Selenium-Accumulating Wildflowers in South Dakota; Evaluating Health Risks from Naturally-Occurring Uranium at the Former Badlands Bombing Range by Dr. Mike Lambert

1
Selenium-Accumulating Wildflowers in South
Dakota Evaluating Health Risks from
Naturally-Occurring Uranium at the Former
Badlands Bombing Range byDr. Mike Lambert

• TOSNAC Presentation to Restoration Advisory Board
• August 27, 1998

2
Selenium

• Selenium is an essential nutrient for all animals
  in trace quantities, but is toxic in large
  amounts.
• Selenosis (alkali disease) happens when
  livestock drink water or eat plants with
  excessive selenium.
• Selenium is not used in bombs or bomb casings
  the selenium found at the BBR is from natural
  sources.

3
Selenium (continued)

• Selenium in local bedrock formations can be as
  high as 23.1 ppm.
• EPA RBCs for selenium in soil are 390 ppm for
  residential sites, and 10,000 ppm for industrial
  (and agricultural) sites.
• The highest concentration of selenium in
  groundwater at the nearby Former Black Hills Army
  Depot is 0.34 ppm. The EPA maximum level for
  drinking water is 0.05 ppm.

4
Selenium (continued)

• Selenium can commonly be as high as 1 ppm in some
  plants, and can be as high as 1,000 to 15,000 ppm
  in a few plants.
• Selenium over 2 to 5 ppm in forage is potentially
  hazardous to domestic animals.
• Some plants in South Dakota have plants that can
  accumulate over 50 ppm selenium.

5
Uranium at the BBR

• Maximum uranium concentration in soil in southern
  South Dakota is 11 ppm.
• U in Soil (ppm) X 10-6 X Dust Action Level
  (mg/m3) U concen. as dust in air (mg/m3).
• If BBR soil created enough dust to create a
  health nuisance, uranium in that dust would still
  be 1,000 times below the level at which breathing
  the metal would be a health hazard.
• However, inhalation as dust may not be as
  important for uranium as for other metals.

6
Uranium at the BBR (Cont.)

• Another way to look at the possible health risk
  posed by natural uranium is by comparing the
  level of uranium in BBR soil to the limits set by
  the EPA in their Region III RBC Table for
  residential and industrial sites.
• That table sets a limit for uranium in soil at
  residential sites of 230 ppm, and at industrial
  (or agricultural sites) of 6,100 ppm. The highest
  level of uranium in soil found in southern South
  Dakota is 11 ppm.

7
Uranium at the BBR (Cont.)

• Even natural uranium is radioactive, and given
  enough time, will break down into other chemical
  elements, including radon.
• Radon is a heavy gas that can cause cancer if it
  accumulates in closed areas, and if people are
  exposed to it over a long time.
• The United States Geological Survey ranks
  southwestern South Dakota as having a moderate
  risk for radon.

8
Summary

• Natural selenium in southwestern South Dakota can
  pose a health problem for livestock because of
  high concentrations in some aquifers, and because
  some local plants (loco weed, goldenweed, and
  princes plume) accumulate high levels of
  selenium.
• Natural uranium does not seem to pose a health
  risk at the Former BBR.