Table 2 : The average fluoride concentrations in the well water of different provinces of Sri Lanka Province Average Fluoride
Fluorine, the most reactive and electro-negative halogen on the earth, is an element that virtually never occurs naturally in its free, gaseous form In the form of fluorides, however, it is one of the most plentiful and wide spread of elements, standing seventeenth in order of abundance in the earth's crust. Fluorides occur in water, soil, rocks, dusts and the atmosphere. It is also present in most foods, many plants and virtually in all animal tissues. Fluoride is considered as an essential element for the human body for promoting growth of healthy bone and teeth. Although every food stuff contains at least a trace of fluoride, the total intake of fluoride from food is relatively small, and most of it is ingested through drinking water.
Geochemistry, genesis, and health implications of fluoriferous groundwaters in the upper regions of Ghana
Abstract The most appropriate and widely used source of drinking water for the populations of the upper regions of Ghana is groundwater. In general, groundwater quality is acceptable except for some parts of the Bolgatanga and Bongo Districts, where there are occurrences of elevated levels of natural groundwater fluoride. Concentrations of groundwater fluoride in excess of the World Health Organization (WHO) maximum guideline value (1.5 mg/l) in the Bongo area have been known since 1978. However, the effect of fluoride on people ingesting the water did not receive public and medical attention until October 1993, when health personnel were asked to investigate the cause of stained teeth in school children. The investigation established that 62% of the total population of school children in the Bongo area had dental fluorosis. Against this background, a study was initiated to understand the geochemistry, genesis, and distribution of fluoride in relation to the geology of the area. Groundwater fluoride in the upper regions ranges from 0.11 to 4.60 ppm, with the highest concentrations associated with the fluorine-enriched Bongo coarse-grained hornblende granite and syenite suite. The source of groundwater fluoride within the Bongo granitoids is dissolution of the mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products. Applying the WHO recommended guideline values for fluoride in drinking water reveals that 49% of wells in the area deliver water below the optimum level of 0.5 mg/l F–; these populations are thus prone to dental caries. Twenty-eight percent of the wells fall within the optimum interval for good dental health (0.5–1.5 mg/l F–). Twenty-three percent of the wells have concentrations above the recommended maximum guideline limit of 1.5 mg/l F–; this population is susceptible to dental and possibly skeletal fluorosis. Climatic conditions of the area suggest that the individual water consumption is in the order of 3 to 4 l which is higher than the WHO estimate of 2 l/adult/day. In addition, dietary intake for the upper region population is probably higher than WHO baseline values (0.2–0.5 mg/day). This implies that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected. Geochemical symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions, but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education programs in the region. By casting fluoride data into contoured 'geochemical health-risk maps' using intake interval guidelines more closely aligned to regional climatic and dietary conditions, health officals can better judge the impacts (regional and population based) of fluoride on segments of the population, such as various sex and age groups.
Prevalence of endemic fluorosis with gastro-intestinal manifestations in people living in some North-Indian villages
Numerous reports on epidemiological surveys of skeletal and dental fluorosis exist, but information is quite limited on non-skeletal manifestations of fluoride toxicity. The present study was conducted to assess the prevalence and severity of non-skeletal manifestations, especially gastrointestinal disturbances, in an area of skeletal and dental fluorosis. The subjects, numbering 1958 inhabitants belonging to 489 families residing in four endemic villages of Faridabad District of Haryana State, were interviewed on health complaints. The information was recorded in a precoded questionnaire. Every drinking water source was analysed for fluoride content. This led to the identification of "safe" (fluoride 1 ppm or less) and "contaminated" (fluoride above 1 ppm) sources of water. Results revealed that among the subjects were people affected with: 1) Dental fluorosis (58%), 2) Skeletal fluorosis (27%), 3) Non-skeletal manifestations (41%) and 4) Gastrointestinal complaints (26%). Those affected were consuming water contaminated with fluoride ranging from 0.25-8.00 ppm. Among the total of 78 sources of water, 20 were "safe" while the remaining 58 were more contaminated with fluoride from natural sources. It is concluded that in an endemic zone, where the inhabitants are consuming water of high floride content, the occurence of gastrointestinal complaints; viz., loss of appetite, nausea, abdominal pain, flatulence, constipation and intermittant diarrhoea - is one of the early warning signs of flouride toxicity and fluorosis. When water with negligible amounts of flouride (safe water) is provided, the complaints disappear within a fortnight.