Tritium: are current health risks properly assessed?
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Transcript Tritium: are current health risks properly assessed?
Tritium’s health hazards:
why we should be concerned
Dr Ian Fairlie
Consultant on Radiation in the Environment
London
United Kingdom
Tritium releases
from reactor types
TBq per GW(e) yr
Heavy Water Reactor
Pressurised Water Reactor
Boiling Water Reactor
670
20
2
data source: UNSCEAR (2000)
Tritium Release Limits
TBq/year
(combined liquid and gaseous)
COUNTRY
Nuclear Power Station
TBq /year
Canada
Darlington
Belgium
Doel
100
Germany
All sites
70
846,000
Netherlands Borssele
30
UK
8
Sizewell
Key Problem
official dose per Bq for tritium is very low
therefore the estimated tritium “doses”
are usually tiny
but the huge tritium releases mean if
tritium’s dose estimates are wrong, the
health consequences could be serious
Tritium doses from inhalation
(EU RODOS Model) in mSv
8th Meeting of the IAEA (EMRAS) Tritium & C-14 Working Group
May 30 - June 1, 2007 - Bucharest, Romania (http://www.nipne.ro/emras/)
Tritium doses from ingestion
(EU RODOS Model) in mSv
8th Meeting of the IAEA (EMRAS) Tritium & C-14 Working Group
May 30 - June 1, 2007 - Bucharest, Romania (http://www.nipne.ro/emras/)
Estimated tritium levels in cow’s milk
(EU RODOS Model) HTO Bq/kg
8th Meeting of the IAEA (EMRAS) Tritium & C-14 Working Group
May 30 - June 1, 2007 - Bucharest, Romania (http://www.nipne.ro/emras/)
Estimated tritium levels in cow’s milk
(EU RODOS Model) OBT Bq/kg
8th Meeting of the IAEA (EMRAS) Tritium & C-14 Working Group
May 30 - June 1, 2007 - Bucharest, Romania (http://www.nipne.ro/emras/)
Tritium concentrations in air
near Canadian reactors Bq/m3
from Osborne RV (2002) Tritium in the Canadian Environment: Levels and Health Effects. Report RSP 0153-1. Prepared for the CNSC.
Tritium concentrations in food near
Canadian reactors - Bq/l
from Osborne RV (2002) Tritium in the Canadian Environment: Levels and Health Effects. Report RSP 0153-1. Prepared for the CNSC.
Estimated annual tritium intakes
near a Canadian nuclear power
station
after Osborne, 2002; annual intake values from Health Canada (1994)
Tritium source Intake
per Tritium
Bq/year
annum
concentration
Water in food
425 litres
~2,000 Bq/L
850,000
Air Inhalation
8,400 m3
10 Bq/m3
84,000
Water in drinks
550 litres
100 Bq/L
55,000
10 Bq/m3
33,000
~700 Bq/kg
~53,000
Skin absorption
OBT in food
TOTAL
60% of
inhalation
75 kg
~1,000,000
Controversy over Tritium’s “Doses”
tritium’s dose coefficient is the smallest
(by far) of all radionuclides
often described as a “weak” emitter, but
2-3 times more hazardous than most
gamma/beta emitters
major misconceptions present
3 main problems
Reports discussing the
Controversy Over Tritium Doses
1.
2.
3.
4.
5.
AGIR HPA Report (2007) Review of Risks from Tritium
Melintescu A, Galeriu D and Takeda H (2007)
Reassessment Of Tritium Dose Coefficients For The
General Public. Radiat Protect Dosim June 2007, pp. 1–5
Fairlie I (2007) RBE and wR values of Auger emitters and
low-range beta emitters with particular reference to
tritium. Journal of Radiol Prot. Vol 27 pp 157-168
US EPA draft White Paper. Modifying EPA Radiation Risk
Models Based on BEIR VII. August 1 2006
Makhijani A, Smith B, and Thorne MC (2006) Science for
the Vulnerable: Setting Radiation and Multiple Exposure
Environmental Health Standards to Protect Those Most at
Risk. See chapter 7 on tritium.
http://www.ieer.org/campaign/report.pdf
What’s Wrong?
1.
Wrong radiation weighting factor (wR)
2.
Wrong metabolic/dosimetric models
3.
Refusal to acknowledge its hazards
1. Radiation “weighting” (wR) is
Wrong
An important issue
UK (AGIR) says wR x 2
US EPA says wR x 2.5
but ICRP says it won’t change (because of
French obsession with fusion research ITER at Cadarache)
Observed RBE values
from Fairlie I (2007) RBE and wR values of Auger emitters and low-range beta emitters with particular
reference to tritium. Journal of Radiological Protection. Vol 27 pp 157-168
Distribution of RBEs for HTO/gamma
4
3.5
RBE
3
2.5
2
1.5
1
0.5
0
1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Experiment
2. Tritium Models are Poor
No recognition of tritium levels building up
to high levels from chronic exposures
No consideration of heterogenous
distribution of tritium, especially OBT
OBT badly modelled: experimental animal
and human data ignored
3. Unusual Tritium Properties
unrecognised
Extreme mobility in environment (as H2O)
Rapid uptake in biota, ie humans
60% of atoms in humans are H atoms
High atomic exchangeability
Ability to bind with organic materials
5% in metabolic reactions each day
Short-range beta particle, so damage
depends on location in cell, eg near DNA?
