Report and Advice on the
Ontario Drinking Water
Quality Standard for
Tritium
Prepared for the Honourable John Gerretsen
Ontario Minister of the Environment

By the Ontario Drinking Water Advisory Council

May 21, 2009

The Ontario Drinking Water Advisory Council,
known formally as the Advisory Council on
Drinking Water Quality and Testing Standards, isan Agency of the Government of Ontario

www.odwac.gov.on.ca

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Table of Contents
1.0
Executive Summary and Conclusion(s):............................................................................. 3
2.0
Introduction......................................................................................................................... 7
Part I................................................................................................................................................ 8
1.0
Background ..................................................................................................................... 8
2.0
Tritium .......................................................................................................................... 10
3.0
Monitoring and Reporting............................................................................................. 22
4.0
Health and Risk............................................................................................................. 24
4.1
Reviews and Reports ................................................................................................. 24
4.2
Risk Level .................................................................................................................. 27
5.0
Overview of Approaches by Other Jurisdictions .......................................................... 29
6.0
Impacts and Cost implications ...................................................................................... 32
7.0
Stakeholder and Experts Meetings................................................................................ 33
8.0
Public Consultation....................................................................................................... 33
Part II ............................................................................................................................................ 37
1.0
Conclusions................................................................................................................... 37
1.1
Background and Sources .......................................................................................... 37
1.2
Health Risks .............................................................................................................. 38
1.3
Monitoring and Reporting ........................................................................................ 39
1.4
Cost Issues ................................................................................................................ 39
1.5
Corrective Actions .................................................................................................... 40
2.0
Developing the Standard............................................................................................... 40
2.1
Numerical Variations................................................................................................ 41
2.2
Reaching Consensus on a Numerical Standard........................................................ 43
3.0
Recommendations......................................................................................................... 45
Acronyms...................................................................................................................................... 46
References..................................................................................................................................... 48
Appendices.................................................................................................................................... 55

Page 1 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Page 2 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

1.0 Executive Summary and Conclusion(s):As part of its role, the Ontario Drinking Water Advisory Council provides advice on drinking
water quality standards as a result of direct requests by the Minister of the Environment, and canalso undertake consultations to facilitate transparency in process and provide for stakeholder andpublic participation. The Council’s advice is directed to the Minister.
In the case of tritium, the Minister formally requested the Council to provide advice on the
Ontario Drinking Water Quality Standard on February 21, 2007, as a result of the issue being
raised by the Medical Officer of Health for the City of Toronto. As part of its review, theCouncil was requested to take into consideration the 1994 recommendations on tritium made by
the former Advisory Committee on Environmental Standards (ACES) in their report entitled: “AStandard for Tritium: A recommendation to the Minister of the Environment and Energy”.
On June 12, 2007, the Minister made an additional request for the Council to also take into
consideration a Greenpeace Canada report, authored by Dr. Ian Fairlie entitled “Tritium Hazards
Report: Pollution and Radiation Risks from Canadian Nuclear Facilities”.
In undertaking its review, the Council established a working group comprised of members withknowledge of the issue and experience in radionuclide risk and regulation to assist the Council as
a whole. A multi-step approach was developed including:






obtaining and reviewing all pertinent documentation for review;
undertaking an inter-jurisdictional comparison;
meeting with key stakeholder groups and individuals;
holding a public consultation to hear directly from interested parties; anddeveloping recommendations for the full Council’s consensus.

The preliminary conclusions, reached by the working group and presented to the full Council for
discussion and subsequent Council consensus on a proposed Standard, as well as a number ofmeasures related to implementation, include the following:

there is a natural background level of tritium in water in Ontario, in the range of 2 to 3 Bq/L;
any levels above this range imply man-made sources;in setting a drinking water Standard in Ontario we are in fact saying that it is acceptable or‘safe’ to allow that water to be consumed each day over a lifetime of 70 years;

the Council agrees with the conclusions of the BEIR VII report that there is linear doseresponse relationship and no threshold for the induction of cancers by radionuclides;

Page 3 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009


the target derived risk level should be 1 in a million or 10-6 (meaning 1 new excess cancer
occurrence over existing background cancer rates in 1,000,000 people);the target derived risk level should be over a lifetime of exposure of 70 years, and based on
cancer incidences above background (occurrences) rather than mortality (deaths);

tritium is the most common point source radionuclide found in drinking water in Ontario andrepresents an on-going, active source of radioactivity above background levels, resulting inlifetime exposure to large populations. As such, the approach taken for regulating tritium indrinking water should not imply that it is appropriate for other radiologically-regulated
activities or radionuclides;

current sampling programs conducted by The Ministry of Labour’s Nuclear Reactor
Surveillance Program, The Ministry of the Environment’s Drinking Water Surveillance
Program, and the nuclear power industry should continue;urgent action to protect the public from more immediate exposure to tritium should be basedon monitoring and reporting discharges from their source; not the drinking water treatment
plant. As such, short-term exposure to drinking water that exceeds the Standard should not
trigger inappropriate responses by agencies or the public rather such exceedances should be
used to set in motion a series of corrective actions at the emission source of the tritium to theenvironment; and

all tritium data and information should be made available by the nuclear power industry andthe Ministry of Labour, to the public, the Ministry of the Environment, and local publichealth offices, as soon as practicably possible.

In an effort to arrive at a proposed Standard, several numerical variations that use the models ofother jurisdictions and authorities were evaluated and revised using the Council’s own
conclusions. The technical challenge was how to best utilize the available radiological researchand information to arrive at a risk as close to 1 in a million (10-6) as possible, while maintaining
practicability and achievability.
These variations resulted in a range for a possible proposed Standard of approximately 7 Bq/L to
109 Bq/L, but the Council concluded that these variations, based on current science and risk
assessment practices, would not lead to consensus on a single number.
Since the Council could not unequivocally select one variation over another, given that theuncertainties in the scientific methods do not confirm any one particular value over another fromwithin the range, the following question was considered:Page 4 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Taking into account all the research and documentation, meeting with experts,
stakeholders, and the general public, and Council deliberations, is there a tritiumStandard (value or level) that a reasonable and informed person would feel safe
drinking the water every day over a lifetime of 70 years at or below that
Standard?
To answer this question, the Council went back to address some of the basic principles or criteria
used by Health Canada for setting Canadian Drinking Water Quality Guidelines for nonthreshold chemical carcinogens.
This would mean that the maximum acceptable concentration should be established at a level
which represents an estimated lifetime (70 years) risk of cancer falling within the range that is
considered to be “essentially negligible” or as close to “essentially negligible” as reasonably
practicable. "Essentially negligible" risk is generally interpreted by most world-wide regulatory
bodies, including Health Canada, as a range of risk of between 10-5 and 10-6.
However, the Council concluded that the target derived risk level for tritium in drinking water in
Ontario should be 1 in a million or 10-6.
The next step was to determine what limit would be considered to be “reasonably practicable”.
To address this, the Council turned to two documents received as part of consultation process:

The Canadian Nuclear Association noted in a letter to the Council that 20 Bq/L on an annual
average basis is achievable in drinking water, without significant cost to the industry; and

The Toronto Medical Officer of Health noted in a letter to the Council that the concern withtritium is chronic exposure, and that an annual average of 20 Bq/L would not be exceeded if
Ontario Power Generation did not exceed its current discharge limit of 4,000 Bq/L.

