Abstract
The purpose of this preliminary investigation was to check some safety aspects in the increased intake of fluorides which may become current in association with the use of fluoride additions to sugar products for prevention of dental caries. A total of 300 men from 4 Finnish rural districts supplied blood samples and samples of their households' drinking water (deriving mainly from wells) and answered questionnaires including questions on circulatory diseases diagnosed by a physician. There was a 50-fold difference between the mean water fluoride concentrations in the extreme districts (from 0.05 to 2.57 ppm). The water magnesium varied parallelly with the fluoride, but there was only a two-fold difference between the means of the extreme districts. A high mean of serum potassium was found in the district showing the lowest means of water fluoride and magnesium. A highly significant negative correlation was found between serum potassium and water fluoride (152 samples of blood and water from 3 districts). The percentage of men with heart and other circulatory diseases was lowest in the district showing the highest water fluoride and magnesium concentrations and highest in the district with the lowest averages for these water elements. Serum triglycerides were elevated in the smokers.