Fluoride levels in seven commercial phosphate fertilizers (four single superphosphate samples, two diammonium phosphate samples, and one ammonium nitrophosphate sample) were analyzed independently at three laboratories employing the techniques of ion chromatography and ion-selective electrode. The results were consistent for aqueous solutions containing 100?mg?L?1 (ppm) of fertilizer. The average values of fluoride from four different studies varied from 0.140?±?0.006–1.33?±?0.158% (w/w) for the seven fertilizer samples. The [P2O5]/[F] ratios (w/w) were computed for all the seven samples and the values were in the range of 13.79–328.57. By comparing these values with the average [P2O5]/[F] ratio in phosphate rock, it was inferred that 3–75% of fluoride originally present in rock remained in the fertilizers. IR spectral data revealed a small peak at 716?cm?1 – indicative of SiF62? – in the sample containing lowest fluoride which may be on account of fluoride stripping of intermediate phosphoric acid with reactive silica in this case. Considering 15 MMT (million metric tons) of annual consumption of phosphate fertilizers in India, the incremental load of fluoride in agricultural fields was estimated to be 127,650?±?14,550 MTy?1 based on the grand average fluoride content of 0.851?±?0.097% (w/w). While a part of this fluoride would likely get discharged into oceans through run-off, the remainder may persist in the soil, some amount may accumulate in vegetation, and a part might find its way into fresh water bodies, thereby aggravating the fluoride problem in the Country. The problem of non-point source pollution can be reduced by eliminating fluoride at source, and utilizing the recovered fluoride as feedstock. This could, in principle, satisfy the entire requirement of the fluorochemicals industry in India. Environmental costs need to be factored in while making an assessment of the viability of fluoride recovery and reuse in this manner compared to production from virgin sources of fluoride.
Risk of enamel fluorosis in nonfluoridated and optimally fluoridated populations: considerations for the dental professional.
BACKGROUND: Few studies have evaluated the impact of specific fluoride sources on the prevalence of enamel fluorosis in the population. The author conducted research to determine attributable risk percent estimates for mild-to-moderate enamel fluorosis in two populations of middle-school-aged children. METHODS: The author recruited two groups of children 10 to 14
Fluoride intake and urinary excretion in preschool children residing in Koohbanan, Iran, a city with high fluoride water and food.
The amount of fluoride (F) ion excreted in 24-hr urine of preschool children in Koohbanan, Iran, was measured. The total volume of urine over a 24-hr period of 26 healthy 4–5 yr-old children (14 boys and 12 girls with a mean body weight of 16 kg) was collected under carefully
Risk factors associated with fluorosis in a non-fluoridated population in Norway.
In Norway, there is no water fluoridation and little naturally occurring fluoride in drinking water. Fluoride toothpaste is used by 95% of the population and there is a long tradition of fluoride supplement use. The purpose of this study was to record the prevalence and severity of dental fluorosis in
Patterns of fluoride intake from 36 to 72 months of age
OBJECTIVES: This paper reports on estimated daily fluoride intake from water by itself, beverages, selected foods, dentifrice, and dietary supplements, both individually and combined (mg and mg F/kg bw), among 785 children in the Iowa Fluoride Study from 36 to 72 months of age. METHODS: Children were recruited in 1992-95,
A review of fluoride in African groundwater and local remediation methods.
Groundwater is the major source of drinking water supply in the bulk of African urban and rural communities. However, groundwater in some parts of the African countries contains fluoride in concentrations exceeding the 1.5 mg/L permissible limit established by the WHO. No confirmed data are available on the number of people
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