Based on these two documents, the Council concluded that an Ontario Drinking Water Quality
Standard for tritium of 20 Bq/L, applied as a running annual average, would meet therequirements for an appropriate level of risk and public safety, while remaining practicable andachievable by the nuclear power industry.
The Council further noted that, in applying a test of practicability to this proposed Ontario
Drinking Water Quality Standard for tritium, it should not be necessary for the nuclear powerindustry to alter any of the applicable regulations for occupational or other radiological criteria.
Tritium is the most common point-source radionuclide found in drinking water in Ontario andrepresents an on-going, active source of radioactivity above background levels, capable of
exposing large populations to levels above background. As such, the approach taken forregulating tritium in drinking water should not imply that it is appropriate for otherradiologically-regulated activities or radionuclides.
Page 5 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
The Council made 6 recommendations in all, as follows:
1. The Ontario Drinking Water Quality Standard for tritium should be revised to 20 Bq/L,
recognizing that:

20 Bq/L relates to heath 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.

2. The Standard of 20 Bq/L should be applied as the running average of the preceding 52
weekly composite samples. This running annual average is consistent with the current
weekly sampling and reporting programs, and should also be used to generate monthly
averages and identify trends.
3. The current sampling and monitoring programs, as conducted by the Ministry of Labour andthe industry, are appropriate, and should continue. Sampling and reporting should only berequired for those drinking water treatment plants that are in the proximity of or under the
influence of sources of tritium. As well, the Ministry of the Environment should continue tomonitor tritium at drinking water systems as part of the Drinking Water Surveillance
Program (DWSP).
4. Monthly reports of weekly test results and running annual averages should be sent toregulatory bodies, local municipalities and health units, local public interest groups, andshould also be made available to the general public.
5. It is equally important to monitor trends in the monthly data and if there is an indication ofincreases (even if they are below the Standard), the province should require the discharger totake appropriate corrective actions, in collaboration with other appropriate authorities.
6. Monitoring and reporting at the point of discharge should be the focus for emergency
response in that monitoring at drinking water treatment plants is not an appropriate approach
for alerting authorities and the public of significant and / or elevated discharges of tritium.
The current program should be enhanced to require the dischargers to report monthly toregulatory authorities and other public bodies on the levels of tritium discharges andimmediately in each case where discharges exceed designated notification level(s).

Page 6 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

2.0 Introduction
The broad mandate of the Ontario Drinking Water Advisory Council (formally known as theAdvisory Council on Drinking Water Quality and Testing Standards) is to provide advice andmake recommendations to the Minister of the Environment (Minister) on drinking water quality
and testing standards, as well as other drinking water matters deemed appropriate.
As part of its role, the Council provides advice on drinking water quality standards as a result of
direct requests by the Minister, and can also undertake consultations to facilitate transparency inprocess and provide for stakeholder and public participation.
In the case of tritium, the Minister formally requested the Council to provide advice on the
Ontario Drinking Water Quality Standard, as detailed in the letter to the Chair dated February 21,
2007 (See Appendix 1). The Minister noted that the issue had been raised by the Medical Officer
of Health for the City of Toronto, in a letter dated September 27, 2006, which also referenced arelated City of Toronto Council Resolution adopted on June 27, 28 and 29, 2006 (See Appendix
2). As part of its review, the Council was requested to take into consideration the 1994
recommendations of tritium made by the former Advisory Committee on Environmental
Standards (ACES) in their report entitled: “A Standard for Tritium: A recommendation to the
Minister of the Environment and Energy” [ACES, 1994].
On June 12, 2007 the Minister made an additional request (See Appendix 3) for the Council toalso take into consideration a Greenpeace Canada report, authored by Dr. Ian Fairlie entitled“Tritium Hazards Report: Pollution and Radiation Risks from Canadian Nuclear Facilities”[Greenpeace, 2007].
In undertaking its review on tritium, the Council established a working group comprised ofmembers with knowledge of the issue and experience in radionuclide risk and regulation to assist
the Council as a whole. A multi-step approach was developed including: obtaining andreviewing all pertinent documentation for review; undertaking an inter-jurisdictional
comparison; meeting with key stakeholder groups and individuals; holding a public consultation
to hear directly from interested parties; and developing recommendations for the full Council’s
consensus.
The preliminary conclusions reached by the working group were presented to the full Council for
discussion and subsequent Council consensus on a proposed Standard, as well as a number ofmeasures related to implementation.
It should be noted that the Council reviewed many references during the course of its
deliberations on tritium. Many of the references are highlighted in this report, but for full details,
the original reference should be consulted. Furthermore, the Council has provided only an
abbreviated overview of the scientific background covering concepts related to radiation and has
highlighted only those necessary to this report.
Page 7 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009Part I
1.0

BackgroundThe current Ontario Drinking Water Quality Standard (ODWQS) for tritium is 7,000 becquerels
per litre (Bq/L). This is consistent with the current 1995 Canadian Drinking Water Quality
Guidelines for Radiological Characteristics [Health Canada, 1995a], and the revised Radiological
Characteristics of Drinking Water Document for Public Comment [Health Canada, 2006]. 7,000
Bq/L was originally proposed in a November 1993 report entitled: “Rationale Document for theDevelopment of an Interim Ontario Drinking Water Objective for Tritium” as prepared by the
Ontario Ministry of Environment and Energy (MOEE) [MOEE, 1993]. At that time, the Ontario
Drinking Water Objective (ODWO) was 40,000 Bq/L.
The Minister then requested the Advisory Committee on Environmental Standards (ACES) to
conduct a public consultation on the MOEE’s proposed interim Objective. In May 1994, ACES
issued its report to the Minister, recommending that the Objective be immediately set at 100
Bq/L and that this limit be further reduced to 20 Bq/L over 5 years, with a goal of further
reductions as tritium background levels decline [ACES, 1994].
The ACES report examined two different risk assessment frameworks used in the developmentof drinking water objectives: radiological and chemical. Since all radionuclides and somechemicals are recognized as carcinogens, ACES proposed that tritium should follow the samerisk assessment framework as chemical carcinogens. As such, it was recommended that theacceptable level of risk for tritium should be the same as the acceptable level of risk for chemical
carcinogens and their regulation. Reference should be made to the ACES report for full details.
As well, the two approaches for risk assessment will be addressed in Part I, Section 4.0 of thisreport.
In December 1994, the MOEE completed a report entitled “Economic Consequences of an
ODWO for Tritium [MOEE, 1994]. This report addressed the cost implications of six scenarios
for a new tritium Objective proposed by ACES, and concluded that there could be significant
cost implications to Ontario Hydro, if the proposed Objective was adopted, depending on thevalue chosen and the type and frequency of monitoring and reporting of results. It should also be
noted that when the ACES report was completed, the province did not have legally enforceable
Ontario Drinking Water Quality Standards, as they do now. Instead, drinking water Objectives
were used to guide municipalities in providing safe drinking water, but they could be madelegally enforceable by including them in Certificates of Approval.

