Date of Award
Master of Science (MS)
The recent discovery that even very small concentrations of fluorides in drinking waters are sufficient to cause the serious dental dystrophy commonly known as mottled enamel, has around widespread interest and concern. Federal and State surveys have been conducted to determine the geographical distribution of the malady, and the fluoride contents of water supplies.
County dental surveys, conducted by the United States Public Health Department with the cooperation of local dentists, have located the regions throughout the country where mottled enamel is endemic and among these localities is an area in southeastern North Dakota and adjacent territory in South Dakota and Minnesota where domestic water supplies are obtained almost exclusively from the artesian wells of the Dakota Sandstone formation. In the district the dental lesions have found to be especially severe.
During the past two years the writer has assisted Professor G. A. Abbott, of the University, in making a comprehensive survey of the fluoride contents of the deeper ground waters of the State with special attention to the artesian waters of the Dakota Sandstone basin. This fluoride survey was conducted in cooperation with the State Geological Survey, first, under provisions of the Federal Emergency Relief Administration and, later, with the assistance of a WPA project which is still in progress. A field survey was made by Professor Abbott in person, beginning with the counties where mottled enamel had been reported to be most severe, and later the study was extended to include practically all of the Dakota Sandstone basin in which artesian wells are found. Dentists, physicians, school administrators, well drillers, farmers, and other citizens, were interviewed, conditions were studied and numerous representative water samples were collected and returned to the University chemical laboratory to complete analysis. With the assistance of a specially trained competent staff these waters were then analyzed, not merely for fluorides, but for complete mineral contents, following the standards of precision of the United States Geological Survey. The writer served as assistant chemist in the FERA project, and as Supervisor of the WPA project under the direction of Professor Abbott.
The results obtained in the study of the artesian waters are interesting and surprising in that the distribution of fluorides was found to follow well defined areas or zones which could be mapped with regular contour lines enclosing the areas of different fluoride concentrations, ranging from about 3 parts per million of fluoride in the outermost zone, through successive concentric areas of increasing values, finally converging to a small district in the vicinity of Lidgerwood where the maximum value of 9.9 per million was found.
The correlation of the analytical results with the data obtained from the dental surveys was found to be complete and convincing. In every locality where the dental lesions were pronounced, the drinking waters contained notable amounts of fluorides; while in districts where flouride-free waters are used, mottled enamel was found only among those who have moved into these districts from localities where the artesian waters are used for domestic purposes. The degree of severity of the dental lesions was found to follow the contours of the fluoride map.
The recognition of these conditions has created an insistent demand for practical methods of fluoride removal, not only for use with municipal supplies, but especially for individual domestic supply in those regions where artesian water is the only available supply. Although considerable research on this problem is in progress, no entirely satisfactory method has been developed.
West, Phillip W., "The sorption of fluoride ion with special reference to fluoride removal from potable waters" (1936). Theses and Dissertations. 319.