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

Abstract

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

Radionuclide exposure in animals and the public health implications

“…Further studies in animals revealed that 210 Po accumulates in the reproductive and hemopoietic systems and probably transfers from the mother to the embryo/ fetus, causing critical cells to suffer damage as a result of its alpha particles (41). This fetal exposure could cause failure of implantation, fetal miscarriage, or major malfunctions (42).…”

“…For instance, 210 Po, an alpha-particle emitter, is one of the most toxic substances known because of its intense radioactivity and is therefore classified as a Group I human carcinogen (42,52). Concentrations as low as 1 µg have an activity of 1.66 × 10 8 Bq, and acute lethal doses may cause severe damage to the bone marrow, kidneys, spleen, digestive tract, and reproductive system (40,41). The preference therefore of important radionuclides for certain organs/ tissues for bioaccumulation may serve as an informational tool in making dietary choices, in which case, consumption of organs that tend to accumulate radionuclides may be avoided.…”

Radioactivity in drinking water supplies in Western Australia

“…However, there is little data on Po-210 (ARPANSA, 2008: Seiler andWeimels, 2012) and on the effects of human exposure to Po-210 (Seiler and Weimels, 2012). Po-210 concentrations in groundwater are generally low due to geochemistry and microbial processes that mobilise only small percentages of the Po-210 present.…”

“…Po-210 concentrations in groundwater are generally low due to geochemistry and microbial processes that mobilise only small percentages of the Po-210 present. However, these concentrations are sufficient to contribute significant doses and exceed safe levels in DW (ARPANSA, 2008: Seiler andWeimels, 2012). Seiler and Weimels (2012) have discovered that Po-210 is a possible cause of leukaemia as it accumulates in the reproductive organs and furthermore that most childhood leukaemias originate before birth and are passed on from the mother to child.…”

“…However, these concentrations are sufficient to contribute significant doses and exceed safe levels in DW (ARPANSA, 2008: Seiler andWeimels, 2012). Seiler and Weimels (2012) have discovered that Po-210 is a possible cause of leukaemia as it accumulates in the reproductive organs and furthermore that most childhood leukaemias originate before birth and are passed on from the mother to child. The authors are of the view that the lack of data on Po-210 is due to the fact that it has not been looked for very much in the past.…”