Page 8 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
The Minister’s decision to set the ODWO at 7,000 Bq/L was transmitted by letter to Ontario
Hydro. No record of this letter was found. However, the letter is referenced in a response fromOntario Hydro to the Minister, as outlined below:
On December 9, 1994, the President of Ontario Hydro, Mr. O. A. Kupcis wrote to the Minister ofEnvironment and Energy endorsing the Objective of 7,000 Bq/L (See Appendix 4). Ontario
Hydro made an additional commitment that “concentrations of tritium in drinking water willremain less than 100 Bq/L on average”. The commitment was based on applying “the principlethat all exposures to radiation are kept As Low As Reasonably Achievable (ALARA)”, in
keeping with the operational practices employed by Ontario Hydro at is nuclear power plants.

Page 9 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

2.0

Tritium

What is tritium, and what are its properties?
This section of the report provides only a brief summary about tritium and its physical, chemical,
and radiological properties. Several of the references provide more complete details.
The common hydrogen atom has one proton and no neutrons. Two hydrogen atoms combinewith oxygen to form water (H2O). Tritium is a hydrogen atom that has incorporated into its
nucleus two neutrons (added to the existing proton). Although tritium can be a gas (HT), thetritium molecule is preferentially found as a component of the water molecule - tritiated water(HTO), because elemental tritium readily reacts with oxygen to form water, by replacing one of
the hydrogen atoms in the water molecule (See Diagram 1).
Tritiated water has the same physical properties as regular water. It is colorless, odourless, andbehaves the same as regular water in the environment. Tritium in water exchanges withhydrogen from other water molecules but can also become incorporated into complex organic
molecules, such as proteins inside and outside cells in the body.
As with all radionuclides, tritium is unstable. This instability is called radioactive decay. As it
decays, tritium emits ionizing radiation in the form of low energy Beta particles. Beta particles
have the same properties (mass and charge) as electrons, and have the greatest biological impact
at very short distances, as they can travel in the air for only a distance of a few feet. Throughthis process of radioactive decay, tritium (with a half-life of 4,500 days, or approximately 12
years) slowly breaks down into helium. This relatively short half-life (years vs. thousands ofyears) results in more frequent beta emissions from tritium than in a substance with a longer halflife.
In addition to radioactive half-life, there is a process known as biological half-life. This is thetime it takes for one half of a given substance to be eliminated from the body. Tritiated water(HTO) has a biological half-life of approximately 10 days. Organically bound tritium (OBT),with a biologic half-life of approximately 40 days, stays in the body longer by becoming part ofcomplex molecules. However, once tritium becomes incorporated into cellular structures,
molecules, or DNA, its biological half-life extends to almost a year.

Page 10 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Diagram 1: Tritiated Water Decay

What is radioactivity and how is it measured?
In simple terms, radioactivity is the spontaneous nuclear transformation of unstable atoms,
leading to the formation of new atoms, and the emission of radiation.
Radiation describes any process by which energy emitted by one body travels through a mediumor through space, ultimately to be absorbed by another body. It can be classified as ionizing or
non-ionizing radiation, depending on its effect on other atoms, molecules, or biological tissue.
The most common use of the word "radiation" refers to ionizing radiation, which has enoughenergy to ionize atoms or molecules. There are three principal types of ionizing radiation, listed
here in their relative order of severity, from low to high as follows: alpha, beta, and gamma.
Geiger counters and scintillation counters are capable of detecting radiation by directly
measuring the disintegration rate of ionizing radiation. The unit of measurement for ionizing
radiation is the becquerel (Bq), which is defined as the activity of a quantity of radioactive
material in which one nucleus decays per second. In terms of measuring ionizing radiation in
drinking water, the units are becquerels/litre (Bq/L), which can quantitatively described as thenumber of disintegrations taking place in a litre of water, per second.

Page 11 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
How does tritium get into the environment and into drinking water?
There are both natural and man-made sources of tritium.
When cosmic rays strike nitrogen in the upper atmosphere, tritium is naturally produced andreaches the earth’s surface via rainfall, causing elevated levels in both surface water and groundwater.
Tritium was also produced during above-ground nuclear weapons testing, causing elevated levels
in both surface water and ground water, on a global scale.
On a local scale, tritium is produced as a result of reactions that take place within nuclear
reactors using deuterium or “heavy water”. During these nuclear reactions, neutrons from theuranium fuel change some of the reactor’s heavy water into tritiated water. Tritium builds up in
the heavy water until it is physically removed at a Tritium Removal Facility (TRF), such as theone operated by OPG at Darlington, but it is also released into the environment with the heavy
water, as a result of leaks and spills. This is the predominant route by which tritium reaches
surface water, and subsequently drinking water (See Diagram 1).

Surface Water
Tritium levels from atmospheric nuclear weapons testing fallout appear to be continuously
declining from a peak of just under 25 Bq/L in the mid 1960’s to approximately 1 Bq/L in 2007.
The combination of the natural source and this source results in an overall surface water
background level of 2.13 Bq/L in Lake Huron [Bruce Power, 2008a], and 1.6 Bq/L in Lake
Ontario [OPG, 2008].
Tritium levels in surface water can also be influenced by precipitation and groundwater sources.
The median concentrations of tritium in surface water at sites adjacent to the Bruce, Darlington,
and Pickering reactor facilities for 2007 are shown below in Table 1 [MOL, 2008].
Table 1: 2007 Surface Water Monitoring Results
Surveillance Area
Bruce
Darlington
PickeringNumber of Samples
108
8*Minimum Detectable Concentration

Page 12 of 56

Tritium (Bq/L)
30
<5*
14

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
The average tritium concentrations in the Great Lakes from 1997-1998 are presented below inTable 2. The ascending levels of tritium in surface water are a result of discharges from nuclear
power plants [Greenpeace, 2007].
Table 2: Average Tritium Concentration (in Bq/L) in the Great Lakes in 1997-1998
Lake Superior
Lake Michigan
Lake Huron
Lake Erie
Lake Ontario

2
3
7
5.5
7.1

Tritium Discharges
Tritium is discharged into the natural environment through routine leaks of heavy water, but it
appears that there are no specific records of such small leaks. Both OPG and Bruce Power haveprograms in place to continue to reduce the frequency and volume of these leaks [OPG/Bruce
Power, 2006; OPG, 2008; Bruce Power, 2008a].
Notification Levels for Waterborne Tritium Emissions from OPG:
Tritium notification levels for waterborne emissions from OPG are summarized below in Table 3[OPG, 2007], and form part of the Coordination of the Response to a Liquid Emission at OPG
and Bruce Power [OPG/Bruce Power, 2006].
Table 3: Tritium Levels for Waterborne Emissions
Description
Derived Release Limit(CNSC licence – emission
limit)
Action Level(CNSC licence – reportinglevel)
Ontario Standard for Drinking
Water Quality for Tritium
OPG Abnormal Waterborne
Tritium Emission Notification
Level (notification provided toDurham Region, Toronto,
MOE and CNSC)

Level (total activity)
Pickering – 5.1 x 1017 Bq/year

Level (concentration)*
3.0 x 105 Bq/L

Darlington – 4.3 x 1015 Bq/year

1.6 x 105 Bq/L

Pickering – 4.1 x 1015 Bq/month

2.9 x 104 Bq/L

Darlington – 3.5 x 1016 Bq/month

1.5 x 104 Bq/Lna

7000 Bq/L (at WSP)na

4,000 Bq/L at Station
Discharge* Where the limit is specified in terms of activity, this is the equivalent concentration that would have to be
maintained all year long to reach the limit (with all cooling water pumps running).

