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. McMaster and Bruce Power
McMaster
AECL - CRL

3. Bruce B

4. Nuclear 101

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. Bruce Power 2009 Tritiumin Drinking Water
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Bruce A
Bruce B
proposed 20 Bq/L
Approx. Minimum Detection
Environmental Monitoring

7. Radiological Environmental
Monitoring
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2001 2002 2003 2004 2005 2006 2007 2008 2009
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Background + Past Emissions Kincardine Port Elgin Southampton Background

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. 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. Deuterium Heavy Water and Tritium

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. 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. 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. 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. 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. 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. 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. 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

20. Same Dose Rate per Hour
(0.004 mSv/h)
=
1 metre 30,000 ft
60 hours = 0.24 mSv

21. Dose (mSv/yr)
0.0001 0.0004 0.1 1.0 10 500

22. Public radiation dose
Frank Saunders

23. French Academy Vs BEIR

24. Pacific Basin Nuclear Conference Position
Statement

25. 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.

26. 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.”

27. 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)

28. • 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