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Radiation Safety and Biology > Week 8 part 2 > Flashcards

Week 8 part 2 Flashcards

1
Q

What is the risk of Neonatal deaths in humans compared to normal incidence?

A

200-500 deaths per million exposed to 10mSv

compared to 2500 per million (unexposed)

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2
Q

What is the probability of severe mental retardation, compared to normal incidence of mental retardation?

A

40% (or 4 hundred thousand) incidence at 1 Gy per million exposed

compared to 5000 per million exposed

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3
Q

Is mental Retardation a deterministic effect? If so , why?

A

Yes, because there is likely threshold of 0.2 Gy

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4
Q

What is the observed shift in IQ (due to pregnancy radiation)?

A

30 per Gy (during the sensitive period

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5
Q

What is the Largest study regarding in utero irradiation and childhood cancer?

A

The Oxford Study

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6
Q

What is the Oxford Study?

A

Considered approx 8,000 cases of malignant childhood death (looked into radiological history of mother during pregnancy)

+ compared it to data for children who died <10 years from a malignant disease

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7
Q

What did the Oxford Study find?

A

Obsetric Radiography resulted means increased risk of malignancy in childhood

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8
Q

Besides the oxford study, where do we get in-utero related childhood cancer data?

A

Limited data from A-bomb survivors (1620 prenatally exposed)

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9
Q

Are the findings of the oxford study backed up by A-bomb survivors?

A

Yes

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10
Q

The risk estimate for the prenatally exposed (due to a-bomb) was?

A

200-250 deaths (before age 10) from cancer, per million exposed in utero

-1/2 of these were leukemia

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11
Q

Being exposed in what trimester, has the greatest risk?

A

the first trimester

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12
Q

What is the natural incidence of fatal childhood cancer?

A

1 in 2000

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13
Q

What is a limitation of collected data regarding, in utero radiation?

A

We don’t have the full picture of true cancer as the total risk period is 20 years

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14
Q

Which type of cancer’s risk of incidence of doubled due to in utero radiation?

A

Leukaema

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15
Q

Is an adult, child, or embryo most sensitive to cancer induction?

A

Embryo

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16
Q

Once a pregnancy is known by a radiation worker, and reported to management, what happens next?

A

The total dose of the worker becomes the same as the public

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17
Q

Go to slide 24 on week 8 and memorise table

A

do it

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18
Q

Where do we get our data for genetic effects?

A

virtually NO human, mostly animals

19
Q

Does radiation produce the same type of mutations as those observed in natural incidence?

A

Yes

20
Q

Data of A-bomb survivors failed to show any statistically significant increase in what?

A
  • Congenital abnormalities
    -cancer
    -chromosome aberrations
    -mutational blood protein changes
    BUT… we don’t have enough human data to be “statistically significant”
21
Q

What are the reasons for low human data on genetic effects of IR?

A
  • Long life cycle
  • studies require large population > 1 million
  • too few offspring in families
  • large incidence of natural genetic damage
22
Q

Is there ample evidence of IR causing heritable mutations in plants and animals?

A

yes there is, therefore we must assume the same for humans

23
Q

A recent study of Hiroshima survivors and their offspring concluded what?

A

All indiactors of data, concluded that genetic damage my result from exposure to IR

24
Q

Indicators of A-bomb survivors included?

A
  • untoward pregnancy outcome
  • death of a live born child < 17 years
  • sex chromosome aneuploidy
25
Q

What did early results of IR exposure (on insects) indicate?

A

1) there is no threshold
2) the dose/effect relationship is proportional
3) there is no effect of fractionation
THIS INDICATES THERE IS NO REPAIR

26
Q

What is the summary of information gained from the MEGAMOUSE EXPERIMENT? (name 4)

A

1) different gene loci have different rates of induction and mutation
2) mutation frequency is dose-rate and sex dependent
3) time between irradiation and conception is important
4) magnitude of the effect depends on stage of sex cell

27
Q

Out of the 7 loci studied what was the variation factor of genes?

A

35- different gene loci have different rates of induction + mutation

28
Q

At high dose rates >1 Gy/min, do the spermatogonia and oocytes have a similar sensitivity?

A

Yes

29
Q

What happens as the dose rate decreases to <10^-2?

A

Both male and female sensitivity decrease BUT the oocytes decreases far more than sperm

30
Q

At low dose rates, is the mutation frequency in oocytes distinguishable from natural incidence? (compared to IR)

A

No, even for several Gy

31
Q

On average are male cells more sensitive than females to IR?

A

Males are more sensitive and carry genetic burden at low dose rates

32
Q

How can you reduce the effect of IR?

A

Delaying time between conception after IR exposure (due to repair)

6 months assumed to provide safety margin

33
Q

The latter stages of male and female sex cells are more sensitive by approx how many times compared to early stages?

A

latter stage are 5 times more senitive

34
Q

How are risk estimates of genetic damage expressed in relative terms?

A
  • The doubling dose
    (radiation dose doubles at random rate)
  • or in absolute terms
    (no. mutations per million per 10mSv)
35
Q

What is the doubling dose risk for low dose rate exposure? (in humans)

A

1 Gy

36
Q

What is the absolute risk for low dose rate in whole population?

A

100 mutations/ million births/10mSv of parental exposure

37
Q

What is the absolute risk for low dose rate in working population?

A

60/million/10mSv

38
Q

In males and females, what dose causes temporary sterility?

A

0.2 Gy females

150 mGy males

39
Q

In males and females what dose causes permanent sterility? (sundry effects

A

4 Gy females

6 Gy Males

40
Q

In females what dose may delay menstruation? (sundry effects)

A

0.1 Gy

41
Q

What dose causes cataract formation? is there a threshold? and what is the latent period? (sundry effects)

A

1-2 Gy
>10 Gy get 100% induction
-latent period of 6 months to 30 years

42
Q

What dose causes skin damage? Explain the two waves of effects?

(sundry effects)

A

3-10 Gy
mild erythema subsides followed by a second wave

*>10 gy
second wave maybe followed by desquamation

43
Q

dose causing epilation? (sundry effects)

A

3-4 Gy

Radiation Safety and Biology (2 decks)

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