[Balkan nephropathy and urothelial cancer. Well water pollution and current questions on pathogenesis and carcinogenesis].

In the autopsied inhabitants who died from unrelated reasons in the villages-foci of Balkan Nephropathy (BN) the characteristic histologic changes of the initial phase of BN were found as well as the striking difference in the weight of the kidneys. The weight of a kidney amounting to 180 grams was noted. The continual, severe environmental exposure to polluted drinking water by erosive toxic silica accounts for the excessive silica accumulation in the kidney and its overhydration. Silica has an affinity for water molecules absorbating them on its surface, the absorption of water coats round the accumulations of polymerized silica being formed by several water molecular layers. The increased kidney weight, however, may be regarded as a very rare one and is possible in the initial phase of disease. In most cases the dehydrating, atrophic and necrotic activity of toxic silica characterizes all developmental phases of BN leading to a loss of both fluid and mass of the kidney. In the rainy season fresh submironic suspension of toxic silicate particles is the most toxic for human kidneys. When deposited in drinking waters the larger ones encounter conditions suitable for further solution humus matter and CO2 and the drinking water becomes toxic for human kidneys in the dry season as well. In the course of time the metamorphic process of silica particles being completed these drinking waters become slightly toxic or not toxic at all. In relation to the inactive silica the other component of magmatic silicate rocks heavy, tumorogenic metals preserve the reactivity for a longer time and are responsible for the urothelial carcino-genesis unfollowed by chronic kidney insufficiency in the areas where BN is endemic.