The etiology of Balkan endemic nephropathy: still more questions than answers.

Balkan endemic nephropathy (BEN) has attracted increasing attention as a possible environmental disease, and a significant amount of research from complementary scientific fields has been dedicated to its etiology. There are two actual competing theories attempting to explain the cause of this kidney disease: 1) the mycotoxin hypothesis, which considers that BEN is produced by ochratoxin A ingested intermittently in small amounts by the individuals in the endemic regions, and 2) the Pliocene lignite hypothesis, which proposes that the disease is caused by long-term exposure to polycyclic aromatic hydrocarbons and other toxic organic compounds leaching into the well drinking water from low rank coals underlying or proximal to the endemic settlements. We outline the current developments and future prospects in the study of BEN and differentiate possible factors and cofactors in disease etiology.

Relationship between weathered coal deposits and the etiology of Balkan endemic nephropathy.

Field studies in epidemiology and environmental geochemistry in areas in Yugoslavia containing villages with a high incidence of Balkan endemic nephropathy (BEN), indicate a possible relationship between the presence of low-rank coal deposits and the etiology of BEN. Preliminary results from qualitative chemical analyses of drinking water from shallow farm wells indicate the presence of soluble polar aromatic and polynuclear aromatic hydrocarbons. These compounds may be derived from weathering of low-rank coals occurring in the vicinity of the endemic villages. All of the endemic villages are in alluvial valleys of tributaries to the Danube River. All except one of the clusters of endemic villages are located in the vicinity of known Pliocene age coals. Detailed sampling of the drinking waters and the nearby coals are being undertaken to identify a possible etiologic factor.

Chemical qualities of water that contribute to human health in a positive way.

The emphasis on harmful substances that may occur in potable waters has almost obscured the fact that important beneficial constituents are commonly present. The chemical substances in water that make positive contributions to human health act mainly in two ways: (i) nutritionally, by supplying essential macro and micro elements that the diet (excluding water) may not provide in adequate amounts (for example, Mg, I and Zn); and (ii) by providing macro and micro elements that inhibit the absorbtion and/or effects of toxic elements such as Hg, Pb and Cd. Specific examples of these beneficial effects will be given, also examples of harmful effects on health that may result from excessive intake of these ordinarily beneficial elements. Because concentrations of the essential macro and micro elements that occur in natural, potable waters vary greatly, depending upon their source, geographic considerations are very important in any studies attempting to relate water quality to health. In this context, the inverse relationship between hard water and cardiovascular disease will be discussed. Specific data relating hardness and Mg and Ca content of potable waters to specific geographic regions of the U.S.A. will be presented. These data show a strong positive correlation between low Mg content and decreased longevity, and between high Ca and Mg content and increased longevity. In the regions considered, increased longevity correlates strongly with decreased cardiovascular mortality, and the decreased longevity with increased cardiovascular mortality.