Radionuclide Fact Sheet
SULFUR - 35
Symbol: 35S
States/Forms: Soluble, except gaseous
Physical Characteristics
- Radioactive Half Life (T½): 87 days
- Decay Type: Beta- (ß-)
- Maximum Energy Emission: 0.167 MeV
- Maximum Range in Air: 26 cm
- Maximum Range in Water/Tissue: 0.04 cm
- Maximum Range in Plexiglas or Lucite: 0.025 cm
Hazard Category
- A Level (High Hazard): >1 Ci
- B Level (Moderate Hazard): >20 mCi to 1 Ci
- C Level (Low Hazard): 0.1 mCi to 20 mCi
Radiological Characteristics
- ~15% of beta particle energy transmitted through dead layer of skin.
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Critical organs: Testes
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Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).
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Internal exposure and contamination: Primary radiological concerns with 35S.
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External exposure: Minimal concern for 35S.
Dosimetry
- Film badges and dosimeter rings are not appropriate for monitoring 35S exposure.
Bioassay Requirements
- Urinalysis may be required after spills or incidents of contamination.
External Radiation Hazards and Shielding
- There is minimal external hazard with 35S, i.e. the glass vial containing the 35S provides sufficient shielding from the beta particles, however lucite or plexiglas may be used as shielding. If the skin is uniformly contaminated with 35S, 1 microcurie/cm2 (μCi/cm2) will deliver a dose of 1200 miilirads per hour (mrad/hr) to the basal skin cells.
Hazards if Internally Deposited
ALI (Annual Limit of Intake):
- 1 x 104μCi – by ingestion
- 6 x 10-6μCi – by inhalation
DAC (Derived Air Concentration):
- 2 x 10 -8 µCi/mL
Survey Instrumentation
- A thin window Geiger-Muller detector can be used to detect 35S, however the survey meter probe must be within a very close range (< 1 inch).
- A Geiger-Muller survey detector with a pancake/frisker probe has a very low counting efficiency for 35S (~4%).
- Liquid scintillation counters should be used to detect removable surface 35S contamination using smears or swabs.
Problems and Precautions
- Lab coats and protective gloves should always be worn when working with 35S to keep skin free from contamination, and gloves should be changed often.
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All waste in a 35S work area is considered to be contaminated. Work areas should be kept free of unnecessary items.
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35S compounds are often volatile or produce volatile products. 35S should be opened and handled in a fume hood.
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Activated charcoal should be used when incubating samples.
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Waste should be segregated to those with half-lives from 65 days to less than 90 days.