CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
Fluoride is one of the very few chemicals that have been shown to cause significant effects in people through drinking-water. Fluoride has beneficial effects on teeth at low concentrations in drinking-water, but excessive exposure to fluoride in drinking-water, or in combination with exposure to fluoride from other sources, can give rise to a number of adverse effects. These range from mild dental fluorosis to crippling skeletal fluorosis as the level and period of exposure increases. Crippling skeletal fluorosis is a significant cause of morbidity in a number of regions of the world (J. Fawell, K. Bailey, J. Chilton, E. Dahi, L. Fewtrell and Y. Magara 2006).      Fluoride is known to occur at elevated concentrations in a number of parts of the world and in such circumstances can have, and often has, a significant adverse impact on public health and well-being (J. Fawell, K. Bailey, J. Chilton, E. Dahi, L. Fewtrell and Y. Magara 2006).     There is now a continuing process of updating the (GDWQ) Guideline for Drinking Water Quality, through which it was concluded that there was a need for a monograph on fluoride in drinking-water that would be useful to a wide range of individuals, including health workers and sanitary engineers who may require a broad introduction to the subject, but would still provide more detailed guidance in some specific areas. Such a monograph could provide an appropriate introduction and background information, and indicate where other more detailed information could be obtained. The primary focus of the monograph is  the prevention of adverse effects from excessive levels of fluoride in drinking-water.   Fluoride is found in all natural waters at some concentration. Seawater typically contains about 1mg l–1 while rivers and lakes generally exhibit concentrations of less than 0.5 mg l–1. In groundwater, however, low or high concentrations of fluoride can occur, depending on the nature of the rocks and the occurrence of fluoride-bearing minerals. Concentrations in water are limited by fluorite solubility, so that in the presence of 40 mg l–1 calcium it should be limited to 3.1 mg l–1(Hem, 1989). It is the absence of calcium in solution which allows higher concentrations to be stable (Edmunds and Smedley, 1996). Iree town which is the focus of this project work has a very high tendency for the presence of fluoride in its ground water because of the geological nature of the area. Iree is a town surrounded by different rocks and the presence of this rock naturally leads to the presence of fluoride in all the well water in Iree metropolis. The problem that necessitated this project include dental fluorosis and skeletal deformation in some people living in Iree metropolis.           This project is to determine the effect and implication of fluoride on drinking well water in some areas in Iree community of Osun state, Nigeria.