☰       Show/Hide Menu

☰       Department Menu

Health & Safety

Regulations For Working With Unsealed Radioisotopes

1. The Radiological Protection Institute of Ireland has issued DCU with a licence to cover custody, use and disposal of radioisotopes.

2. The School of Biotechnology and NCTCC has permission to work with the following isotopes:

IsotopeAmount in SI units (Bq)Amount in non SI units (Curie)
35S 370 MBq 10 mCi
32P 66 MBq 1.78 mCi
14C 9.25 MBq 0.25 mCi
3H 240.5 MBq 6.5 mCi
125I 3.7 MBq 0.1 mCi

3. THE LOCAL FIRE OFFICER has been notified of the location, nature and amount of all licensed radioactive sources. All isotopes must be stored in the fridge or freezer in X1.75b.


If you intend to work with radioactive isotopes, you have to contact the radiation officer Dr Rosaleen Devery in X211. Persons who have not handled radioisotopes before must go through the working routines with their supervisor. You are not permitted to commence radioactive work without familiarising yourself with the procedures in the lab. There will be an introductory course on Radiation Safety and practice run in November. Details will be posted on the web page.


Before ordering, check the supply of isotopes. Upon receipt of the isotope leave the specification sheet in the radio isotope folder in the drawer in Vestibule. An isotope record form must be completed using the template form (attached) and emailed to rosaleen.devery@dcu.ie whenever a radiochemical has been delivered.

6. ISOTOPES NOT ON THE LICENCE must not be used without seeking an amendment to the licence. Notification of intent to import and work with another isotope must be forwarded in writing one month in advance to the RPII.

7. RADIATION SUITE in School of Biotechnology

VESTIBULE (X175) Blue shoe covers (in press) to be donned upon entry.

Log Book to be filled in (ie date, isotope used, entry and exit times, comments) and signed off.

WASTE ROOM (X175a) For storage of all 32P and 35S waste

32P and 35S waste (solid) must be stored separately in perspex boxes, labelled with name and date of last addition to the box. Liquid waste must be stored in Winchester bottles and kept in Perspex box. It is each research group's responsibility to purchase suitable Perspex safety boxes. It is each research groups responsibility to dispose of waste when material has decayed.

3H and 14C liquid waste must not be stored for longer than 24 h under any circumstances. Dispose of it as you finish with it. Storage of 3H and 14C contaminated solid waste (gloves, tips etc) is not allowed under any circumstances. See Handling of Solid Waste Below

Lab X175b 32P and 35S users only at designated bay areas.

Lab X175c 14C and 3H users only at designated bay areas.The radiation suite must remain locked at all times when not in use.


Swab down with Lipsol after use. Keep work area clear after use. Store all materials eg gloves, cling film, forceps, micropipettes, tips etc in the underneath press. A Perspex box may be necessary to store micropipettes in the press.

Work in the fume hood when using radioactive material that may give rise to air-borne contamination, especially solids/solutions prepared in organic solvents. Fume hood faces must be kept down at all times to ensure proper air flow.

9. RADIOISOTOPE STOCKS & DILUTIONS must be stored in the fridge/freezer in X175b. This must be kept locked when the lab is not in use. All 32P must be kept in a Perspex box or in its original shielded container in fridge/freezer.

All radioactive substances shall be clearly identified, segregated from non radioactive substances and be securely stored.

You are not allowed to store radioactive isotopes in unmarked lab areas.

10. PROTECTIVE CLOTHING must be worn at all times (ie lab coats, gloves). Two pairs of gloves are recommended. Radiation safety badges (ie TLDs) must be worn by all 32P and 35S users in Lab X175b.

11. A SUITABLE RADIATION SURVEY METER must be available for use when working with radioisotopes. Mini monitors for 32 P should be calibrated by the RPII each year and after servicing or repair. Therefore make arrangements with RPII to get the radiation survey meter calibrated. A fee of £40 is charged for each meter. Records should be kept of the date and result of each test and a copy sent to Dr Rosaleen Devery, X211.

12. RADIATION DOSIMETER FILM BADGES (thermoluminescent badges) must be worn for work with 32 P . You receive them upon registration with the safety representative. Dosimeters are checked regularly.

13. LOG BOOK must be signed each time an isotope is used. Entries should contain date, isotope used, users name and length of time spent in lab.

14. WASTE DISPOSAL LICENCE specifies that waste containing unsealed radioactive substances shall not be disposed of unless total activity of isotope to be disposed of per day is as follows:

H3 <109 Bq or 106 kBq/kg

C14 <107 Bq or 104 kBq/kg

P32 <105 Bq or 103 kBq/kg

S35 <108 Bq or 105 kBq/kg

Note these are revised limits to our licence. The limit for P32 has been reduced. (Remember 105Bq = 2.7 mCi)

The liquid waste must be soluble/miscible in water and must be disposed of directly to the sewers.

