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

Background: Polonium-210 ((210)Po) 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 (210)Po are common in sediments, and segments of the public may be chronically exposed to low levels of (210)Po 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 (210)Po and identified the need for future research. Methods: Potential linkages between environmental exposure to (210)Po and human health effects were identified in a literature review. Discussion: (210)Po accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate (210)Po, the ovary may be the critical organ in determining the lowest injurious dose for (210)Po. (210)Po also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to (210)Po 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. (210)Po is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of (210)Po. Conclusions: Much of the important biological and toxicological research on (210)Po is more than four decades old. New research is needed to evaluate environmental exposure to (210)Po and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary.