title: Occurrence of ²¹⁰Po 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.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Environmental Sciences Graduate Program, University of Nevada-Reno, P.O. Box 1025, Carson City, NV 89702, USA. rlseiler@juno.com
authors.forename: Ralph L
authors.initials: RL
authors.lastname: Seiler
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Wiemels
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004781:Environmental Exposure; D006801:Humans; D011059:Polonium / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity*; D011834:Radiation Monitoring; D014018:Tissue Distribution
chemical_list: D011059:Polonium