1. The Internal Radiation Hazard
Lecture is split into two parts :
Internal and external hazard.
Janice Thompson, University Radiation Protection Officer

2. Janice Thompson, University Radiation Protection Officer
Internal Hazard
Internal contamination with unsealed radioisotopes can happen through various routes:
Inhalation - Commonest cause of intake
Ingestion - can occur by transferring a radioisotope from contaminated fingers to mouth
Injection - usually result of careless handling or disposal of hypodermic needles
Absorption - can occur if tritiated water or radioiodine is splashed onto skin.
Working with open or unsealed sources of radioactive material, your faced with possibility radioactive material might find its way into body, causing internal radiation hazard. It’s only thru combination of physical & biological half-life that material can be eliminated from body - some may remain there forever. Internal contamination more dangerous than external. You cannot remove yourself from source, irradiation occurs 24 hrs a day.
Routes of entry into body are via mouth by inhalation or ingestion, and also through injection or absorption.
Inhalation - Commonest cause of intake and usually results from neglect of hazard caused by radioactive gases and aerosols. e.g. use of tritiated compounds may lead to tritiated water vapour from an experiment. Similarly C-14 may give rise to radioactive CO2. Catching droplets from a pipette or column with a beaker will produce an invisible aerosol cloud. All of these procedures should be carried out in a fume cupboard.
Ingestion - can occur by transferring a radioisotope from contaminated fingers to mouth, another common method is inadvertent contamination of a drinking vessel placed nearby the experiment - hence the ban on eating, smoking, drinking and applying cosmetics in the lab.
Injection - usually result of careless handling or disposal of hypodermic needles, pipette tips or glassware. Care should be exercised when packaging waste to ensure that these items are properly protected. Used needles and broken glassware should be disposed of in a ‘sharps’ container.
Absorption - can occur if tritiated water or radioiodine (in the form of potassium iodide) is splashed onto skin.
Janice Thompson, University Radiation Protection Officer

3. Janice Thompson, University Radiation Protection Officer
Avoid internal hazard by using personal protection equipment :
Lab coat
Safety glasses/face shield
Disposable gloves
Disposable apron
Appropriate radiation shield
Personal dosimeter
Finger Badges
Eye Badges
You can help to avoid internal hazard by using personal protection :
Wearing lab coat, safety glasses/face shield, disposable gloves, disposable apron, use of appropriate radiation shield & fume cupboard, if appropriate.
Additionally :
Personal dosimeter - Under IRR99 only “classified” radiation workers are required to wear a dosimeter. However, all radiation workers in University are issued with a dosimeter to record any external ionising radiation. It should be worn at level of top pocket of a lab coat as exposure of eyes to beta radiation is principal external radiation hazard in most laboratories.
Finger Badge - Designed to record dose received to fingers during dispensing of radioactive materials. Any worker who regularly exceeds handling limit or is performing a new technique should wear one of these badges. Consider their use for some isotopes e.g. P32.
Janice Thompson, University Radiation Protection Officer

4. Precautions in the Use of Unsealed Radioactive Materials
Setting up the experiment :
Use the least radiotoxic isotope
Use the minimum activity required
Know the physical and chemical properties of the isotope
Use ‘dummy’ run experiments without radioisotopes
Precautions in the use of unsealed isotopes:
In order to minimise the exposure to ionising radiation, you need to appreciate the properties of ionising radiation and the principal hazards which they can present.
Radioactive material can only be used within clearly demarcated area. Although working procedures are designed to minimise the amount of contamination, it must be assumed that any item or surface within a radiation demarcated area may potentially be contaminated.
When you are setting up the experiment:
Use the least radiotoxic isotope
Use minimum activity required to get good counting statistics.
Know the physical and chemical properties of the isotope
Use ‘dummy’ run experiments without radioisotopes i.e. use water
Janice Thompson, University Radiation Protection Officer

5. Janice Thompson, University Radiation Protection Officer
Working Procedures :
Lab coats and gloves must be worn at all times and avoid touching areas of uncovered skin with a gloved hand
Cover work surfaces with disposable absorbent materials, benchkote and use an extra degree of containment, such as a tray
Use a fume cupboard if there is any risk of releasing gas, dust, aerosols, etc.
Eating, drinking, smoking or applying cosmetics are prohibited.
Work must not be carried out by a person with an undressed cut or abrasion below the wrist.
Monitoring for contamination radiation levels must be carried out routinely.
Gloves and clothing must be monitored after handling radioactive materials, it is essential if there’s a spillage
Hands must be washed before leaving the laboratory after handling radioactive materials.
Working Procedures:
Nearly all the contamination that can be transferred onto and into the human body is caused by the working procedures adopted by the individual. In order to reduce the risk, the following working procedures must be adhered to in the work area:
Lab coats and gloves must be worn at all times and avoid touching areas of uncovered skin with a gloved hand
Cover work surfaces with disposable absorbent materials, benchkote and use an extra degree of containment, such as a tray
Use a fume cupboard if there is any risk of releasing gas, dust, aerosols, etc.
Eating, drinking, smoking or applying cosmetics are prohibited.
Work must not be carried out by a person with an undressed cut or abrasion below the wrist.
Monitoring for contamination radiation levels must be carried out routinely.
Gloves and clothing must be monitored after handling radioactive materials, it is essential if there’s a spillage
Hands must be washed before leaving the laboratory after handling radioactive materials.
Janice Thompson, University Radiation Protection Officer