Page 13 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
According to OPG, over the past 17 years, there have been 2 releases of tritium that exceeded the
4,000 Bq/L reporting requirement at OPG [OPG, 2007]. Both occurred at Pickering and bothwere the result of mechanical problems resulting in a heat exchanger leak. Table 4 below
summarizes information about those releases.
Table 4: OPG Tritium Release Event Data Summary
Data
Release date
Peak outfall concentration
Time to Peak Impact(at Ajax WSP)
Duration of elevated tritium(at Ajax WSP)
Peak concentration(at Ajax WSP)
Highest daily average
concentration (Ajax WSP)
Maximum calculated dosefrom event
CNSC dose limit
Natural background radiation
dose

Pickering Moderator Heat
Exchanger
August 2, 1992
3 x 106 Bq/L

Pickering Unit 4 Shutdown
Cooler Heat Exchanger
April 15, 1996
1.7 x 105 Bq/L

4 days (Aug 6, 1992)

30 hours

8 daysna

1,300 Bq/L

831 Bq/L

587 Bq/L

na

0.00012 mSv

0.00010 mSv

1 mSv/y

1 mSv/y2 mSv/y2 mSv/yPage 14 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Notification of Tritium Emissions from Bruce Power:
Tritium notification levels for waterborne emissions from Bruce Power are summarized below inTable 5, and also form part of the Coordination of the Response to a Liquid Emission at OPG
and Bruce Power [OPG/Bruce Power, 2006].
Table 5: Tritium notification levels for waterborne emissions from Bruce
SourceCoordination of the Response toa Liquid Emission at OPG and
Bruce Power [OPG/Bruce
Power, 2006]

Description
Initial notification from
Bruce Power

Bruce Power’s Derived Release
Limits and Environmental
Action Levels [Bruce Power,
2008b]
Notification/Action Protocols for
Abnormal Tritium Releases at
BNPD (Bruce Nuclear Power
Development [Bruce Power,
1996]

Derived Release Limit fortritium in water
Action Level for tritium
releases to water
Action Level 1
Action Level 2
Action Level 3

Notification Level
Tritium levels in the coolingwater outfall >30,000 Bq/L,
corresponding to approximately
2,000 Bq/L at the Port Elgin
water supply plant
2.27E+18 Bq/year
1.21E+16 Bq/month
Tritium in CCW Discharge>30,000 Bq/L and <50,000 Bq/L
Tritium in CCW Discharge>50,000 Bq/L and <90,000 Bq/L
Tritium in CCW Discharge>90,000 Bq/L

Bruce Power has noted that there has been “an increasing trend in tritium in drinking
water since 2004. This trend can be attributed to a number of activities at the Bruce
Power site including the return to service of Units 3 & 4, refurbishment activities
surrounding Units 1 & 2, a sample cooler heat exchanger leak at Bruce A in 2006 (leakhas been isolated and scheduled for repair in 2008) and a boiler tube leak at Bruce B in2007 (leak has been repaired).” [Bruce Power, 2008a].
Greenpeace Canada provided a list of discharges in their report [Greenpeace, 2007], stating that”“In addition to routine releases to surface waters, significant groundwater and lake contamination
has occurred at Canadian nuclear facilities in the past.
In 1979, tritium groundwater concentration reached 2.15 MBq/L following a release of 666
TBq at Pickering;
In August 1983, a pressure tube at Pickering-2 ruptured, dumping an unspecified amount of
coolant into the reactor building;
In September 1983, a leak of 222 TBq of tritium occurred from the Douglas Point reactor on
Lake Huron. The prevailing counter-clockwise circulation pattern in the lake carried thetritium plume northeast to Port Elgin, where drinking water levels reached 1,600 Bq/L during
a 2-day period;
Page 15 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009









In January 1990, a loss-of-coolant accident at Bruce-4 resulted in a 12,000 kg leak of heavy
water into Lake Huron;
In June 1991, following a leak from Chalk River Nuclear Laboratories into the Ottawa River,the tritium concentration in drinking water at Petawawa was about 400 Bq/L. At Ottawa (200km downstream), the tritium level was ~150 Bq/L;
In August 1992, a tube break at Pickering-1 caused the release of 2,300 TBq of tritium into
Lake Ontario. A nearby drinking water plant was shut down and elevated levels of tritium(up to 195 Bq/L) were found in Toronto drinking water;
In May 1994, Ontario Hydro found a tritium groundwater concentration of 0.7 MBq/L
following a leak at Pickering;
In December 1994, a valve failure at Pickering-2 led to 140 tonnes of heavy water being
discharged into Lake Ontario;
In May 1995, a valve failure at Bruce-5 caused a 25-tonne leak of radioactive heavy water;
In April 1996, a heavy water leak at Pickering-4 released 50 GBq of tritium into Lake
Ontario; tritium levels in local drinking water reached 100 times background levels; andIn July 1997, it was revealed that Ontario Hydro (the predecessor to OPG) had failed toreport tritium contamination of groundwater on the Pickering site for a period of 20 years.”

Drinking Water
Levels of tritium in drinking water are monitored by the nuclear industry and the Ontario
Ministry of Labour’s Nuclear Reactor Surveillance Program.
Reference can be made to the 2007 annual reports of Ontario Power Generation [OPG, 2008],
and Bruce Power [Bruce Power, 2008a]. Table 6 below presents a summary of the 2007 levelsof tritium found at drinking water treatment plants in Ontario [MOL, 2008].
Table 6: 2007 Drinking Water Monitoring - Tritium Analysis
Surveillance Area
Bruce
Darlington
Essex
OttawaTorontoToronto-West

Number of Samples
154
260
47
36
203
36

Page 16 of 56

Median Value (Bq/L)
8.9
7.1
4.9
6.7
6.3
5.9

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
In addition, Table 7 below summarizes 5 years (2003-2007) of tritium in drinking water resultsfrom the three surveillance areas that have adjacent nuclear power generation facilities [MOL,2008].
Table 7: 5-year Results – Tritium in Drinking Water

Year
2003
2004
2005
2006
2007

Bruce
Surveillance Area
# ofConcentration
Samples(Bq/L)
148
7.31
152
8.47
153
8.99
154
11.92
154
8.87

Darlington
Surveillance Area
# ofConcentration
Samples(Bq/L)
255
6.38
258
6.23
260
5.86
260
6.63
260
7.08

Pickering
Surveillance Area
# ofConcentration
Samples(Bq/L)
154
6.43
157
6.17
202
5.98
203
4.81
203
6.29

