| dc.description.abstract | Synopsis of the thesis titled Studies on Fluorine and Fluorine Poisoning, with a chapter each on (i) constitution of bone salt and tricalcium phosphate, and (ii) mechanism of calcification, submitted by T. K. Wadhwani for the Fellowship of the Indian Institute of Science.
(i)
The existing data on the biochemistry of fluorine poisoning have been reviewed, and suggestions have been made for the study of the nature of fluorosis, the methods for the mitigation of the accumulated effects of fluorine in humans and animals, and for the biological determination of the sub toxic level of fluorine intake.
(ii)
Methods have been studied and devised for the micro and macro determination of fluorine.
(iii)
The removal of fluorine by calcium oxide, sulphate, carbonate, rock phosphate, fluor apatite, chlor apatite, raw bone meal, purified bone meal, and calcium phosphate has been studied. It has been shown that:
(a) fluorine is not removed by rock phosphate, fluor apatite, and chlor apatite;
(b) in small concentrations fluorine is not removed by calcium carbonate, but in large concentrations calcium carbonate removes fluorine by the mechanism of ionic adsorption involving the exchange of fluoride with the CO ² of calcium carbonate; the percentage of calcium and carbonate in a molecule of calcium carbonate has been found to be in agreement with the formula CaCO ;
(c) calcium oxide and calcium sulphate remove fluorine from its aqueous solution by the mechanism of double decomposition-the solubility of the precipitated calcium fluoride is the limiting factor for the complete removal of fluorine;
(d) fluorine is removed by raw bone meal, purified bone meal, and calcium phosphate by the mechanism of ionic adsorption involving the exchange of fluoride with the already adsorbed hydroxide and phosphate.
Methods for the removal of fluorine from drinking water have been discussed.
(iv)
On the basis of the data regarding the mechanism of fluorine removal by bone salt and calcium phosphate, the constitution of bone salt and calcium phosphate has been elucidated. It has been suggested that in alkaline solutions, including plasma, the precipitate that first forms is CaHPO , which immediately after formation undergoes an intramolecular reaction resulting in the formation of a precipitate having the crystal lattice of an apatite structure. It has been further suggested that, by virtue of the nature of the forces responsible for the placement of components in the crystal lattice, bone salt and calcium phosphate, when brought into contact with solutions of ions-either their own or foreign-take up some ions from the liquid phase and release some ions from the solid phase in accordance with the laws of adsorption.
(v)
In the light of this concept of the constitution of bone salt and calcium phosphate, the properties of these salts in vitro, the behaviour of bone salt in vivo, and the mechanisms of primary and secondary calcification have been explained.
(vi)
The effect of fluorine on the metabolism-exogenous as well as endogenous-of nitrogen, calcium, and phosphorus has been studied. It has been shown that fluorine interferes with the exogenous and endogenous metabolism of nitrogen, calcium, and phosphorus by decreasing the primary and secondary absorption of these elements by lowering the absorptive ability of the intestinal cells, and by increasing the urinary excretion of exogenous and endogenous nitrogen and phosphorus. Apart from the effect of fluorine on the absorption of these elements, fluorine in the system primarily interferes with the metabolism of nitrogen and phosphorus, causing increased urinary excretion of these elements. Disturbance in the metabolism of calcium is confined to its decreased absorption from the intestine, resulting in reduced availability to the system.
Methods have been indicated for the biological determination of the sub toxic level of fluorine intake. The protective action of high calcium and high protein diets in fluorine poisoning has been explained.
(vii)
Studies have been carried out on the effect of fluorine on the composition of bones of rats and monkeys under different dietetic and physiological conditions. It has been shown that the effect of fluorine on the bones is, firstly, due to its interference with the metabolism of nitrogen, calcium, and phosphorus, and secondly, due to its direct effect on the bone cells. In the light of the data presented, the process of bone formation has been differentiated into two mechanisms:
one responsible for the formation of the organic intracellular matrix, and
the second responsible for the deposition of lime salts.
Fluorine interferes, even in low concentrations, primarily with the normal functioning of the first mechanism and causes inadequate formation of the supporting collagen, as evidenced by the lower nitrogen percentage in the bones.
(viii)
Finally, methods have been shown for the successful mitigation of the toxicity of ingested fluorine in experimental monkeys as well as in humans suffering from endemic fluorosis. | |
