Sex dating in cego texas Free no registration cyber sex chat one on one

Unlike most others who had noticed this mottling, Mc Kay was intrigued by it and, over the next three decades, he pursued its origins. A range of levels of fluoride led to the severe mottling observed by Mc Kay and others.

He noticed that, whereas people who had lived in a particular community from birth had stained teeth, newcomers to the district did not. Severe mottling was widespread at five parts per million (ppm) and above, but less common at lower concentration.5 Investigators looked to see whether there was a concentration that avoided most mottling while providing the benefits of reduced tooth decay.

Fluoride would be added to bring the concentration to about 1.0 ppm.

The colors ranged from white, yellow, and brown to black. Mc Kay had long observed that mottled teeth, although unsightly, seemed to be more resistant to decay.

In serious cases, there was also pitting of the enamel. Discovery of the fluoride connection finally stimulated the United States Public Health Service (USPHS) to investigate the issue. Trendley Dean, USPHS scientists (mainly dentists) carried out surveys of decay in towns with different fluoride levels and also carried out experiments with animals.

Studying the controversy 106 The fluoridation controversy: which side is science on?

“Fluoridation of Water,” a special report written by associate editor Bette Hileman,1 surveyed the arguments both for and against the measure.

Not surprisingly, opponents of fluoridation were delighted with the article; supporters were dismayed.

More significantly, many correspondents congratulated Bette Hileman and Chemical & Engineering News for raising both sides of the issue for public discussion.A BRIEF HISTORY The use of fluoride to prevent tooth decay was promoted by various individuals in Europe in the 1800s.4 But the key events on the road to fluoridation occurred later and in the United States.Frederick Mc Kay, a dentist, first noticed staining of teeth in his Colorado patients in 1901. Smith in Arizona were able to produce mottling in the teeth of rats by feeding them fluoride. Velu reported the fluoride-mottling link based on work in Morocco and Tunisia. Gay Antonopoulos obtained copies of many publications for me through interlibrary loans. by Edward Groth III 122 Appendix: Fluoridation around the world 137 Acknowledgments Albert Burgstahler, Edith Waldbott, and many others (too numerous to mention) plied me with valuable information through correspondence.Many others were more cautious, including national health administrators and USPHS scientists who were still studying the dental effects of fluoride.

Tags: , ,