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Saturday, October 15, 2011

Working Practices When Using Radioactive Isotopes

What is Radioactivity?

Radioactivity is a very interesting phenomenon in nature. Classical Electromagnetism cannot explain radioactivity. It's a spontaneous and random phenomenon whereby nuclei of certain chemical elements like Uranium, radiate gamma rays (high frequency electromagnetic radiation), beta particles (electrons or positrons) and alpha particles (Helium Nuclei).

By the emission of these particles and radiation, the unstable nucleus gets converted into a stabler nucleus. This is called radioactive decay. In the list of radioactive elements, all the elements which undergo decay are listed. Find more information on radioactivity through the articles, 'what is radioactivity?' and meaning of radioactivity decay.

Types of Radioactive Decay

This decay may occur in any of the following three ways:

  • Alpha Decay: Nucleus emits a helium nuclei (called an Alpha Particle) and gets converted to another nucleus with atomic number lesser by 2 and atomic weight lesser by 4.
  • Beta Decay: Beta decay could be of two types. Either through emission of an electron or positron (the antiparticle of electron). Electron emission causes an increase in the atomic number by 1, while positron emission causes a decrease in the atomic number by 1.
  • Gamma Decay: Gamma decay just changes the energy level of the nucleus.
A radioactive element may have more than one decay mode. The list of radioactive elements below will give the decay modes of all radioactive elements

Precaution steps when handling radioisotopes

1) Preparation

  • Clearly label containers, equipment, and areas for the handling of radioisotopes with radioactive labeling tape.
  • The labeling tape can be obtained from your institution stockroom or through an appropriate vendor (link to
  •  our list of vendors). Minimize radioactive material work-space.

  • Use absorbent material (benchcoat) and trays
to confine spills and reduce the spread of potential contamination.

Wear protective clothing. The minimum requirements include
a laboratory coat, safety glasses and close-toed shoes. Wear
disposable gloves, either single ordouble pair, depending on the radionuclide you are working with.Choose gloves that are appropriate for the chemical and otherhazards in your experiment.

  • Traps to collect radioactivity may be necessary (as required under some permits) (e.g.: vacuum line traps).

  • Dedicate equipment such as pipettes and glassware to radioactivity work and avoid cross contamination.

  • Plan your experiment so that mixed waste (i.e. hazardous chemical or biologically active combined with radioactivity) is not generated.

    2) Work Practices
    Change your gloves often. Assume gloves are contaminated until proven otherwise. Do not leave the laboratory or touch things outside ofthe work space with potentially contaminated gloves. Remove gloves carefully from the inside out. Ensure that gloves are disposed of properly, or touch exposed areas of skin while working in a room where radioisotopes are handled. Be careful not to rub your eyes, scratch exposed areas of skin, or touch your hair when working with radioactive material.
  • Use automatic or remote pipetting devices. NEVER pipette by mouth.

  • Allow sufficient time for frozen stock solutions to thaw before attempting to withdraw an aliquot. If you are working with 35S-methionine, Cysteine, and Translabel® refer to the related worksheet for 35S volatility.

  • Handle volatile compounds, which have the potential for vapor or gas release in a functioning hood.

  • Handle and dispose of spin (centrifuge) columns with care. Place used columns in a sealed container prior to discarding into the radioactive waste.

3) Post-Work
  • Promptly dispose of radioactive waste properly. Make a reasonable estimate of the amount of radioactivity in the waste and record on a radioactive waste tag.

  • Lock-up and secure your radioactive stock solutions immediately after use.

  • Survey yourself and work area for contamination with an appropriate survey meter. Decontaminate if necessary. Remove protective clothing and wash hands thoroughly with warm water and soap before leaving the laboratory.

  • Note the results of your survey on your personal survey record of the work area. This is required if you are working with more than 1 mCi.

  • Sink disposal must be done according to the approved guidelines. Do not exceed the posted daily limit for the radionuclide, unless otherwise authorized.

  • Participate in the bioassay program as requested.