6. Working Procedures Continued :
Apparatus used for radioactive materials must be labelled with radioactive tape.
Radioactive waste must be placed in an appropriate container and its activity recorded, along with relevant dates
Containers for radioactive materials must not be directly held in the hand if this would cause significant doses to fingers.
Radionuclides emitting penetrating radiations must be adequately shielded.
Distance yourself from a radioactive source
Records must be kept of all stocks and radioactive waste
Contamination must be cleared up without delay.
Apparatus used for radioactive materials must be labelled with radioactive tape.
Records must be kept for all isotopes indicating their arrival, usage, details and final disposal
Waste must be placed in an appropriate container and its activity recorded, along with the relevant date
Containers for radioactive materials must not be directly held by hand - this would cause significant dose to fingers.
By distancing yourself from a radioactive source, the dose to your body and extremities is greatly reduced – inverse square law
Radionuclides emitting penetrating radiations must be adequately shielded. Shielding will reduce the dose that the worker is being exposed to as well as keeping it under the adequate shielding limit which is 7.5Svhr-1
Contamination must be cleared up at the time.. If not cleared up at the time then there is a strong possibility that the contamination will spread, as well as exposing the worker to a higher dose than was necessary.
Janice Thompson, University Radiation Protection Officer

7. Janice Thompson, University Radiation Protection Officer
Radioactive Waste
Three Routes for Disposal :
1. Liquid waste, via disposal sink.
2. Solid waste to authorised contractor, via RPS.
3. Gaseous disposal, via authorised fume cupboard.
Radioactive Waste
Every experiment will produce radioactive waste, it is very important that this is dealt with properly.
Three routes for disposal :
1. Liquid waste - down disposal sink – very cheap!
2. Solid waste -to authorised contractor via RPS - expensive!
3. Gaseous - disposal via authorised fume cupboard – limited! i.e. typically fume cupboards < 400 Bq per cubic meter
Taking each one in turn …
Janice Thompson, University Radiation Protection Officer

8. Dealing With Radioactive Waste
Radioactive Liquid Waste
Aqueous waste should be diluted before disposal
Use only marked disposal sinks
Run water through sink to disperse waste (avoid splashes)
Log all activity discharged – very important
SEPA will ask you to justify your disposal figures
Do not exceed your monthly disposal limits - expensive!
No organic solvents
Radioactive Liquid Waste
Aqueous waste should be diluted before disposal and you should only dispose of this in the designated disposal sinks.
Run water through sink to disperse waste (avoid splashes).
Log all activity discharged – legal requirement & very important!
Remember that each sink will have a monthly sink limit - find out what this is.
Do not exceed your monthly disposal limits
If you deliberately dispose of more waste than is allowed then this is a criminal offence and you (and the University) could be liable for prosecution
SEPA will ask you to justify your disposal figures, gestimates not allowed.
Must be able to demonstrate how you worked out disposal figures.
No organic solvents down the sink
Janice Thompson, University Radiation Protection Officer

9. Radioactive Solid Waste :
Segregate waste into 3H/14C; 32P; others.
Dispose to marked bins only.
Do not put non-radioactive waste into these bins.
Do not put biohazard waste into these bins.
Do not put radioactive waste into ‘normal’ waste bins.
Contents of bins must be labelled.
Units must be in Bq, kBq, MBq etc – legal requirement.
Solid waste :
Segregate the waste into 3H/14C, 32P & others.
Dispose only in marked bins - you must not put radioactive waste into ordinary bins.
Disposing of waste is expensive - so ordinary non-contaminated waste should not be put in with the radioactive waste.
Do not put biohazard waste into these bins.
The waste should be monitored and an accurate account should be made of the activity.
Contents of bins must be labelled.
Units must be in Bq, kBq, MBq etc – legal requirement.
Janice Thompson, University Radiation Protection Officer

10. Radioactive Waste Label
Label must be filled in fully, stating:
type of isotope
activity in MBq, taking half life in to account.
College, School & lab
Liquid or solid or scintillant waste
And date!
Janice Thompson, University Radiation Protection Officer

