Low-Dose Radiation and Risk

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Low-Dose Radiation and Risk
• A Perspective
• Philippe Duport
• Centre for Low-Dose Radiation Research
• Institute of the Environment
• University of Ottawa

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Centre for Low-Dose ResearchInstitute of the
EnvironmentUniversity of OttawaFunding
US-DOE, Électricité de France, Central Research
Institute of Electric Power Industry,
MDS-Nordion, CNS, CANDU
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Started in 1997
• Main objective to assemble and analyze,
  globally, all published data on low dose
  radiation carcinogenesis in lab mammals
• Database of gt 150 000 animals
• http//www.ie.uottawa.ca

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• What is ionizing radiation?
• Radiation in the environment and in our body
• Low-dose radiation and cancer Is there a risk?
• If yes, how big is it?
• Animal experiments
• Human data
• Natural radiation levels and cancer
• Radiation workers
• Medical irradiation and cancer
• The Healthy Worker Effect
• Conclusions

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Units Activity
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Historical
• Curie (Ci) 37 000 000 000 disintegrations per
  second
• Modern
• Becquerel (Bq) 1 disintegration per second

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Units - Dose
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Complex system (absorbed, equivalent, effective
  dose)
• Historical Rem (Roentgen equivalent man)
• Modern Sievert
• Scale of effects (acute exposure)

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Cosmic radiationExposure at Different Elevations
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
1 mrem/year 200 feet of altitude 4 mrem/year
800 feet 500 mrem/year some isolated
populations (10 mrems 0.1 mSv)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Annual dose from internal radiation 0.2 mSv
constant
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Country averages extreme cases not shown (e.g.
Kerala (India), Ramsar (Iran)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Unsuspected sources of radiation
• Uranium, thorium in coal, released from U.S.
  coal-fired plants in 1982
• 800 tons of Uranium
• 1970 tons of Thorium
• Radon decay products (mostly Po-210) accumulated
  on the ground, from Rn released from soil
• 40 tons equivalent-Pu-239 per year on the ground
  of the territory of Ontario

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Unsuspected sources of radiation
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• 10 000 Bq/m3 of Po-210 and PB-210 in
• clean mountain water from Mont Blanc
  (Alps)
• 20 mSv per 1000 litres consumed (adults)
• 35 mSv per 1000 litres consumed (chidren)

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Annual dose limit for the public
Evacuation In case of incident
Annual dose limit for radiation workers
Action levels (Public)
Natural background radiation Radiation levels
(average annual doses) from natural and man-made
sources (adapted from Jaworowski Z, Radiation
Risks and Ethics, Physics Today, Sept. 1999
Graph expended by Rockwell T. from UNSCEAR
figures)
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Background Cancer
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Over 30 of us will develop cancer
• About 25 will die of cancer
• Cancer risk is variable as a function of
• Genetic Background
• Environmental Exposures
• Diet - Lifestyle

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
                                        Figure
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Radiation effect on DNA
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Number of Events Occurring Daily in Each Cell of
the Body 
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Possible outcomes of a cellular radiation
exposure in a normal cell (From R. Mitchel,
AECL)
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Radiation-induced resistance
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Extension of latency period in mice developing
acute myeloid leukemia (R. Mitchel, AECL, IRPA
10, 2000)
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Is the risk proportional to dose ??(Linear or
not ??)
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Threshold
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
200 mGy
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Probability that protective effect does not exist
in that experiment less than 1 in 1 millions
million
Figure 2. Relative risk for all cancers in mice
exposed to gamma radiation (reticular tissue and
solid cancers) (Ref Ullrich Storer, Radiat.
Res. 80(2)303-342, 1979)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Human data
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Howe 1996 paper
Miller 1989 paper
LOW-DOSE LINEARITY THE RULE OR THE
EXCEPTION? Figure 6. The Canadian Tuberculosis
Fluoroscopy Study of Miller et. al. A graphic
plot by E.W. Webster of the study data showing
the authors' "best fit" linear model and
linear-quadratic model relationships. (Martha
Heitzmann1 and Richard Wilson, BELLE Newsletter
Vol 6, No. 1, March 1997) Graph shown by E.W.
Webster at Lauriston Taylor lecture, NCRP 121,
1995
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Cancer incidence and mortality after treatment of
hyperthyroidism(Franklin et al. The Lancet 353
2111-2115, 1999)
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
How to modify the perception of radiation risk
Bone sarcoma in Radium dial painters (Linear
scale)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

•    

Bone dose
Bone sarcoma in Radium dial painters (Log scale)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Linear scale
Log scale
Bone sarcoma in Radium dial painters
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Probable thresholds for alpha emitters
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Osteosarcoma
• In dial painters D 8 Gy (160 Sv)
• In Pu-exposed Mayak workers - D 2 Gy

• Liver cancer
• in Thorotrast patients - D 2 Gy (40 Sv)
• in Pu-exposed Mayak workers

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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
SMR Standardized Mortality Ratio no. observed
/ no. expected
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Canadian National Dose registry StudyAshmore et
al. Am. J. Epid. 148(6) 564-574 (1998)Sont et
al. Am. J. Epid. 148(6) 564-574 (2001)
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Radon map USA Blue low risk Yellow Moderate
risk Pink High risk
Cancer incidence map
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Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)
Action level (Bq)m3)
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Medical uses of low-dose radiation
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Treatment of rheumatisms and asthma in radon spas
  (covered by national medical insurance in Germany
  and Austria)
• Clinical tests show that low-dose total or
  half-body irradiation at doses well below cell
  killing - contribute to curing cancer and
  preventing metastases (Japan, France)

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Conclusions - 1
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Ionizing radiation is part of life.
• Sources of ionizing radiation are naturally
  everywhere, in food, air, water and our body.
• Life appeared and evolved in a radioactive
  environment.
• At environmental levels, there is no evidence of
  increased risk with increased dose, even when
  annual doses exceed current dose limits for
  radiation workers

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Conclusions - 2
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• In fact, there are indications of decreased risk
  of cancer and non-malignant diseases at doses and
  dose rates well above current regulatory limits
  for the public and the workers.
• Populations in high background areas tend to have
  less cancers than those in low background areas.
• Low dose radiation is used in medicine radon
  spas, cancer treatment and prevention.

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Question
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Are we doing more good than harm when radiation
  exposures are reduced to levels as low as
  reasonably achievable ?
• or
• Is there any public health benefit at all in
  reducing radiation doses as much as possible?

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Position of the French Academy of Medicine (Nov.
2001)
Ottawa U I. E. - International Centre for
Low-Dose Radiation Research (Jan 2002)

• Conclusion 3 denounces the utilization of the
  linear no-threshold (LNT) relation to estimate
  the effect of doses lower than a few mSv
  (equivalent to variations of natural radiation in
  France)
• Conclusion 5 recommends the introduction of
  the ADIR (Annual Dose of Incorporated
  Radioactivity ( 0.2 mSv) resulting from
  homogeneous exposure of the human body to natural
  potassium-40 and carbon-14), as this dose
  equivalent is almost constant whatever the size
  of the individual and the geographic region.

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http//www.epa.gov/iaq/radon/images/zonemap2.jpg