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Spacecraft Water Exposure Guidelines for Selected Contaminants Volume 3 (2008) / Chapter Skim
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Introduction
Pages 1-10

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From page 3...
... requested that the National Research Council (NRC) provide guidance on how to develop water exposure guidelines and subsequently review NASA's development of the exposure guidelines for specific chemicals.
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From page 4...
... Other sources of chemical contaminants include mechanical leaks, microbial metabolites, payload chemicals, biocidal agents added to the water to retard bacterial growth (such as silver and iodine) , fouling of the filtration system, and incomplete processing of the water.
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From page 5...
... Risk Assessment Several risk assessment methods can be used to derive SWEGs. Risk assessments for exposure to noncarcinogenic substances traditionally have been based on the premise that an adverse health effect will not occur below a specific threshold exposure.
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From page 6...
... Special Considerations for NASA When deriving SWEGs, by either the NOAEL/LOAEL or the BMD approach, it is necessary to use exposure conversions and uncertainty factors to adjust for weaknesses or uncertainties about the data. When adequate data are available, exposure conversions that NASA should use include those to adjust for target tissue dose, differences in exposure duration, species differences, and differences in routes of exposure.1 Uncertainty factors should also be used to extrapolate animal exposure data to humans, when human exposure data are unavailable or inadequate; to extrapolate data from subchronic studies to chronic exposure; to account for using BMDL10 instead of BMDL01 (or a LOAEL instead of a NOAEL)
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From page 7...
... As described above, the procedure for developing SWEGs involves identifying toxicity effects relevant to astronauts and calculating exposure concentrations on the basis of those end points. The lowest exposure concentration is selected as the SWEG, because the lowest value would be expected to protect astronauts from manifesting other effects as well.
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From page 8...
... Washington, DC: National Academy Press. NRC (National Research Council)
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From page 9...
... Washington, DC: National Academy Press. NRC (National Research Council)
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Key Terms

  • exposure guidelines
  • water exposure
  • spacecraft exposure
  • airborne contaminants
  • selected airborne

  • uncertainty factors
  • exposure conversions
  • selected contaminants
  • sweg reports
  • human exposure

  • exposure data
  • developing spacecraft
  • guidelines set
  • assessment methods
  • methyl ethyl

  • propylene glycol
  • continuous exposure
  • animal exposure
  • exposure studies
  • ing exposure

  • chronic exposure
  • priate exposure
  • establishing exposure
  • exposure approximates
  • set exposure

  • oral exposure
  • calculate exposure
  • exposure duration
  • exposure levels
  • exposure times


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