Instructions for working with radioactivity

Below, some general and practical advice is given concerning the handling of isotopes which are used in our laboratories at present. Whenever a new isotope is introduced, it will be included in the collection.

It is taken for granted that when working with isotopes, the safety rules which apply for working with hazardous chemicals also apply here, i.e., wear lab coat, gloves, safety goggles (when required), etc. Furthermore a thermoluminescent dosimeter (TLD/TL dosimeter) must be worn, either a personally registered dosimeter with quarterly/monthly checking, or an extra dosimeter that can be used by other persons as required and then sent for checking after use. The Government Bill 823 of 31 October 1997 form the basis for these rules. In contrast to the earlier Bill, the maximum allowed dose per person has been lowered to 20 mSv, and there are special rules for working with radioactive substances while pregnant (see next page).

Units of Activity:                         1 mCi = 37 MBq 1μCi = 2.2 x 106 dpm (decay per minute)

                                                 1 MBq = 27 μCi 1 Bq = 1 dps (decay per second)


List of isotopes emitting β-particles


Maximum energy

Half-life time

Radionuclide group


0.018 MeV

12.3 years



0.159 MeV

5760 years



0.167 MeV

87.2 days



1.71 MeV

14.3 days



0.249 MeV

25.4 days



After storage for 10 half-lives, the radioactivity is decreased to about 1/1000. This will often be an appropriate time for contaminated glassware and other highly radioactive waste.

In the INANO house, p.t. (July 2015) only isotope labeled with 32P isotope

The INANO house has a S1 1/10 permit. This permission entitles to storage of up to 500 MBq 32P

Protection against radiation

For β-particles, the maximum range is dependent on the particle's energy. The particle is slowed down, and the heavier the braking substance, the quicker the particles are slowed down. Please be aware that the absorption of particle radiation in a heavy absorber gives a more powerful braking radiation than absorption in a light absorber. Plexiglas therefore offers better protection against 32P than ordinary glass.

Range and necessary shielding for selected isotopes:




Shielding thickness


0.006 mm

6 mm

Not necessary


0.3 mm

30 cm

1 cm perspex


0.28 mm

24 cm

1 cm Perspex


0.8 cm

720 cm

1 cm Perspex




0-1 cm perspex




3 mm lead or lead glass


Storage of radioactive substances

Radioactive material must be stored in the refrigerator or freezer in an isotope laboratory, and must be registered in the isotope inventory database (The “HOT” database). The cabinets are fitted with locks. In the INANO House, 32P material is stored in room 1592-319, which functions as S1/10 laboratory. Niels Sandal (MBG) has the overall responsibility. 

When planning to purchase radioactive material, the purchaser is responsible for making sure that the total allowable inventory for each isotope is respected. This information can be found in the database, KIROS, which is the department’s chemical registration system  ( The purchaser is also responsible for registering all new purchases in this database, and all users must make sure that they register in the database every time they use any of the stored isotope.

Maximum limits for work with radioactivity

If there is a C-laboratory in the building, work with S1/100 quantities can be done in all other laboratories. If activity levels exceeding the S1/100 limits are to be applied, it is possible to apply for dispensation for S1/10 classification. An application is required for each isotope.


32P, 14C, 33P

MBq / μCi in use at any one time simple wet procedures

Wet procedures

Procedures with dry material



50 / 1350

5 / 135

0,5 / 13,5

Below are examples of what can be defined as:

·         "simple wet procedures": Extraction from stock solutions, dilutions.

·         "wet procedures": Normal experiments.

·         "procedures with dry material": Work involving a certain risk: chromatograms, evaporation, dry gels.

The term ”in use at any one time” means the maximum amount of activity that can go on in any one laboratory at any given time. If several experiments are going on at the same time in the same laboratory, then the maximum amount per experiment must be reduced to compensate for an increased risk of contamination and accident.

The maximum amount of radionucleotide that can be stored in a laboratory is the same as that stated for a wet procedure

Guidelines for working with isotopes

·         Upon extraction from vials with rubber cap: Always insert a needle with a cotton wool in the ampoule before use to equalise pressure differences (many compounds have been on dry ice and therefore assume considerable pressure by warming to room temperature).

·         General care must of course be shown. Always use plastic trays, gloves, etc. when working with isotopes. 

Guidelines for working with isotopes 32P and 33P

·         32P-ampoules must always be stored in a lead container.

·         All work with isotope amounts larger than 1 mCi (40 MBq) must be carried out in an isotope laboratory. Handling of the isotope must take place behind a plexiglass or a similar screen. Work with small amounts of isotopes can be carried out in S1 or S1/10 laboratories.

·         Always use a plexiglass tray and use nitrile gloves.

·         Avoid using glass when working with 32P, because “Bremsstrahlung” can be formed.

·         Always keep a monitor beside you.

·         Check yourself and the work top with the monitor frequently, e.g. every time you leave the area.

·         The whole laboratory must be checked with a monitor once a week and the results recorded in a special protocol to be found in the laboratory.

·         Use a plexiglass box or lead container for transport between laboratories. 