Concentrations of tritium at specific drinking water treatment plants for 2007 are presented
below in Table 8, according to the Ministry of Labour’s Radiation Protection Monitoring
Service.
Table 8: 2007 Tritium Concentrations at Drinking Water Treatment Plants (Bq/L)
Maximum

Median

14
10
14

7.2
7.0
6.9

16
13
16
14

6.5
6.8
7.9
7.0

44
28
22

16.1
5.0
5.5

5.9
12
12

7.3
7.6

Nuclear Facility: Pickering
Water Treatment Plant:
Ajax
HorganR.C. Harris
Nuclear Facility: Darlington
Water Treatment Plant:
Newcastle
Bowmanville
OshawaWhitbyNuclear Facility: Bruce
Water Treatment Plant:
Port Elgin
Southampton
Kincardine
Nuclear Facility: Chalk River
Water Treatment Plant:
Deep River
Pembroke
Petawawa

Page 17 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
The City of Ottawa performs independent tritium monitoring of its drinking water treatment
plant intakes, and the analyses are performed by Health Canada’s Radiation Protection Bureau
laboratory. Results for 2008 are seen below in Table 9.
Table 9: City of Ottawa Drinking Water Treatment Plant Tritium Concentrations (Bq/L)
2008
City of Ottawa
Water Treatment Plant:

Britannia
Lemieux

Maximum

Average

22.8
11.5

5.2
5.0

Groundwater
Monitoring records show that precipitation in the proximity of nuclear facilities contains elevatedlevels of tritium resulting in elevated tritium concentrations in groundwater. In the Darlington
and Pickering survey areas, well levels ranged from 23.5 Bq/L to 86.1 Bq/L in 2007, while in the
Bruce survey area, well levels ranged from less than 6 Bq/L to over 70 Bq/L in 2007 [OPG,
2008; Bruce Power, 2008a].
Also, in the vicinity of SRB Technologies in Pembroke, a well used for drinking water at abusiness showed a concentration of 1,293 Bq/L in December of 2008 [SRB, 2009].

Page 18 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
ROLES AND RESPONSILITIESThe following summarizes the roles and responsibilities of various agencies and organizations
with respect to tritium and drinking water:
Federal Government:
Canadian Nuclear Safety Commission (CNSC):The CNSC regulates nuclear fuel production and power generation in Canada. Licensees andorganizations applying for licences are subject to many rules and regulations, including Derived
Release Limits (DRLs), which represent release rates of all radionuclides from a facility, that
correspond to critical group exposure at the public dose limit of 1 mSv per year.
Health Canada (HC):
Health Canada’s mandate is to reduce the health and safety risks associated with different typesof substances, and radiation by:







conducting research into the biological effects of environmental and occupational radiation;
developing better methods for internal radiation dosimetry and its measurement;
providing radiation safety inspections of federally regulated facilities containing radiationemitting devices, the devices themselves, as well as training on the proper operation of thedevices;developing regulations, guidelines, standards and safety codes pertaining to radiationemitting devices;
providing radiation advice and collaborating with other government departments andagencies, industry, and the general public; anddeveloping guidelines for microbiological and chemical contaminants, and radiologicalcharacteristics, in collaboration with the Federal / Provincial / Territorial Committee on
Drinking Water (CDW).

Specifically, Health Canada’s Radiation Protection Bureau has a mandate is to promote andprotect the health of Canadians by assessing and managing the risks posed by radiation exposurein living, working and recreational environments by:

supporting Canada's role in the Comprehensive Nuclear-Test-Ban Treaty by operating theCanadian portion of the International Monitoring System for radionuclides and providing oneof 16 national radionuclide laboratories specified under the Treaty;
conducting assessments under the Canadian Environmental Assessment Act;leading the coordination of federal nuclear emergency preparedness and providing Health
Canada's technical support to the Federal Nuclear Emergency Plan (FNEP);
developing guidance to protect Canadians from the effects of nuclear accidents, radioactivity
in water and food, radon in indoor air, and naturally occurring radioactive materials from
non-nuclear industries;

Page 19 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009







operating the Canadian Radioactivity Monitoring Network and laboratory to provide healthassessments regarding existing levels of radioactivity and effects of nuclear/radiologicalaccidents from a national perspective;
conducting research on the health effects of radionuclides in the environment, especiallysensitive Arctic environments and food chains, and on global air and radionuclide
movements;
providing inter-comparison programs for internal radiation exposure measurements, internal
dosimetry services and research on internal dosimetry and measurements through the
National Calibration Reference Centre for Bioassay and In-Vivo Monitoring;
managing the National Dose Registry, that contains the occupational radiation dose recordsof all monitored radiation workers in Canada. and conducts research on exposure trends andon the health outcomes of occupational exposures;conducting research on exposure trends for radiation workers and on the health outcomes ofoccupational exposures to radiation; andproviding advice to federal departments and agencies, other levels of government, industry,
universities, hospitals, workers and the public on health issues related to radiation exposure.

Provincial Government:
Ministry of the Environment (MOE):
The MOE regulates tritium and other radionuclides in drinking water through the over archinglegislation of the Ontario Safe Drinking Water Act, 2002, and associated regulations, including
Ontario Regulation 169/03 (Drinking Water Quality Standards), Ontario Regulation 248/03(Drinking Water Testing Services), and Ontario Regulation 170/03 (Drinking Water Systems).
There is currently a legally enforceable maximum acceptable concentration (MAC) of 7,000
Bq/L for tritium in drinking water, but monitoring is only mandated through the Certificate ofApproval process, and on a site-specific basis.
Ministry of Labour (MOL):
The MOL’s Radiation Protection Monitoring Service’s (RPMS) main role is to carry out
Ontario’s Nuclear Reactor Surveillance Program, which continuously monitors the environment
for radioactivity around nuclear reactors, in order to assure that public health, safety, andproperty are protected. The RPMS also provides radioactivity measurements of raw and treateddrinking water in support of the MOE’s Drinking Water Surveillance Program (DWSP).
Ministry of Health and Long-Term Care (MOHLTC):
The MOHLTC provides guidance on health issues and coordinates activities between the Chief
Medical Officer of Health and the local Medical Officer of Health (MoH), as appropriate.
Emergency Measures Ontario (EMO):
EMO, a branch of the Ministry of Community Safety and Correctional Services, is responsible
for promoting, developing and maintaining emergency programs throughout the province. In thecase of a nuclear emergency, EMO invokes the Provincial Nuclear Emergency Response Plan, if
appropriate.
Page 20 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Local Government:
Local Medical Officer of Health (MoH):
The local MoH is directly responsible for public health issues, and can order precautionary and /or protective measures, such as Drinking Water Advisories, or recommending the use ofalternate sources of drinking water.
Local Municipalities and Water Treatment Plant Operators:
Local municipalities and water treatment plant operators are required to meet the Ontario
Drinking Water Quality Standards and take corrective action as described in detail in the Safe
Drinking Water Act, 2002, and associated regulations. They are only required to monitor andreport results for tritium if required by their site-specific Certificates of Approval. Drinking
water treatment plant operators currently work with the Ministry of Labour, and the local nuclear
power plants, to collect water samples on a daily basis.
Owners / Operators:
Ontario Power Generation (OPG) and Bruce Power:
OPG and Bruce Power both monitor their discharges as required under their operating licences
regulations as set out by the CNSC. For OPG, a notification limit for tritium is set at 4,000
Bq/L. Exceedance of this limit requires notification to the regulatory agencies and action to
reduce the discharge levels. Bruce Power’s notification limit is 30,000 Bq/L. OPG also collects
water samples taken by local water treatment plant staff and analyzes them for tritium, for both
OPG and Bruce Power facilities.
Atomic Energy of Canada Limited (AECL):AECL is the overseeing body for nuclear facilities, such as Chalk River, and is considered theowner / operator of such. AECL retains ownership of the CANDU technology and licenses its
use to both OPG and Bruce Power, under an agreement.

