Human Health and the
Biological Effects of Tritium in
Drinking Water
Douglas Boreham, Professor
McMaster University
Medica...
McMaster and Bruce Power
McMaster
AECL - CRL
Bruce B
Nuclear 101
Antoniazzi August 26,
2010
Basic CANDU OperationBasic CANDU Operation
• CANDU’s (CANadian Deuterium Uranium)
reactors use ...
Bruce Power 2009 Tritiumin Drinking Water
0.0
10.0
20.0
30.0
40.0
50.0
JanuaryFebruaryM
arch
April
M
ay
June
JulyAugust
Se...
Radiological Environmental
Monitoring
Tritiumin Drinking Water 2001-2009
0
5
10
15
20
25
30
35
40
45
50
January
February
M...
Recommendations
1. The Ontario Drinking Water Quality Standard for
Tritium should be revised to 20 Bq/L,
recognizing that:...
Antoniazzi August 26, 2010
Tritium, Heavy Water & CANDU
•Heavy water is used in the CANDU reactor
to control the nuclear r...
Deuterium Heavy Water and Tritium
Biological Half-Life Heavy Water
(D2O)
First Human Isotope
Tracer Experiment
(Tea Cup)
• 55 samples of urine and
other exc...
What is Bq/L (beta Emitters)
Tritium – Naturally 1-7 Bq/L
Potassium – 40 100-150 Bq/L
Water
Banana Smoothie
Carbon – 14 20...
Nuclide Total Mass of Nuclide Total Activity of Nuclide
Found in the Body Found in Body
Uranium 90 µg 1.1 Bq
Thorium 30 µg...
Radiation Dose
(2L per day x 365 days)
70,000 Bq/L = 1.0 mSv/a (Australia)
7,000 Bq/L = 0.1 mSv (Canada)
20 Bq/L = 0.0003 ...
What is Bq/L and Dose
70,000 Bq/L = 1.0 mSv per year = 1 mammogram
(2.0 mSv/yr – 200+ mSv is natural)
7000 Bq/L = 0.1 mSv ...
Radiation Tracks and Biological
Cells
At low dose the density of
radiation ‘tracks’ is low; some
cells are ‘hit’ and other...
The average dose per hit for a spherical volume 5µm in
diameter (approximate diameter of a mammalian cell
nucleus) from th...
Sleeping next to someone most nights of a year results in a radiation
dose about the same as that from an X-ray of your ha...
Same Dose Rate per Hour
(0.004 mSv/h)
=
1 metre 30,000 ft
60 hours = 0.24 mSv
Dose (mSv/yr)
0.0001 0.0004 0.1 1.0 10 500
Public radiation dose
Frank Saunders
French Academy Vs BEIR
Pacific Basin Nuclear Conference Position
Statement
Pacific Basin Nuclear Conference Position
Statement
•The risk of cancer generation is trivial or zero
up to more than a hu...
In Press: Radiation Protection Dosimetry
2010.
“Recent radiological studies in the low dose region demonstrate that
the me...
Implications for
Radiation Protection
At low dose
• Dose is NOT a surrogate for risk
• Dose (risk) is NOT additive and ris...
• The assumptions of the LNT hypothesis
and radiation protection practices are
not compatible with the observations in
vit...
Human health and the biological effects of tritium in drinking water  boreham
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Human health and the biological effects of tritium in drinking water boreham

  1. 1. Human Health and the Biological Effects of Tritium in Drinking Water Douglas Boreham, Professor McMaster University Medical Physics and Applied Radiation Sciences, Hamilton, Ontario, Canada. Principal Scientist, Bruce Power.
  2. 2. McMaster and Bruce Power McMaster AECL - CRL
  3. 3. Bruce B
  4. 4. Nuclear 101
  5. 5. Antoniazzi August 26, 2010 Basic CANDU OperationBasic CANDU Operation • CANDU’s (CANadian Deuterium Uranium) reactors use heavy water in the primary heat transport system (the coolant) and as a moderator of the nuclear reaction http://en.wikipedia.org/wiki/CANDU_reactor
  6. 6. Bruce Power 2009 Tritiumin Drinking Water 0.0 10.0 20.0 30.0 40.0 50.0 JanuaryFebruaryM arch April M ay June JulyAugust Septem berOctober Novem ber Decem ber Month Bq/L Bruce A Bruce B proposed 20 Bq/L Approx. Minimum Detection Environmental Monitoring
  7. 7. Radiological Environmental Monitoring Tritiumin Drinking Water 2001-2009 0 5 10 15 20 25 30 35 40 45 50 January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June July August September October November December 2001 2002 2003 2004 2005 2006 2007 2008 2009 Bq/L Background + Past Emissions Kincardine Port Elgin Southampton Background
  8. 8. Recommendations 1. The Ontario Drinking Water Quality Standard for Tritium should be revised to 20 Bq/L, recognizing that: • 20 Bq/L relates to health effects from long term, chronic exposure over a life time of exposure of 70 years; • 20 Bq/L is within the range of variations considered by the council (7 Bq/L to 109 Bq/L), for a 10-6 risk level; and • 20 Bq/L, based on a running annual average, is achievable in drinking water, without significant cost to the nuclear power industry, according to the Canadian Nuclear Association.
