Effects of Radiationon Human HealthISBN978-4-905025-12-2
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113-0032 東京都文京区弥生2-11-16
東京大学アイソトープ総合センター内
電話: 03-5841-3058 Fax: 03-5841-3050
E-mail: kyogikai@ric.u-tokyo.ac.jp

Factors that relate to biological effects
1. Penetrating ability
2. Linear Energy Transfer (LET)

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1. Penetrating Ability of Radiations

Paper

αP+nn P+βe-Aluminum
Acrylic resinγ
Neutronradiationn

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Lead

H 2O
(Hydrogen rich)2. Linear Energy Transfer (LET)
radiation

P+Low LET
radiations(X, γ, β)High LETradiations(α, neutron)

The energy transferred per
given distance of track

Sparsely ionizing

Densely ionizing＝Ionization

Less biological effectMore biological effecte-Linear Energy Transfer(LET)
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DNA is the Target of Radiations
Indirect action

OH.

H2O

Ionizing(free radical)eP+

Low LET
radiations(X, γ, β)Direct action
Ionizing
eP+
2nm

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High LET
radiations(α, neutron)

Classification of Biological effects of Radiations
on the Human Body
・Acute Effects vs. Late Effects
・Deterministic Effects vs. Stochastic Effects
・Somatic Effects vs. Genetic Effects

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Classification of Biological effects of Radiationon the Human Body
・Acute Effects vs. Late Effects
・Deterministic Effects vs. Stochastic Effects
・Somatic Effects vs. Genetic Effects

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Acute Effects
Symptoms of acute effects and dose delivered(Whole body, single exposure to gamma rays (or X-rays))
Dose (Gy)

Symptoms

0.25 or less

Almost no clinical symptoms

0.5

Temporary reduction of white blood cells(lymphocytes)

1

Nausea, vomiting, whole-body languor,
substantial reduction of lymphocytes

1.5Radiation sickness to 50%

1Death to 5%

4

Death to 50% within 30 days

6

Death to 90% within 14 days

7

Deathto 100%
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Late Effects

CorneaCataracts : clouding of the lens of the eyeLens

・Latent period: several years to a few decades
・Do not occur below a single exposure dose

Optic nerveof 2 Sv

EyeCancers
・Latent period: several years to a few decades

Genetic effects
・Could be･ But not verified in human beings so far
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Use a appropriate shieldin front of your eyes

Classification of Biological effects of Radiationon the Human Body
・Acute Effects vs. Late Effects
・Deterministic Effects vs. Stochastic Effects
・Somatic Effects vs. Genetic Effects

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Deterministic Effects vs. Stochastic Effects

Deterministic Effects- Acute effects- Cataract

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Stochastic Effects- Cancer, leukemia- Genetic effects

Deterministic effects
Projected threshold estimates of the acute absorbed dose for 1% morbidity after
whole body gamma ray exposures

Time todevelop effectAbsorbed
dose (Gy)Testes

3-9 weeks〜 0.1Testes

3 weeks〜6Ovaries< 1 week〜3

Depression of blood forming
process

Bone marrow

3-7 days〜 0.5

Skin reddening

Skin (large areas)

1-4 weeks< 3-6Skin burns

Skin (large areas)

2-3 weeks

5-10

Temporary hair loss

Skin

2-3 weeks〜4

Cataract (visual impairment)

Eye

Several years〜 1.5

EffectTemporary sterility
Permanent sterility

Organ/Tissue

ICRP publication 103, pp168, Table A.3.4, 2007
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Deterministic effects
Projected threshold estimates of the acute absorbed dose for 1% mortality after
whole body gamma ray exposures

Exposed population

Organ/Tissue

Time todevelop effectAbsorbed
dose (Gy)Bone marrow syndrome
without medical care

Bone marrow

30-60 days

〜1with good medical care

Bone marrow

30-60 days

2-3

without medical care

Small intestine

6-9 days〜6with good medical care

Small intestine

6-9 days>6Lung

1-7 months

6

Gastro-intestinal syndrome

Pneumonitis

ICRP publication 103, pp168, Table A.3.4, 2007
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Stochastic effects
Detriment-adjusted nominal risk coefficients after exposure to radiation at low
dose rate

Exposed population

Cancer

Heritable effectsTotal

Whole population

5.5 x 10-2/Sv

0.2 x 10-2/Sv

5.7 x 10-2/Sv

Adult workers

4.1 x 10-2/Sv

0.1 x 10-2/Sv

4.2 x 10-2/Sv

ICRP publication 103, pp53, Table 1, 2007

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Risk Estimate for Cancers (Stochastic Effect)

Actualmeasurement

Incidence ofcancer
Extrapolation

0.5%
Spontaneous
occurrence
100 mSv 200 mSv

Radiation exposure
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3 Sv

Classification of Biological effects of Radiationon the Human Body
・Acute Effects vs. Late Effects
・Deterministic Effects vs. Stochastic Effects
・Somatic Effects vs. Genetic Effects

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Somatic Effects
Effects of radiation limited to the exposed individual, as distinguishedfrom genetic effects, that may also affect subsequent unexposedgenerations.

Genetic Effects
The radiation induced change in the DNA of germ cells resulting in
the passing of the altered genetic information to future generations.

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External Exposures vs. Internal Exposures
Inhalation
Trough the skinIngestion

External exposure

Internal exposure

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Protecting Against External Exposure
3 principles

As near to the radiation
source as possible

Shield radiation sources.

ShieldingShieldStay as far away as possible.

Distance
Dose rate = K/ R2
K: constant
R: distanceTime
Keep exposure time short !
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Protecting Against Internal Exposure
Intake routes of radioisotopes

Inhalation

Ingestion
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Through the skin(wound)To Prevent the inhalation of radioisotopes

Oak Ridge-type hood

Glove box

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Prohibited Matters
Eating or drinking

Smoking

Wearing make-up

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Radiation-Related Quantities and Units
Absorbed Dose : Gray (Gy)- The energy absorbed per unit mass of the material- A fundamental dosimetric quantity (physical unit)- Regardless of the kind of radiation- 1 Gy = 1 J/ kg- Dose not reflect the degree of biological effects

To calculate the risk of irradiation to the human body

Equivalent Dose : Sievert (Sv)
Effective Dose: Sievert (Sv)

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Equivalent Dose & Effective Dose
Equivalent Dose (HT ) : Sievert (Sv)･ a measure of biological effects on a particular tissues or organs･ HT = ∑wR ・DT, RRwR ：Radiation weighting factor
DT, R ：Mean absorbed dose for a tissue or organ (Gy)Radiation weighting factor (wR)
Radiation

Weighting Factor

γ rays & Ｘrays

1Beta rays

1Proton2

α rays, fission fragments, heavy ion

20Neutrons

Continuous functionof the energy(ICRP 2007)

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Equivalent Dose & Effective Dose
Effective Dose (E) : Sievert (Sv)

Stochastic effects･ a measure of biological effects throughout the body (cancers or genetic effects)･ E = ∑w ・H = ∑w ・∑w ・DTTT
RT, RTTR

Tissue weighting factors
Tissue/OrganHT : Equivalent dose for tissues andorganswT： Weighting factor for organs or tissues

Annual average dose per person
Doctors0.24 mSv

Nurse

0.12 mSv

Radiotherapy technicians

0.68 mSv

Those engaged in research

0.01 mSv

Nuclear power plant worker

1.3 mSv
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Red bone marrow
Colon
Lung
StomachBreastGonadsBladder
Esophagus
Liver
Thyroid
Bone
Brain
Salivary gland
Skin
Others

Weighting factor
0.12
0.12
0.12
0.12
0.12
0.08
0.04
0.04
0.04
0.04
0.01
0.01
0.01
0.01
0.12
(ICRP 2007)

Effective Dose Limits and Tissue Equivalent Dose Limitsfor Radiation Workers (including Researchers)

Effective dose limit

50 mSv/year; 100 mSv/5years

Women

5 mSv/3 months

Pregnant women *1 mSv as internal exposure

Tissue equivalent dose limit
1) Lens of the eye

150 mSv/year

2) Skin

500 mSv/year

3) Abdomen of pregnant women*

2 mSv*From the confirmation of pregnancy to delivery

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Personal Radiation Monitoring
Radiation exposure report

Personal monitoring
instrument
Effective dose (実効線量)

Equivalent dose (等価線量)
for the lens, skin and abdomen
Where should a monitoring instrument be worn on?

MenWomen 大学等放射線施設協議会

End of slides

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