Page 21 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

3.0

Monitoring and Reporting

The province undertakes an independent monitoring program as part of its surveillance of
nuclear reactors and reports the results annually [MOL, 2008]. Testing is done by the Ministryof Labour laboratory. For tritium, a number of locations are monitored, covering sources ofhuman exposure to tritium such as drinking water, surface water, and well water. Drinking water
samples are generally collected by drinking water treatment plant staff for plants in the vicinityof nuclear power plants and are sent to the Ministry of Labour’s Radiation Protection Laboratory
for analysis. This laboratory is one of only a few that is capable of, and certified for, analysis oftritium at the level of detection that is expected in water. The Ministry of Labour publishes anannual report summarizing all test results for the previous year.
The Ministry of Environment operates the Drinking Water Surveillance Program (DWSP) whichmonitors a wide range of contaminants at many drinking water treatment plants, on an annual
basis, across the province. Tritium is included in DWSP, and the analyses are performed by the
Ministry of Labour laboratory.
It should be noted that there are certain practical limitations to the tests conducted by the
Ministry of Labour, such as equipment limits and the time needed to complete each test. The test
involves allowing the sample of water to remain in a counting chamber for a period of time. The
longer the sample remains in the counting chamber, the more sensitive or lower the detection
limit (i.e. the precision of the test is higher). For practical reasons, a routine tritium test isallowed to remain in the chamber for 100 minutes, which allows the laboratory to handle thecurrent number of samples. With respect to tritium in drinking water, the Minimum Detection
Concentration (MDC) for the Ministry of Labour method is 5 Bq/L [MOL, 2008].
Also, Health Canada’s Radiation Protection Bureau operates the Canadian Radioactivity
Monitoring Network and laboratory to provide health assessments regarding existing levels ofradioactivity and effects of nuclear / radiological accidents from a national perspective.
Nuclear power plants conduct their own drinking water monitoring program in conjunction withlocal municipalities. Samples are taken daily by municipal staff from the water treatment plants
and are combined into a weekly composite sample, which is collected and analysed by Ontario
Power Generation. Their tritium detection level is 4.5 Bq/L (See Appendix 5). Results arereported monthly to the local municipalities and public health offices. Both OPG and Bruce
Power prepare annual reports, in which drinking water results are included with all otherenvironmental testing for a variety of radiological parameters. The results are similar to thosereported by the Ministry of Labour. For detailed results, reference should be made to the various
annual reports issued by the nuclear power facilities [OPG, 2008]; [Bruce Power, 2008a].

Page 22 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
In addition, the nuclear power plants maintain an on-line system for monitoring the tritium levelsin their discharge water or cooling water. In the case of Ontario Power Generation (OPG), themeasurement is taken in the cooling water after mixing and the online monitors have a detection
limit of approximately 3,700 Bq/L (See Appendix 5). The OPG nuclear power plants use a levelof 4,000 Bq/L (See Table 3) [OPG/Bruce Power, 2006] to notify the local Medical Officer of
Health, the Ministry of the Environment, and Emergency Measures Ontario, for coordinatedresponse and corrective actions.
This notification level has not been triggered for a number of years. Flow and dispersion models
are used to predict the concentrations that may occur at the nearest drinking water treatment
plant. For Pickering the models predict that for a discharge of 4,000 Bq/L the level at the Ajax
drinking water plant would be 600 Bq/L and for the Darlington the level at the Bowmanvilledrinking water plant would be 1,100 Bq/L. Bruce Power has as similar system in place, but theirnotification level is 30,000 Bq/L (See Table 5).

Page 23 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

4.0

Health and Risk

This section compares and contrasts the two distinct approaches used for setting standards (theradiological and chemical carcinogen models), outlines some recent and pertinent health studies
and policy directions, and numerically assesses various risk levels.

4.1

Reviews and Reports

As noted in Part I, Section 2.0, in describing the characteristics of tritium, it is the radiologicalactivity of tritium that is of concern rather than any chemical effects or reactions. This is an
important distinction as it has been the basis for two distinct approaches to setting limits: theradiological model and the chemical carcinogen model.
The approach described in the Health Canada document: “Approach to the Derivation of
Drinking Water Guidelines” [Health Canada, 1995b] is similar to that used by most international
regulatory bodies when setting objectives or standards for chemical contaminants in drinking
water. The approach considers differences depending on whether the chemical is a carcinogen ornot. In the case of carcinogenic chemicals, a linear no-threshold approach is generally accepted,
unless details on the mode of action are known or adequate low dose data exist to support a
linear approach with a threshold. Exposure is assumed to be over a life time of 70 years and risk
is related to the incidences of new cancers above the existing background cancer rates.
The radiological paradigm, however, assumes a one-year exposure horizon that will presumably
trigger actions to limit further exposure so that the allowable risk limit is not exceeded, and therisk level is based on cancer deaths (not new incidences of cancer above background).
In setting exposure limits for radiation in general, including tritium, regulators currently consider
all potential exposures to humans from all radionuclide sources. This means that if one source
increases, other sources may have to decrease, so that a total limit is not exceeded. This approachis described in the various references and we will not attempt to repeat it here. The Canadian
Nuclear Safety Commission (CNSC), Canada’s national regulatory body for radiation matters, aswell as other regulatory agencies in other countries take their lead from the International
Commission on Radiological Protection (ICRP). The ICRP sets out a risk framework thatnational organizations may use to establish safety limits and practices for their nuclear industries.
ICRP’s work is based on long-term experience with radiation events and human health effects
research and monitoring, and as such, their initial and primary focus has been on the protectionof workers in the nuclear field [ICRP, 2003].