11. Contamination Monitoring
Monitor after use:
Spill tray
Work area
Bench, floor
Lab Coat
Gloves
Shoes
Contamination Monitoring, Areas to monitor after use -
Spill tray
Work area
Bench, floor
Lab Coat
Gloves
Apart from 3H, contamination monitor be on & used throughout manipulation of radioactive material. Worker should be aware of monitors response to radiations present.
Check battery prior to use. Do not switch on and off, gives better performance if left on until experiment is finished. Use monitor to check items of equipment for contamination and check the fingers frequently.
End of experiment, tidy away apparatus – check for contamination. Monitor spill tray, working area, front of bench and floor. Hold probe close to surface being monitored and do not move too quickly. Listen for variations in number of ‘clicks’ on monitor loudspeaker, scan methodically and home in on any spots of contamination found.
Contamination spots can be marked as check proceeds and then decontaminated at end of the search. When decontam, work in from least contamin part to most active and avoid spreading contamin by excessive use of ‘Decon’. Tissues or cloths soaked in Decon and placed over an effected area can be very effective in removing contamination. Mark area with tape.
Contamination should be kept as low as reasonably practicable. ‘Action Level’ for surface contamination levels is 3 Bqcm-2, contamination above this level is deemed to be unacceptable and will require decontamination procedures to be taken. Each monitor in current use will have label attached to side giving monitor's response to 3 Bqcm-2 level. Note that figures quoted are response above background.
Janice Thompson, University Radiation Protection Officer

12. Decontamination Areas
Decontaminate areas with Decon and work ‘out to in’
‘Safe’ level is about 3 Bq/cm2
‘Fixed’ contamination must not exceed 3.5 Svhr-1
Skin Contamination
Wash (not scrub) skin with soap and running water
Do not use Decon on skin
Do not break the skin
Report all accidents and spillage's immediately to your local RPS.
If they are not available contact the University Radiation Protection Service (4471/5878) for advice
Decontamination Summary
Decontaminate areas with Decon and work from the outer area of spillage to the inner area.
Keep monitoring as you decontaminate the area. Remember to monitor gloves as well.
‘ Safe’ level is about 3 Bq/cm2 - ‘Fixed’ contamination must not exceed 3.5 Svhr-1
Skin Contamination
Wash (not scrub) skin with soap and running water – do not damage or break the skin.
Do not use Decon on skin - irritant to skin
Do not break the skin – this may cause contamination to enter blood stream
Report all accidents and spillage's immediately to your local RPS.
If they are not available contact the University Radiation Protection Service (ext 4471) for advice
Janice Thompson, University Radiation Protection Officer

13. Radiation Protection Organisation
Radioactive Spillages - S.W.I.M
Stop the spillage
Warn other personnel.
Isolate the area.
Minimize the exposure to radiation and contamination.
Spreading of radiation beyond spill area can occur by movement of personnel involved in spill or cleanup effort. Can prevent spread by confining movement of personnel until they’ve been monitored & contamination free. Minor radiation spill - lab staff can handle safely without assistance of RPS. All other radiation spills are considered major. Call RPS, ext 4471 to ensure procedures are being taken to clean up the spill.
Minor Radiation Spill
Wear protective equipment, safety goggles, disposable gloves, shoe covers, and long-sleeve lab coat, to reduce personnel contamination.
Mark off area which is contaminated to confine the spill.
Notify personnel in the area about the contamination and keep non-essential personnel out of the area. Notify Local Radiation Supervisor.
Decontaminate from the outside of the spill area towards the centre to avoid spreading contamination.
Place absorbent paper towels over liquid spill. Areas should be decontaminate with Decon.
Using forceps, place towels in plastic bag. Dispose in radiation waste container.
Monitor area, hands, and shoes for contamination with an appropriate survey meter or method.
Repeat cleanup until contamination is no longer detected.
‘Safe’ level is about 3 Bq/cm2. ‘Fixed’ contamination must not exceed 3.5 Svhr-1
Make a complete record of the decontamination process. Monitor the area to ensure thorough decontamination.
Major Radiation Spill
Attend to injured or contaminated persons and remove them from exposure.
Alert people in the laboratory to leave the immediate area. Notify RPS (4471).
Have potentially contaminated personnel stay in one area until they have been monitored and shown to be free of contamination.
Close doors and prevent entrance into affected area.
Have person knowledgeable of incident and laboratory assist emergency personnel.
Janice Thompson, University Radiation Protection Officer

14. Janice Thompson, University Radiation Protection Officer
Summary :
The internal hazard is the principal hazard encountered in the use of unsealed radioactive materials.
There is NO shielding from an internal intake.
There is NO distance protection from an internal intake.
Irradiation occurs 24 hours/day.
Summary :
The internal hazard is the principal hazard encountered in the use of unsealed radioactive materials.
There is NO shielding from an internal intake
There is NO distance protection from an internal intake.
Irradiation occurs 24 hours/day.
Emissions will be dissipated in the cells of the body
Certain isotopes will concentrate in particular organs.
Emissions will be dissipated in the cells of the body.
Certain isotopes will concentrate in particular organs.
Janice Thompson, University Radiation Protection Officer