RADIUM-226-CONTAMINATED DRINKING-WATER - HYPOTHESIS ON AN EXPOSURE PATHWAY IN A POPULATION WITH ELEVATED CHILDHOOD LEUKEMIA

A recent epidemiological survey on childhood malignant disease in the region of Ellweiler, Rheinland-Pfalz, Germany, revealed a significantl y increased incidence of childhood leukemia, but observed incidences o f lymphoma and solid tumors were normal. Established risk factors such as individual exposure to chemicals as well as hereditary genetic dis orders were ruled out in interviews with the patients or their familie s. The general population in the region, however, is subjected to cons iderable doses of ionizing radiation due to high levels of external ga mma radiation and high activities of indoor radon. Radiation-specific chromosome aberrations were found in one of two healthy siblings and o ne father of leukemia patients as well as in any of three probands liv ing in houses with high indoor radon activities. Radon and natural gam ma radiation, however, cannot explain the geographical pattern of the cases. Four out of seven cases were observed in two particular village s near a uranium processing plant. The drinking water of these village s partly came from a small river that was contaminated with radium-226 washed out from the dumps of the uranium plant. Only sparse measureme nts of Ra-226 are available, but derived red bone marrow doses for chi ldren in the two villages obtained from a simple radio-ecological mode l show the significance of the drinking water pathway. Prenatal Ra-226 exposure of fetuses due to placental transfer and accumulation may ha ve led to significant doses and may explain the excess cases of childh ood leukemia in the region even in quantitative terms.