Page 24 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
There have been several attempts to reconcile the radiological model versus the chemical
carcinogen model to determine if they represent similar levels of protection or precaution, andwhether or not they could be harmonized [Health Canada/AECB/MOEE, 1998]; [HPA, 2007].
These efforts were not entirely successful and it was concluded that it was not fruitful to consider
harmonizing the two approaches in that they provided different, but similar levels of healthprotection.
The divide between the radionuclide and chemical carcinogen paradigms for rule making or risk
assessment was highlighted in the publication entitled: “Risky Business: Claimsmaking in theDevelopment of an Ontario Drinking Water Objective for Tritium” [McMullan, Eyles, 1999].
This publication describes the paradigms and related public policy implications.
There have been several recent assessments or reviews of the health implications of ionizing
radiation, as follows:
A 2004 United Kingdom report by the Committee Examining Radiation Risks of Internal
Emitters raised a number of questions with respect to the ICRP approach and its application bynational regulators [CERRIE, 2004].
The BEIR VII report concluded that, for ionizing radiation, there is a linear-dose response
relationship between exposure to ionizing radiation and the development of radiation induced
cancers in humans, and that there is no safe level for exposure [BEIR, 2006]. The ICRP also
endorses the assumption of this linear-dose response relationship [ICRP, 2007]. It should also be
noted that the “EPA classifies all radionuclides as Group A carcinogens.” [USEPA, 2001a].
A recent United Kingdom report prepared for the Health Protection Agency, by the Advisory
Group on Ionizing Radiation (AGIR), concluded that the ICRP approach was still appropriate butthat for tritium the “Relative Biological Effectiveness” (RBE) should be increased from a factorof 1 to a factor of 2, and consideration be noted for critical groups [AGIR, 2007],
The RBE for a given radionuclide is a measure of its potency for causing biological damage,relative to some standard, usually gamma or X-rays. An RBE of greater than 1 indicates theradionuclide is more potent (i.e. effective) than the reference radiation; conversely, an RBE ofless than 1 indicates that the radionuclide is not as potent as the reference radiation. The RBE isused in dose and risk calculations such as those involved in establishing regulatory standards.
The RBE change for tritium would affect the exposure-cancer relationship and serve to lower thelimit of exposure by 50%.

Page 25 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
As noted in the introduction, the issue of the Ontario Drinking Water Quality Standard fortritium was brought to the attention of the Minister of the Environment by Toronto Public Healthand Greenpeace Canada. Greenpeace commissioned a report by Dr. Ian Fairlie, who is anindependent consultant on radioactivity in the environment, entitled “Tritium Hazard Report:
Pollution and Radiation Risk from Canadian Nuclear Facilities, 2007”. This report documents
the extent of tritium radiation exposure in the environment in Canada and challenges a number of
the assumptions of the ICRP model and the approach used in international jurisdictions, andCanada by the CNSC and the Ontario nuclear industry. It recommends that “safety factors” fortritium be increased by up to a factor of 20 [Greenpeace, 2007].
The Canadian Nuclear Association retained Dr. R. V. Osborne (a biophysicist) to review thereport by Dr. Ian Fairlie. This review contains a comprehensive appraisal of the current
approach taken in Canada and responds to the issues raised by Dr. Fairlie [Osborne, 2007].
In addition to these reports, CNSC held a one day public workshop on the safety issues relating
to tritium. Recognized experts presented papers on various aspects on the issue and participants
had a chance to ask question and debate issues [CNSC, 2008b].
It should also be noted that Recommendation 12 made to federal and state / provincial
governments in the 7th Biennial Report (February, 1994) of the International Joint Commission(IJC) recommended that radionuclides, with a half-life greater than eight weeks (tritium has a
half-life of approximately 12 years) be included in the definition of persistent toxic substances
under the Great Lakes Water Quality Agreement, and that strategies for virtual elimination ofthese pollutants from waste streams be implemented [IJC, 1994].
All of the above noted sources are referenced and are available for more detailed review. This
report does not attempt to describe this information in detail but rather to highlight the
information that the Council members had available and considered throughout this review.

Page 26 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
4.2

Risk Level

Traditionally, the standard setting processes employed by most environmental regulatory bodies
consider 10-6 as the furthest bounds of an acceptable risk level. Acceptable risk levels of 10-6 ormore stringent, are considered to be “de minimis” or trivial [Kelly, 1991]; [Graham, 1993].
Health Canada establishes its Canadian Drinking Water Quality Guidelines for non-thresholdchemical carcinogens at a level which represents an estimated lifetime (70 years) risk of cancer
falling within the range that is considered to be “essentially negligible” or as close to “essentiallynegligible” as reasonably practicable. "Essentially negligible" risk is generally interpreted bymost world-wide regulatory bodies, including Health Canada, as a range of risk of between 10-5
and 10-6.
The ICRP’s “Principle of Optimisation Protection” states that “The likelihood of incurringexposure, the number of people exposed, and the magnitude of their individual doses should all
be kept as low as reasonably achievable, taking into account economic and societal factors.”[ICRP, 2007]. The ICRP notes that “For public exposure in planned situations, the Commission
continues to recommend that the limit should be expressed as an effective dose of 1 mSv in ayear.” [ICRP, 2007]. The ICRP also notes that “The proposed values are implicitly set as afraction of the dose limit” in that the “Dose constraint for public exposure, for prolonged
component from long-lived nuclides” should be “0.1 mSv/year” [ICRP, 2006].
In addition, for carcinogens whose guideline levels have been established at a level above thehealth-based value (due to for example limitations in analytical and treatment technologies),
Health Canada recommends the As Low As Reasonably Achievable (ALARA) principle [Health
Canada, 1995b].
The Ministry of the Environment’s approach to setting health-based Standards for carcinogens indrinking water considers an incremental lifetime risk of 10-6 to be acceptable, and uses this levelas a starting point.
As well, the Ministry of the Environment sets air Standards based on values that protect against
health and environmental effects, as opposed to those that consider technical or economic issues.
For carcinogens, the Standards are set at the 10-6 risk level. An alternative standard process wasdeveloped to establish interim site-specific standards with the goal of continuous improvement
toward achieving the effects-based standard over time [MOE, 2005].
The United States Environmental Protection Agency (USEPA) establishes drinking water
standards for carcinogens as close to zero as possible, considering economic, technical,
treatability and other factors and do not explicitly consider risk. However, the Agency’s
acceptable risk range is from 10-4 to 10-6 [USEPA, 2000].

Page 27 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
The World Health Organization (WHO) establishes drinking water criteria for carcinogens basedon an incremental lifetime risk of 10-5 [WHO, 2004].
An approach to better understand risk is the "Rofecoxib" (Vioxx) Risk Characterization Theatre,
which illustrates and compares the approaches of other agencies and jurisdictions [Strauss,2008].
Risk may also be addressed by applying precautionary measures, such as ALARA (As Low As
Reasonably Achievable), or BATEA (Best Available Technology Economically Achievable).
In the case of Canada’s nuclear industries, exposure and risks are mitigated by applying theconcept of ALARA. For instance, OPG has set an administrative discharge limit of 4,000 Bq/L
for the purpose of reporting to provincial and local authorities and taking corrective action. Thisis measured in the discharge water of the nuclear power plant after mixing with cooling waterand other water discharges. Models are used to predict the expected level of tritium at the closest
water treatment plants. OPG then applies ALARA on a voluntary basis to improve theiroperation and maintenance. By applying ALARA the industry has committed to limiting tritiumin the discharge water such that the level at local drinking water plants will not exceed 100 Bq/L
(See Appendix 4).
For most other industrial discharges in Ontario, the concept of BATEA is applied. However theapplication of BATEA is not voluntary. When Ontario developed discharge limits under the
MISA (Municipal Industrial Strategy for Abatement) program, BATEA was considered before
setting the discharge limits and, as such, the final enforceable discharge limits required theapplication of BATEA. As well, with respect to drinking water, Justice O’Connor did not accept
the concept of voluntary compliance and recommended a stronger and comprehensive regulatory
framework [Walkerton, 2002].
There is general agreement that the incremental lifetime excess cancer risk for a lifetime of
exposure (70 years) to 7,000 Bq/L of tritium in drinking water (approximately equal to 0.1 mSv),
ranges from:

340 in a million [ACES, 1994]; to350 in a million [Appendix 5], which references WHO; to600 in a million [Health Canada, 1995b].

