radiocarcinogenesis

Question 1

What countries do you think have conducted nuclear weapon tests?

Answer 1

usa, ussr uk france china india north korea. pakistan

Question 2

Effects of Radiation on DEVLEOPING EMBRYO

Answer 2

Human Sources
Japanese A bomb Survivor Cohort Studies
Therapy patients
Animal Studies

Teratogenic effects
Pre and neo natal death
Growth retardation
Abnormalities
Post natal induction of cancer

Preimplantation stage (conception – two weeks)
Organogenesis stage (two – eight weeks)
Foetal stage (nine weeks – delivery)

Question 3

Pre-implantation Stage

Answer 3

Period from conception until fertilised egg attaches to the uterus wall (generally two weeks).

Irradiation at this stage “all or nothing” effect.
Pre-natal death most significant risk.
Embryos that survive, usually develop normally.

A dose as low as 0.05 Gy can kill at this stage.

LD50/30 is 1 Gy at this stage (based on studies in mice)

No birth defects were found in Japanese A bomb survivors as a result of irradiation during this stage

Question 4

Organogenesis Stage

Answer 4

Organogenesis – development of major organs
Pre-natal death reduced rate
Risk due to congenital abnormalities
Growth retardation may recover after birth
Most sensitive at start of period rather than end
Weeks 2 - 5. Skeletal defects – stunted limbs, polydactyly, oligodactyly
Weeks 6 - 8. CNS defects – anophthalmia, ancencephaly, exencephaly
0.2 Gy can increase abnormalities.

LD50/30 is 1.5 Gy at this stage (based on studies in mice)

Congenital deformities naturally 6%. Large doses of radiation increase this to 7%

Question 5

Foetal Stage

Answer 5

Period nine weeks onwards
Incidence of prenatal death and abnormalities is very low
Death as a result of irradiation, often occurs after birth with the newly born developing ARS symptoms
Growth retardation more likely to be permanent

LD50/30 is 2 – 3 Gy at this stage (based on studies in mice)

As the foetus nears delivery, the LD50/30 increases to post natal figures

Question 6

CSP 5: X-rays in Medical Diagnosis. Individual Dose Limits

Answer 6

3.5 Radiation personnel
An effective dose of 20 mSv per year averaged over any five (5) year period and 50 mSv in any one year.
An equivalent dose of 500 mSv to the skin (at the nominal depth of 7 mg/cm²) averaged over 1 cm², regardless of the total area exposed, in any one year.

An equivalent dose of 150 mSv to the lens of either eye in any one year.

An equivalent dose of 500 mSv to the hands and feet in any one year.

Question 7

MRT Risks

Answer 7

Life Span Shortage
12 days less

Cataracts
No affect but protective glasses if spend a lot of time in interventional work

Cancer
At 0.5mSv, risk of 1 : 40,000. (Natural incidence is 1 : 3)

Leukaemia
Recent research as shown no link between occupational exposure and leukaemia