Overall Result:
Tritium’s dose coefficient should be
increased x 20
1.
2.
3.
Weighting Factor = x 2.5
Correct Models
=x4
Hazardous Nature = x 2
Therefore need to increase tritium doses by
2.5 x 4 x 2 = 20
Precautionary Principle
Ie
- err on the side of caution
Do not use scientific uncertainty
as excuse for inactivity
where there is some evidence of
harm – act to reduce or avoid it
or warn about it
Main Conclusions
high tritium concentrations in air
moisture, food, water near NPPs
therefore high tritium exposures to
nearby residents
likely cancers, leukemias (but hard to
pick up)
Main Recommendations
1.
2.
3.
4.
5.
Use Precautionary Principle
Set up permanent health committees on
tritium with NGO reps
Further epidemiology studies
Advise local people
Tighten tritium limits
Health Recommendations
protect the vulnerable and most exposed
pregnant women, nursing mothers, and
children (under 4) should not live within
10 km
people within 5 km should not consume
food from their gardens, beehives,
orchards, and wild foods growing nearby
Globe and Mail: June 12 2007
Useful References
Canadian Nuclear Safety Commission (2001) Tritium in the Canadian Environment: Levels and Health Effects. Report RSP-0153-1. Prepared for the
Canadian Nuclear Safety Commission under CNSC contract no. 87055-01-0184 by Ranasara Consultants and Richard Osborne.
CERRIE (2004) Report of the UK Government’s Committee Examining the Radiation Risks of Internal Emitters. www.cerrie.org
Energy Washington Week (2007) “EPA Tritium Risk Plan May Force Tighter Nuclear Plant Controls”, Vol. 4, No. 25, 20 June 2007.
Fairlie I (2007) RBE and wR values of Auger emitters and low-range beta emitters with particular reference to tritium. Journal of Radiological Protection.
Vol 27 pp 157-168. (2007) http://www.iop.org/EJ/abstract/0952-4746/27/2/003/
Greenpeace Canada. (2007) Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities.
http://www.greenpeace.org/raw/content/canada/en/documents-and-links/publications/tritium-hazard-report-pollu.pdf
Health Canada (1994) Human Health Risk Assessment for Priority Substances. Ottawa, Canada: Ministry of Supply and Services Canada.
http://www.iop.org/EJ/abstract/0952-4746/27/2/003/
Hey E (1995) The Precautionary Principle. Where Does It Come From And Where Might It Lead In The Case Of Radioactive Releases To The
Environment. In Proceedings of an International Atomic Energy Agency Symposium on The Environmental Impact of Radioactive Releases. Vienna, May
1995. IAEA-SM-339/195.
Kirchner G (1990) A New Hazard Index for the Determination of Risk Potentials of Radioactive Waste. J of Environmental Radioactivity, 11, pp 71-95.
Makhijani A, Smith B, and Thorne MC (2006) Science for the Vulnerable: Setting Radiation and Multiple Exposure Environmental Health Standards to
Protect Those Most at Risk. See chapter 7 on tritium. http://www.ieer.org/campaign/report.pdf
OECD/NEA (1980) Radiological Significance and Management of Tritium, Carbon-14, Krypton-85, and Iodine-129 Arising from the Nuclear Fuel Cycle
Nuclear Energy Agency of OECD, Paris.
Ontario Drinking Water Advisory Council (2009) Report and Advice on the Ontario Drinking Water Quality Standard for Tritium.
http://www.odwac.gov.on.ca/reports/minister_reports.htm
Ontario Government’s Select Committee on Ontario Hydro Affairs: Hearings on The Safety of Ontario's Nuclear Reactors. Tuesday, July 10, 1979.
http://www.ccnr.org/tritium_2.html#scoha
Osborne RV (1966) Absorption of tritiated water vapour by people. Health Phys 12:1527-1537
Osborne RV (2002) Tritium in the Canadian Environment: Levels and Health Effects. Report RSP-0153-1. Prepared for the Canadian Nuclear Safety
Commission.
Paunescu N, Cotarlea M, Galeriu D, Margineanu R and Mocanu N (1999) Evaluation of environmental tritium levels in pre-operational period of
Cernavoda CANDU Nuclear Power Plant. Journal of Radioanalytical and Nuclear Chemistry Volume 239, Number 3. March 1999. pages 465-470.
Porter Commission (1980) The Report of the Royal Commission on Electric Power Planning. Volume 6. Environmental and Health Implications of Electric
Energy in Ontario. p 85. Ontario Government, Toronto, Ontario, Canada.
Societatea Nationala “Nuclearelectrica” S.A. CNA Cernavoda. (2005) Raport di Mediu.
Song MJ, Son SH and Jang CH (1995) Tritium Inventory Prediction in a Candu Plant. Water Management Vol 15 No 8 pp 593-598..
UNSCEAR (2000) Sources and Effects of Ionizing Radiation. United Nations Scientific Committee on the Effects of Atomic Radiation. New York NY USA.
Varlam C et al (2005) The use of tritiated wastewater from NPP Cernavoda to estimate maximum soluble pollutants on the Danube - Black Sea channel.
Fusion Science and Technology, vol. 48, no 1., pp. 716-719.
Workman WJ, Trivedi A and Cornett RJ (1998) Tritium Concentrations inside the Homes of Occupationally Exposed Workers: Dosimetric Implications.
Health Physics Vol 75 No 1, pp 56-59.