Disposal and cleaning-up after working with 32P and 33P

·         Liquid waste must be diluted to < 2.7 μCi (0.1 MBq) per litre and poured down the sink. Afterwards let water run down the sink for about 5 min. The maximum monthly limit that can be disposed of in the sink is 1.35 mCi (50 MBq) per permit.

·         Liquid waste, which in addition to 32P contains organic solvents (phenol), should be collected in a fume cupboard (e.g. in a special plastic container together with other phenol waste) until the isotope has decayed. It is then disposed of according to the Departmental rules.

·         All solid waste contaminated with 32P must be collected. Use the plexiglas containers in the isotope laboratory. Very weakly contaminated things (gloves, etc.), can be thrown into the usual hazardous waste boxes. All fluid waste, marked with group name and date, must be cleared away after six months.

·         Contaminated objects can be washed with Decon (use only the sink in the isotope laboratory). When there is no trace of contamination, they can be sent for washing. If there is still contamination, put them to soak in a decontamination bath overnight. If this is still not sufficient, store the objects for 10 half lives.

·         Cleaning-up the work area: Check the work area with a monitor and decontaminate any contaminated places. Remember that an isotope laboratory does not necessarily have to be contaminated!

·         32P waste from the isotope laboratory is stored in plastic container for approx. 10 half lives (5 months).

·         The box is sent for incineration when the total radiation level is less than 1.3 mCi (50 Mbq) inside and the radiation is less than 5 μSv on the outside.

Guidelines for working with radioactive substances while pregnant or breast feeding 

The working schedule for pregnant women should be such that an unborn child is not subjected to more than 1 mSv. The State Department for Radiation Safety recommends the following maximum limits: 

 32P                                                   5 MBq ~ 135 μCi

3H, 14C, 33P and 35S                      50 MBq ~ 1.35 mCi

dositometry films must be changed once a month.

If a pregnant woman works in a laboratory where colleagues are using open radioactive sources, then the dosage and risk should be seen as the total exposure. The Department of Occupational Medicine (Arbejdsmedicinsk Klinik) can be consulted regarding an evaluation of the risk involved.

When a woman is breast feeding at the time she is working with radioactive substances, she should be aware that in the event of accidental spill, radiation may be transferred to the child through the breast milk. If the amount used is less than the limits for an S1-classification, then the risk is very small.

Accidents with radioactive material

Spill or loss of radioactive material

It is the responsibility of the person who spills to make sure that the spill is cleaned up immediately and thoroughly. If the spill is considerable and over a large area, then an Occupational Health and Safety representative/supervisor and the isotope-responsible staff member must be contacted. A small spill of liquid radioactivity should be wiped up with absorbent paper (paper towel). Spills of powder or other dry material should be wiped with wet absorbent paper. Afterwards, wash with a carrier-solution, i.e., a non-radioactive solution of the labelled substance that was spilled. For 32P-spills, a potassium phosphate solution should be used.

All paper as well as other materials used for cleaning-up should be treated as solid radioactive waste. 

After cleaning-up, check the area for radioactive contamination. 32P and 33P can be checked directly with a monitor, but because of the monitor’s low sensitivity for 33P, - beta radiation, an extra precaution for these is to wipe the area with a damp filter paper, dry the paper, put in a scintillation vial with 5 ml scintillation fluid and count in a scintillation counter.

Radioactive contamination of persons

Persons, who frequently work with or nearby 32P, must wear a dosimetry film. The Danish National Institute of Radiation Protection sends the dosimetry results every month and a yearly statement. The limit is 20 mSv/year, although during pregnancy, the limit is 1 mSv, (see Guidelines for working with radioactive substances while pregnant or breast feeding). 

Gloves must always be worn when working with radioactive isotopes, and hands must be washed thoroughly afterwards. However, in the event of contamination of the skin, the area should be washed a number of times with a carrier-solution and then several times with soap and water. If there is still sign of contamination (monitor), you should go immediately to the hospital’s casualty ward.

If the skin is damaged, as well as radioactively contaminated (corrosion or sores), rinse liberally with water, possibly opening the sore to induce bleeding and cleansing. Immediately afterwards go to the hospital’s casualty ward. 

Clothing which has become severely contaminated should be treated as radioactive waste.

Ingestion of radioactive substances

If you accidentally swallow a radioactive solution, vomiting should be induced immediately (finger down the throat) and go immediately afterwards to the hospital’s casualty ward. 

Useful phone numbers

The National Institute of Radiation Hygiene: 24-hour security 0 - 4494 3773, must be contacted for major accidents with radioactive isotopes.

No urgent inquiries and questions:  Security Partner 0 - 70 113 113

Reference: "Vejledning om strålebeskyttelse ved arbejde med åbne radioaktive kilder", Statens Institut for Strålehygiejne, 2005 (Guidelines for protection from radiation while working with open radioactive sources), and "Bekendtgørelse om anvendelse af åbne radioaktive kilder på sygehuse, laboratorier m.v.", Bekendtgørelse nr. 954 af 23. oktober 2000 fra Sundhedsstyrelsen. (Act on the use of open radioactive sources in hospitals, laboratories, etc.).