definition 112 causes, effects and control measures of

5.5 POLLUTION CASE STUDIES

A case study of groundwater pollution in

India

An example of groundwater pollution caused

by excessive extraction is that fluoride contami-

nation. Fluorisis is not a localized problem. It has

spread across 19 states and across a variety of

ecological regions ranging from the Thar desert,

the Gangetic plains and the Deccan plateau.

Each of these regions are distinct in terms of

rainfall, soil type, groundwater recharge regime,

climatic conditions and hydrology. High fluoride

concentration in groundwater is a natural phe-

nomenon in several countries such as China, Sri

Lanka, West Indies, Spain, Holland, Italy and

Mexico. Experts claim that a fluoride belt

stretches across the Middle East across Pakistan

and India and then into Southeast Asia and the

South of China. According to a report of the

Rajiv Gandhi National Drinking Water mission,

the bedrock of the Indian peninsula consists of

a number of fluoride bearing minerals. When

the bedrock weathers the fluoride leaches into

water and the soil. Although the Indian penin-

sular bedrock has always been the same, this

problem has only surfaced during the last three

decades. This is related to the over extraction of

groundwater which has resulted in the tapping

of aquifers with high fluoride concentrations.

The beginnings of this phenomenon can be

traced back to the 1970s and the 1980s when

there was massive state investment in rural

water development for irrigation as well as for

drinking. Encouraged by state subsidies on die-

sel and electricity, people invested in diesel and

submersible pumps in a bid to extract ground-

water through borewells. This policy aggravated

the fluoride problem.

Fluoride mainly enters the human body through

drinking water where 96 to 99 percent of it

combines with the bones as it has an affinity for

calcium phosphate in the bones. Excess intake

of fluoride can lead to dental fluorosis, skeletal

fluorosis or non-skeletal fluorosis. Dental fluo-

rosis is characterized by discoloured, blackened,

mottled or chalky white teeth. Skeletal fluorosis

leads to severe and permanent bone and joint

deformities. Non-skeletal fluorosis leads to

gastro-intestinal problems and neurological dis-

orders. Fluoride can damage the foetus and

adversely affect the IQ of children.

Once fluoride is detected in water, the only so-

lution is to deflouridate it. Various technologies

are available for this process. However the type

of technology to be selected depends upon the

fluoride levels in the water and the volume of

water to be deflouridated. None of the Indian

technologies are however fool-proof.

Deflouridation plants and household water treat-

ment kits are stop-gap solutions.