A special study was made of the quantitative excretion of albumin, red blood cells, and casts in 12-hour urine specimens in 12-year-old boys as part of the long-term study of children in the Newburgh-Kingston caries fluorine study. The objective of this study was to determine whether any irritative efIects on the kidneys followed long-term ingestion of fluoridated water, with use of a more refined technique than routine urine analysis, which is performed as part of the annual pediatric examinations in the Newburgh-Kingston study. The findings in a group of 100 boys in Newburgh who had been exposed to fluoridated drinking water for about eight years were compared with the findings in a group of similar size in Kingston, where the drinking water is essentially fluoride-free. The collection and examination of urine specimens followed the Addis method as modified by Lippman. No limitation was placed on the boys’ physical activity prior to collection of the 12-hour specimens.
The mean of the albumin determinations in the Kingston, specimens was 34.1 mg., with a standard deviation of 12.9 mg. The corresponding mean and standard deviation for Newburgh was 29.0 mg. and 13.4 mg. respectively. The average number of red blood cells excreted in the Kingston specimens was 14,700 and in the Newburgh specimens 10,300. In the Kingston group, 60% of the specimens showed a red blood cell count under 20,000 and in the Newburgh group this was true of 78 %. The average number of casts in the Kingston specimens was 2,800 and in the Newburgh specimens 1,900. In the Kingston group, no casts were found in 56% of the specimens, and in the Newburgh group no casts were found in 68% of the specimens.
The differences found in the results from the groups in the two cities tended to favor the Newburgh children. No medical significance can be attributed to any of the differences. This study adds further weight to the mass of evidence already available that points to the safety of water fluoridation as a public health measure for the prevention of dental caries.