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Uranium isotopes in well water samples as drinking sources in some settlements around the Semipalatinsk Nuclear Test Site, Kazakhstan

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Well water used for drinking in ten settlements around the former Soviet nuclear test site in Kazakhstan was analyzed for uranium isotopes by alpha-particle spectrometry. Uranium-238 varied about one hundredfold between wells, and some wells in four settlements were at or above the World Health Organization proposed guideline the authors cite. Isotope ratios pointed to natural uranium from rock weathering rather than fallout from nuclear explosions.

Key numbers

  • Uranium-238 in well water: 3.6 to 356 mBq/L, equal to 0.3 to 28.7 µg/L (abstract, p. 309; Table 2).
  • Wells in Dolon, Tailan, Sarzhal and Karaul were comparable to or above the WHO proposed guideline of 15 µg/L cited by the authors (p. 311).
  • Irtysh River water: 31 to 37 mBq/L, equal to 2.5 to 3.0 µg/L (p. 311).
  • Uranium-234 to uranium-238 activity ratios 1.1 to 7.9, mostly 1.5 to 3; uranium-235 to uranium-238 activity ratio about 0.046, consistent with natural uranium (abstract, p. 309).
  • Literature freshwater range quoted by the authors: 0.002 to 5 µg/L, median 0.4 µg/L (p. 311).
  • Annual effective dose to adults drinking 2 L/day: 1.0 to 18.7 µSv/y, below the 100 µSv/y reference value the authors cite (Table 3, p. 314).
  • Detection limit about 0.2 mBq of uranium-238 per sample (p. 311).

Methods (brief)

Thirty-five unfiltered well-water samples were acidified, spiked with a uranium-232 yield tracer, separated by anion exchange, electroplated and counted by alpha-particle spectrometry. Major ions were measured by ion chromatography. Doses used settlement geometric means and ICRP ingestion dose coefficients.

Evidence fitness

Supports statements about uranium concentrations in drinking well water in a semiarid region and about the natural origin of that uranium. It addresses radiological dose only; it does not measure kidney or other chemical-toxicity outcomes, and it does not cover food.

Limitations

Small number of wells per settlement, several settlements with a single sample, no health outcome data, and a guideline value taken from an older WHO edition.

Update history

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