Occurrence of 210Po and Biological Effects of Low-Level Exposure: The Need for Research

BACKGROUND: Polonium-210 (Po-210) concentrations that exceed 1 Bq/L in drinking-water supplies have been reported from four widely separated U.S. states where exposure to it went unnoticed for decades. The radionuclide grandparents of Po-210 are common in sediments, and segments of the public may be chronically exposed to low levels of Po-210 in drinking water or in food products from animals raised in contaminated areas. OBJECTIVES: We summarized information on the environmental behavior, biokinetics, and toxicology of Po-210 and identified the need for future research. METHODS: Potential linkages between environmental exposure to Po-210 and human health effects were identified in a literature review. DISCUSSION: Po-210 accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate Po-210, the ovary may be the critical organ in determining the lowest injurious dose for Po-210. Po-210 also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to Po-210 may have subtle, long-term biological effects because of its tropism towards reproductive and embryonic and fetal tissues where exposure to a single alpha particle may kill or damage critical cells. Po-210 is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of Po-210. CONCLUSIONS: Much of the important biological and toxicological research on Po-210 is more than four decades old. New research is needed to evaluate environmental exposure to Po-210 and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary.