Effects of Radiation on Human
HealthNagara Tamaki, MD,PhD
pof Nuclear Medicine,,
Department
Graduate School of Medicine
ISBN978-4-905025-12-2
大学等放射線施設協議会

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

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

大学等放射線施設協議会

Classification of Biological effects of Radiationon the Human Bodyy・Acute Effects vs.
vs Late Effects
・Deterministic Effects vs.
vs Stochastic Effects
・Somatic Effects vs.
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 (mSv)

Symptoms

250 or lless

Almost no clinical symptoms

500

Temporary reduction of white blood cells(lymphocytes)

1,000

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

1,500

Radiation sickness to 50%

1,000

Death to 5%

4,000

Death to 50% within 30 days

6,000

Death to 90% within 14 days

7,000

Death to 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 2,000 mSv

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 Bodyy・Acute Effects vs.
vs Late Effects
・Deterministic Effects vs.
vs Stochastic Effects
・Somatic Effects vs.
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
p effectAbsorbed
dose ((mSv))

Testes

3-9 weeks〜 100Testes

3 weeks〜 6,000

Ovaries< 1 week〜 3,000

Depression of blood formingprocessp

Bone marrow

3-7 days〜 500

Skin reddening

Skin (large areas) 1-4 weeks< 3,000-6,000

Skin burns

Skin (large areas) 2-3 weeks

5,000-10,000

Temporary hair loss

Skin

2-3 weeks〜 4,000

Cataract (visual impairment)

Eye

Several years〜 1,500

EffectTemporary sterility
Permanent sterility

Organ/Tissue

ICRP publication 103, pp168, Table A.3.4, 2007
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Risk Estimate for Cancers (Stochastic Effect)

Actualmeasurement

Incidence ofcancer

From the data of thevictims of atomic bomb
casualties

Extrapolation

0.5%
Spontaneousoccurrence
100 mSv 200 mSv

Radiation exposure

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3 Sv

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

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Somatic Effects
Effects of radiation limited to the exposed individual, as distinguishedfrom ggenetic effects,, that mayy also affect subsequentq
unexposed
pgenerations.

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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1. Penetrating Ability off Radiations

PPaperαP+nn P+βe-Aluminum
Acrylic resinγ
Neutronradiationn

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L dLeadH2O(Hydrogen rich)Protecting Against Internal Exposure
Intake routes of radioisotopes

Inhalation

Ingestion
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Through the skin(wound)Radiation-Related Quantities and Units
Absorbed Dose : Gray (Gy)- The energy absorbed per unit mass of the material- A fundamental dosimetric q
quantityy (p(physicalyunit))- 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
Eff ti Dose
Effective
D: Sievert (Sv): Sievert
Sit (Sv)(S )大学等放射線施設協議会

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

1

Beta rays

1

Proton2

α rays, fission fragments, heavy ion

20Neutrons

Continuous functionof the energy(ICRP 2007)

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

Stochastic effects･ a measure of biological effects throughout the body (cancers or genetic effects)･ E = ∑w ・H∑wR ・DDT,T HT = ∑wT・∑w
T RTTRHT : Equivalent dose for tissues andorgans
wT： 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
0.01

Nuclear power plant worker

1.3 mSv
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Tissue weighting factors
Tissue/Organ
Weighting factor
Red bone marrow
0.12
Colon0.12
Lung0.12
Stomach0.12
Breast0.12
Gonads0.08
Bladder0 04
0.04
Esophagus
0.04
Liver0.04
Thyroid
0.04
Bone0.01
Brain
0.01
Salivary gland
0.01
Skin
0.01
Others0.12(ICRP 2007)

Risk Estimate for Cancers (Stochastic Effect)

Actualmeasurement

Incidence ofcancer

From the data of thevictims of atomic bomb
casualties

Extrapolation

0.5%
Spontaneous
occurrence
100 mSv 200 mSv

Radiation exposure

大学等放射線施設協議会

3 Sv

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

g
y to delivery
y*From the confirmation of ppregnancy

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Radiation burden in our life
• Natural radiation 3 mSv/year
y(average)g(cosmic ray, earth, air, and food, etc)
• Medical diagnostic use 3 mSv/year (average)
chest X-ray0.06～0.3 mSv
X-ray ＣＴ
10～50 mSv
Benefit > Risk
Nuclear scan 2～15 mSv(I-131 thyroid scan 13 mSv)
• Cancer treatment
I-131 thyroid cancer treatment 2,000～4,000 mSv
Local radiation
40,000～60,000 mSv

Possible Biological Effect after Disaster ofF k hi
Fukushima
NuclearN lPowerPPlants
Pl tInterim regulation• Water and Milk: 300Bq/kg• Vegitables
V it bl (Spinach(S ih etc):t ) 2,000Bq/kg
2 000B /kSupporting data
• Water and Milk: 1L intake for a year = Absorbed dose 20.2mGy(20mSv): <<cancer risk• Vegitables: Occasional intake
Surface radiation may be minimized by washing

These regulation has wide range of safety(much less than the lower limits of possible harmful dose)

The radiation is gradually decreasing(half life of I-131: 8 days)
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Summary•

The biological effects from this accident are very small for
mostt off us, exceptt thosethworking
ki ini restrictedt i t d areas(Fukushima power plants) at present.

•People in Hokkaido are quite safe with no radiation effect.

•Those escaped
Thd fromf
theth restrictedt i t d areas aroundd Fukushima
F k hinuclear power plants are also safe based on the results ofradiation monitoring over 50,000 people.

•The water, milk, and, food (vegitables and fishes) are also
safe under the government control.
control (The safely range ismuch less than the lower limits of possible harmful dose)

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Asahi Shinbun (Newspaper) Apr 12, 2011