  9. 9. Antoniazzi August 26, 2010 Tritium, Heavy Water & CANDU •Heavy water is used in the CANDU reactor to control the nuclear reaction using natural uranium •Heavy water in the presence of the neutrons (capture by deuterium atom) continuously generates tritium (DTO). •Production rate ~2 x 1012 Bq/MW(e).a in the heat transport (PHT) system and ~7.2 x 1013 Bq/MW(e) in the Moderator (~97% generated in the moderator)
  10. 10. Deuterium Heavy Water and Tritium
  11. 11. Biological Half-Life Heavy Water (D2O) First Human Isotope Tracer Experiment (Tea Cup) • 55 samples of urine and other excreta • 1000 distillation operations Conclusion :body’s water turned over every 9 days Hevesy, G. and Hofer, E. Elimination of water from the human body. Nature 134: 879; 1934
  12. 12. What is Bq/L (beta Emitters) Tritium – Naturally 1-7 Bq/L Potassium – 40 100-150 Bq/L Water Banana Smoothie Carbon – 14 200-300 Bq/L Veggie Shake
  13. 13. Nuclide Total Mass of Nuclide Total Activity of Nuclide Found in the Body Found in Body Uranium 90 µg 1.1 Bq Thorium 30 µg 0.11 Bq Potassium-40 17 mg 44,000 Bq Radium 31 pg 1.1 Bq Carbon-14 95 µg 20,000 Bq Tritium 0.06 pg 23 Bq Polonium 0.2 pg 37 Bq Natural Radioactivity in Your Body Bq is a decay per second Uranium alpha particles 90,000 per day Tritium beta particles 2,000,000 per day Potassium beta particles 3 billion/day
  14. 14. Radiation Dose (2L per day x 365 days) 70,000 Bq/L = 1.0 mSv/a (Australia) 7,000 Bq/L = 0.1 mSv (Canada) 20 Bq/L = 0.0003 mSv/a (Ontario)
  15. 15. What is Bq/L and Dose 70,000 Bq/L = 1.0 mSv per year = 1 mammogram (2.0 mSv/yr – 200+ mSv is natural) 7000 Bq/L = 0.1 mSv per year = Standard X-ray 70 Bq/L = 0.001 mSv = Human (7000 Bq) 20 Bq/L = 0.0003 mSv = 3 minutes flying/change in 6 feet of elevation.
  16. 16. Radiation Tracks and Biological Cells At low dose the density of radiation ‘tracks’ is low; some cells are ‘hit’ and others are not. The radiation energy deposited in any individual cell is a random variable and covers a range that depends on the radiation type.
  17. 17. The average dose per hit for a spherical volume 5µm in diameter (approximate diameter of a mammalian cell nucleus) from the experiments of Ellet and Braby δ = 11.2 mGy For a tritium concentration of 20Bq/L the committed dose is 0.286 µGy and therefore the fraction of exposed cells with hit nuclei is:- 2.5 per 100,000 cells What are the Event Frequencies for Tritium F1 = [1-e-D/δ ]
  18. 18. Sleeping next to someone most nights of a year results in a radiation dose about the same as that from an X-ray of your hand. 0.02 mSv/a = Potassium-40 X-ray
  19. 19. Same Dose Rate per Hour (0.004 mSv/h) = 1 metre 30,000 ft 60 hours = 0.24 mSv
  20. 20. Dose (mSv/yr) 0.0001 0.0004 0.1 1.0 10 500
  21. 21. Public radiation dose Frank Saunders
  22. 22. French Academy Vs BEIR
  23. 23. Pacific Basin Nuclear Conference Position Statement
  24. 24. Pacific Basin Nuclear Conference Position Statement •The risk of cancer generation is trivial or zero up to more than a hundred times the average of natural background radiation. •There are adaptive responses to low levels of radiation exposure which reduce the effects of damage from all causes, including those from radiation, thus reducing risk to levels lower than those observed in the absences of the radiation exposure.
  25. 25. In Press: Radiation Protection Dosimetry 2010. “Recent radiological studies in the low dose region demonstrate that the mechanisms of action for many biological impacts are different than those seen in the high-dose region. When radiation is delivered at a low dose rate (i.e. over a longer period), it is much less effective in producing biological changes than when the same dose is delivered in a short period. Therefore, the risks due to low dose-rates effects may be over-estimated.”
  26. 26. Implications for Radiation Protection At low dose • Dose is NOT a surrogate for risk • Dose (risk) is NOT additive and risk can increase OR DECREASE • Risk per unit dose is NOT constant, dose thresholds exist, for overall risk and for each tissue (WT)
  27. 27. • The assumptions of the LNT hypothesis and radiation protection practices are not compatible with the observations in vitro or in vivo •• Human and environmental riskHuman and environmental risk assessments must consider real effectsassessments must consider real effects • A new approach to radiation protection at low doses is needed CONCLUSIONS At low doses

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