain fluoride ranging between 500 and 1400 mg/kg

The fluoride content in ash from Hekla eruption in 2010 was 23-35 mg/kg

FOODS & PLANTS

All foodstuffs and plants contain at least traces of fluorine

Absorbed from soil and water through the roots and through the leaves

The highest levels are found in curly kale (up to 40 mg/kg fresh weight) and endive (0.3–2.8 mg/kg fresh weight)

Levels in dry tea can be 3–300 mg/kg so 2–3 cups of tea contain approximately 0.4–0.8 mg (IPCS, 1984; slooff et al., 1988)

Ti (Cordyline fruticosa) is sort of famous for developing burnt tips and margins from fluoride

ESTIMATED TOTAL EXPOSURE AND RELATIVE CONTRIBUTION OF DRINKING-WATER Daily exposure to fluoride depend

geographical area.

In the Netherlands, the total daily intake is calculated to be 1.4–6.0 mg of fluoride.

From food 80–85%

From drinking-water is 0.03–0.68 mg/day

From toothpaste 0.2–0.3 mg/day

Daily intakes of fluoride vary widely according to the various sources of exposure.

Ranging from 0.46 to 3.6–5.4 mg/day

Intakes in areas where high-fluoride coal is used indoors or where there is elevated fluoride in drinking-water can be significantly higher

in some counties in China where coal has a high fluoride content the average daily intake of fluoride ranged from 0.3 to 2.3 mg via air and from 1.8 to 8.9 mg via food (Cao et al., 1992).

In areas with relatively high fluoride concentrations in

groundwater, drinking-water becomes increasingly important as a source of fluoride.

Daily exposure in volcanic areas with high fluoride levels in drinking-water may be up to 30 mg for adults, mainly from drinking-water intake.

ENVIRONMENTAL EFFECTS OF FLUORINE

When fluorine from the air ends up in water it will settle into the sediment. When it ends up in soils, fluorine will become strongly attached to soil particles.

In the environment fluorine cannot be destroyed; it can only change form.

Fluorine that is located in soils may accumulate in plants. The amount of uptake by plants depends upon the type of plant , type of soil and the amount and type of fluorine found in the soil.

IN PLANTS

With plants that are sensitive for fluorine

exposure even low concentrations of fluorine

can cause leave damage

Too much fluoride retards the growth of plants and reduces crop yields.

Those more affected are corns and

apricots.

IN ANIMALS Animals that eat fluorine-containing plants may

accumulate large amounts of fluorine in their bodies.

Fluorine accumulates in bones. Consequently, animals that are exposed to high concentrations of fluorine suffer from dental decay and bone degradation.

Fluorine can also cause low birth-weights.