Daily quantities disposed of should not exceed these limits. Date of disposal, isotope and activity must be recorded in the Disposal log book in the Waste room.


Each research group should have their own Perspex waste boxes for both liquid and solids clearly marked with the isotope. (eg 32P or 35S). Do not mix isotopes. This waste must be stored in the Waste room until the Geiger counter shows it to be at background level (<1 cps), i.e, it has decayed to below the set limits. The waste can then be put into the waste bin in the lab.

16. RADIATION WARNING LABELS and markings must be removed or defaced prior to disposal of waste material.


Before liquid waste is disposed of it should be counted to ensure level is within the set limit and the amount disposed of by pouring slowly down the sink with copious amounts of tap water. The tap should be left running for at least 15min after disposal. A maximum of 5L (2x2.5L) of scintillation fluid should be poured down sink daily. There should be at least 3h between disposal of each Winchester.

18. SOLID WASTE generated by 3H and 14C users must not be stored. Gloves, must be swabbed with Lipsol before removal and disposas in the ordinary waste. Pipette tips, glass pipettes, etc must be rinsed 3x in Lipsol prior to disposal in ordinary waste. Only if there is is a spillage should tissues/other solid material material containing 3H and 14C be kept/stored in the waste room in a clearly labelled container. The Radiation Safety officer must be informed if 14C or 3H solid waste has to be stored.

19. SCINTILLATION VIALS are a major source of waste. Whether glass or disposable vials are used, they should be emptied of scintillant, steeped in Lipsol and rinsed thoroufghly. Glass vials and caps may be reused.


All working space used for radioactive isotopes must be regularly checked by wipe-tests (for low b-emitters) or Geiger-counters (for strong b -emitters).

For wipe-test dip a .~4 cm filter paper in 70% ethanol. Briefly drain off excess alcohol and swab an area of .~100 cm 2 . Transfer the paper to a 20-ml counting vial and let it dry. Add 5-6 ml scintillation cocktail and shake thoroughly. Incubate in the dark for 15 min. to avoid chemiluminescence. Count for 5 min in the appropriate channel. Subtract background counts obtained with a clean filter paper treated in the same way. Record the result and report to the radiation officer.


  • Never eat, drink, put on make-up, smoke or take snuff in the lab (this is a general lab rule!).
  • Never pipette by mouth!!
  • Use protective lab-coat, gloves, shoe covers and, when feasible, a dosimeter. Don't walk about with your potentially contaminated gloves writing on computers, pushing equipment-buttons or touching door-handles!
  • Use the fume-hood if there is a risk of volatile components emitted and with high doses.
  • Prepare yourself for the experiment - make sure you have all items you require. Go through your protocol to ensure that you have everything.
  • Label special waste containers for solid and liquid waste.
  • All vessels (also sample tubes!) containing radioactivity shall be marked with isotope-labelling tape.
  • Indicate isotope, amount, date, and name.
  • Use disposable vessels as much as possible. If glassware must be used, pre-wash the vessel yourself in the sink in the Waste room (X175a) and leave it in the dish washing basket only when you have confirmed that it is contamination-free.
  • Monitor the working area before and after work. Sign the log-book.
  • Clean up afterwards so that the working space is available for the next user (another general lab-rule!).
  • This includes also pipettes, centrifuges etc!
  • The isotope labs must be clean and tidy.

If there is misuse of the labs, use of the facility will be withdrawn from the research group concerned.


  • The best protection against strong .b~and .b-emitters is distance. Your fingers are most at risk.
  • Wherever possible use forceps and work as rapidly as is safely possible.
  • Strong b~ emitters e.g. ( 32 P) should be handled behind a 1-cm-thick perspex shield ("Plexiglas").
  • Don't use lead shields as these will give rise to secondary radiation (Bremsstrahlung!).
  • 14 C and 35 S do not require shielding unless the material is in dry form.
  • 3 H requires no shielding.
  • Never work with open wounds on your hands or arms!
  • Wash your hands after handling radioactive material.


Minor spills must be cleaned up immediately - use equipment designed for use with radioactive material and disposable adsorbents only; clean with a moist tissue from the outside towards the inside of the contaminated area, perform a wipe-test on both the bench and floor and ensure that contamination is not spread.


  • Ask a colleague to help you decontaminate yourself first.
  • Prevent the spread of contamination: no one is to be allowed to leave or enter the contaminated area without checking that they are free from contamination.
  • Shield spills emitting strong b and keep as much distance as possible between you and the source


Activity 1 Becquerel (Bq) = 2.70 x 10 -11 Ci (1 Ci = 3.70 x 10 10 Bq)

  3 H 14 C 35 S 32 P
t 1/2 12.3 years 5730 years 87.4 days 14.3 days
Emax 18.6 keV 156 keV 167 keV 1.709 MeV
Emean 5.7 keV 49 keV 49 keV 0.69 MeV
biol. half-life 12 days 10 days 44 days 14 days
shielding none 3 mm perspex 3 mm perspex 1 cm perspex