Health effects of inorganic drinking water constituents, including hardness, iodide, and fluoride

The influence of drinking water quality on mortality and morbidity of various diseases especially to those of the cardiovascular system has been studied for more than 20 years. In view of the large number of epidemiological studies the results and the opinions on the pathogenicity of the “water factor”; vary considerably. Frequently, the influence of water hardness, certain minerals or heavy metals contained in drinking water on morbidity and mortality is placed in doubt. Applying the same methodological criteria, all large‐scale studies carried out in Japan, the U.S.A., England, Canada, Sweden, and Finland have shown that there are statistical interrelationships between the degree of regional mortality due to cardiovascular diseases and certain ingredients of the drinking water in the same regions. However these interrelationships appear to be fortuitous. In some studies, they refer water hardness; in others, to calcium or magnesium and to a varying spectrum of other ions, heavy metals, and trace elements. Moreover, it was frequently found that such relationships only existed in certain age groups or were restricted to the male or female sex. These interrelationships were found to apply not only to the mortality due to cardiovascular diseases but sometimes also to the total mortality and further causes of death. Also, with respect to other substances contained in drinking water, valid, repeatedly confirmed interrelationships between them and certain diseases are not known. The concepts and methods of investigation used so far do not lend themselves to reveal the existence of one or several “water factors”;. Several reasons are given in the text. While in the case of cardiovascular diseases a significant influence of drinking water could neither be found nor confirmed, there is another disease associated with it which could be confirmed. It is a long established fact that everywhere in the world the occurrence of endemic goiter shows a preference for certain geographic areas. Concentrations of iodide between less than 0.2 and 17.8 g/l iodide were observed in 108 drinking water samples in different localities of the Federal Republic of Germany. A coincidence with the areas where goiter is known to be endemic is indicated. Fluoride means another drinking water constituent that is of importance for a consideration of health aspects of the population. From the extremely large number of publications on this subject, it is shown how close together positive and negative effects of the fluoride content of drinking water may be. Also the content of nitrate, varying over a wide range in the drinking water, will effect human health: high concentrations presents a health risk to babies (methemoglobinemia). Also, nitrate in drinking water may contribute to the formation of carcinogenic compounds in man.