Sulfur-35 is a commonly used radionuclide with a half-life of 87.4 days, emitting only beta particles with a maximum energy of 0.167 MeV (Million Electron Volts) and an average energy of 0.049 MeV. The beta particles from S-35 travel a maximum of 24 cm. in air.
Contamination on the skin will not likely cause a significant dose to the dead layer of skin, however, it could lead to the internal absorption of S-35 if there are cuts in the skin. The Annual Limit on Uptake (ALI) for S-35 for ingestion set by the NRC and NYS Health Department State Sanitary Code, Chapter I, Part 16 is 1E+4 uCi (3.7E+5 kBq).
Another concern involving S-35 is the possibility of radioactive gas releases by self-decomposition during certain labeling experiments. This has been documented with [S-35]-Met/Cys used in labeling proteins regardless of the manufacturer or grade of label. Typical procedures have the potential of releasing significant amounts of radioactive gas that could contaminate all components of your continuous flow CO2 incubator. Use of this compound in a fume hood (approved and labeled for radioactive use) or in a specially designed containment system (i.e.Billups-Rothenberg Hot Box System) will reduce the possibility of lab contamination by keeping levels ALARA (As Low As Reasonably Achievable). Contact EH&S for further information.
The following equipment and supplies must be available before handling S-35:
Glass and plastic are the best shields for beta particles from S-35.
If the following safety precautions are used when handling S-35, personnel radiation exposure will be as low as reasonably achievable.
Any questions about these procedures? Call EH&S at
A tiny drop of contamination from S-35 can be easily detected with a wipe test from a Liquid Scintillation Counter. A Gieger Counter has a low effeciency for S-35, but high activities can be detected.