Regulation of human plasma fluoride concentration.

of human plasma fluoride concentration. rg6o.-There is a constancy of plasma fluoride content of individuals who use communal water within the range O. 15-2.5 ppm fluoride. With an intake of 5.4 ppm of fluoride in the communal water there is a slight but significant elevation of the plasma concentration. There is no evidence of a marked or prolonged rise of plasma fluoride content following the ingestion of I .o mg fluoride or of a diurnal variation of plasma fluoride content. The mean plasma fluoride concentration of hospitalized patients is not different from that of normal people. The factors relating skeletal fluoride content to small and short-term rises of plasma fluoride concentration are discussed. I NTEREST IN THE METABOLIC TRANSPORT and disposition of fluoride has been heightened as a result of adoption of fluoridation of public water supplies as a means of reducing the dental caries attack rate. Fluoride has a ubiquitous occurrence in the human diet but studies of its metabolism have been mainly those in which large doses have been used. This circumstance is the result of the lack of methods sufficiently precise to permit the accurate determination of fluoride at its normal concentration in tissues and body fluids. A procedure of demonstrated reliability for the determination of fluoride in 3-5 ml of plasma (or serum) has been described (I). This method has now been employed to survey the fluoride content of the blood plasma of residents of five Midwestern communities in which the fluoride content of the communal water varies from o. I to 5.4 ppm. Whole blood fluoride determinations have been reported by other investigators. In one study (2) the whole blood fluoride concentration of residents of two urban populations were found to be 0.014 and 0.040 ppm when the water supplies of the two cities contained respectively 0.06 and 1.36 ppm fluoride. In the study here reported plasma instead of whole blood has been analyzed because of the unequal distribution of fluoride on a volume basis Recei ved for publication November 19, 1959.3go from the Office of the Surgeon General, Department of the Army. between plasma and red cells. Furthermore, plasma is the fluid of physiologic interest since it is a part of the extra-cellular fluid which bathes cells and bone mineral and is the body fluid from which urine is formed. METHODS The communities of residence of the blood donors are identified in table I. …