Daily Monitor (Addis Ababa)
11 August 2007
An estimated 8.5 million people (12% of the total population) living in the
rift region in Ethiopia are at risk of an attack from fluoride, a chemical
substance which can become toxic when consumed in high concentration, a senior
expert at the Ministry of Mines and Energy disclosed on Thursday.
A high concentration of the substance in water used for domestic consumption becomes toxic and spoils the natural color and texture of human teeth.
"If the concentration exceeds 1.5 Mg/L, it would be chronically toxic'" Dr. Berhanu Gizaw, a geological survey expert said.
Studies indicate that the volcanic rocks of East Africa are found to be richer in fluoride than analogous rocks in other parts of the world.
The expert noted that the acidic rocks such as pumice deposits are likely sources for anomalous amounts of fluoride and sodium in the surface and ground water of the Ethiopian rift valley.
Other than the acid volcanic nature of rocks, on the other hand, the current understanding of high fluoride concentrations in the ground waters of the rift are believed to be enhanced due to the high co2 pressure; hydrothermal heating; and low calcium and low salinity fluids while high fluoride, salinity and alkalinity in closed- basin lakes is resulted from evaporative concentration, according to the expert.
Dr. Berhanu was presenting on the findings of his research at the Ethio-symposium organized by the Ministry of Mines and Energy.
He explained that Fluoride has various other impacts on health depending on the amount of concentration in the water supply.
The expert noted that if the amount of concentration is between the range of 1.5 and 3.5Mg/L, a kind of enamel hyperplasia known as Dental flourosis will occur when taken during the period of enamel maturing.
He said the result was a destruction of the ameloblasts and the production of abnormal mottled enamel.
"If it is between the range of 3.6- 10Mg/L , a kind of bone disease which alters the size and structure of its crystal , known as skeletal flourosis will result to the body.
If it exceeds 10, skeletal crippling will occur," Birhanu noted.
As to the possible remedies, the expert recommended that as flourosis is a critical water problem, proper water management in potentially affected areas will significantly reduce the risk.
But he said it required a good knowledge of its sources and distribution and alternative measure and /or a means of adequate reduction.
"In areas where alternative water sources are not readily available, water treatment is the only option to control flourosis though it is expensive," Dr Birhanu said.
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