These risk estimates have been used to derive many of the international limits for tritium as
described in Part I, Section 5.0. For Ontario and Canada the limit is 7,610 Bq/L which has beenrounded down to 7,000 Bq/L.

Page 28 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

5.0

Overview of Approaches by Other Jurisdictions

Canada
The approach used to develop Health Canada’s Guideline values for radiological parameters indrinking water are based on using the dose coefficients (DCs) developed by the International
Commission on Radiation Protection (ICRP). The DCs, expressed in sieverts per becquerel, only
provide a quantitative means of expressing radiation dose from the inhalation and ingestion ofradionuclides on the basis of the activity associated with that radionuclide. The DCs are notintended to provide risk estimates for individuals, but rather are a means by which population
effects can be estimated. Moreover, the DCs are not temporally dependent, but are based on
activity of the radiological parameter which has been associated with an adverse effect.
Health Canada, in keeping with the approach used by the World Health Organization (WHO)and other international agencies, has allocated the dose from radionuclides to be in the“essentially negligible” risk range of 10-6 to 10-5, based on an annual exposure. This is a
departure from the approach used for linear no-threshold chemical carcinogens where a life-timeof exposure is generally considered in the setting of a guideline.
The CNSC released a report in 2008 that summarizes the approaches taken by other jurisdictions
in deriving various guidelines and standards for tritium. Reference should be made to this reportfor specific details, but the following table (Table 8) summarizes the findings for a selection ofcountries / jurisdictions. The report also outlines how the limits were derived by eachjurisdiction [CNSC, 2008a].
Table 8: Table of International Limits for Tritium in Drinking Water
Jurisdiction
Health Canada
Ontario
QuébecUnited States EPA
California EPA
European Union
Finland
Switzerland
RussiaAustralia
World Health Organization

Tritium Limit (Bq/L)
7,000
7,000
7,000
740
740; 14.8
100
30,00010,0007,700
76,103
10,000Page 29 of 56

Application
Guideline
Standard
Standard
MCL
MCL / PHG
Screening Value
Standard
Standard
Standard
Guideline
GuidelineReport and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Not all jurisdictions apply their limits in the same fashion. The applications of the limits foundabove in Table 7 are described below:
Guidelines:
The Guidelines for Canadian Drinking Water Quality are established by the Federal-ProvincialTerritorial Committee on Drinking Water (CDW) and are published by Health Canada. However,they are not legally enforceable standards unless promulgated as such by the appropriate
provincial or territorial agency. These guidelines are used by the provinces and territories as abasis for setting maximum permissible levels for microbiological, chemical, and radiologicalparameters.
Standards:
Standards, such as the Ontario Drinking Water Quality Standards, are generally adopted from
Health Canada’s Guidelines for Canadian Drinking Water Quality as legally enforceable
Maximum Acceptable Concentrations (MACs) in Regulation 169/03 (Ontario Drinking Water
Quality Standards) [MOE, 2003], under the Safe Drinking Water Act, 2002 [MOE, 2002].
Maximum Contaminant Levels (MCLs):
Maximum Contaminant Levels, used by the United States Environmental Protection Agency(USEPA), are legally enforceable standards that apply to public water systems. They protect
drinking water quality by limiting the levels of specific contaminants that can adversely affectpublic health and are known or anticipated to occur in water [USEPA, 1996].
Maximum Contaminant Level Goals (MCLGs):
Maximum Contaminant Level Goals, used by the United States Environmental Protection
Agency (USEPA), are set after reviewing health effects studies, at the maximum level of acontaminant in drinking water at which no known or anticipated adverse effect on the health of
persons would occur, and which allows an adequate margin of safety. MCLGs are nonenforceable public health goals. Since MCLGs consider only public health and not the limits ofdetection and treatment technology, sometimes they are set at a level which water systems
cannot meet. When determining an MCLG, the United States EPA considers the risk to sensitive
sub-populations (infants, children, the elderly, and those with compromised immune systems) of
experiencing a variety of adverse health effects.
If there is evidence that a chemical does or may cause cancer, and there is no dose below which
the chemical is considered safe, the MCLG is set at zero. If a chemical is carcinogenic and a safe
dose can be determined, the MCLG is set at a level above zero that is safe [USEPA, 1996].

Page 30 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Public Health Goals (PHGs):
Public Health Goals, used by the California Environmental Protection Agency (CALEPA) for
example, are developed for chemical contaminants, based on the best available toxicological datain the scientific literature, and are set, with an adequate margin of safety, at levels that would
pose no significant health risk to individuals consuming the water on a daily basis over a
lifetime. PHGs are not regulatory and represent only non-mandatory goals. They are, however,used to establish primary drinking water standards (State Maximum Contaminant Levels, orMCLs), which consider economic factors and technical feasibility. Each primary drinking water
standard is set at a level that is as close as feasible to the corresponding PHG, placing emphasison the protection of public health [CALEPA, 2006].
Screening Values:
Screening Values, used by the European Union for example, are used as an indicator of thepresence of other, potentially more harmful radionuclides in drinking water. For instance, if
tritium levels exceed 100 Bq/L, or the Total Indicative Dose (TID) exceeds 0.1 mSv/year, thenfurther investigation is warranted and action may be required, even though these criteria are notconsidered limits.

Page 31 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

6.0

Impacts and Cost implications

An economic study prepared by the Ministry of Environment and Energy (MOEE) in 1994
concluded that there could be significant cost implications to Ontario Hydro if the tritium
drinking water objective were to be made more stringent [MOEE, 1994]. The report noted that if
an annual average was used at levels of 7,000 Bq/L or 100 Bq/L, no additional costs would be
expected, however, if an annual average of 20 Bq/L was considered the costs would be in theorder of $500 million to billions of dollars. If weekly averages were considered, the cost for alevel of 100 Bq/L would be in the order of $650 million to billions of dollars, and for a discretelevel of 20 Bq/L the costs would be in the billions of dollars.
As noted in Part I, Section 1.0, Ontario Hydro, in a letter to the Ministry of the Environment
dated December 9, 1994 agreed that “concentrations of tritium in drinking water will remain lessthan 100 Bq/L on average”. There was no indication that this would require additional costs(Also See Appendix 4).
More recently, as a result of the Council’s public consultation on tritium, the Canadian
Nuclear Association (CNA) wrote to the Council (See Appendix 5) noting that “nuclear power
plants already achieve 20 Bq/L at water supply plants, based on an annual average, but that shortterm control at this level would require the adoption of significant additional technologies withsignificant cost implications”. They also noted that if the tritium standard was revised then “thiswould require lowering all radionuclide limits for drinking water, and it would imply that allemission limits from nuclear power plants, both to air and water should be lowered by a similar
amount…. This would have significant cost implications.” If OPG were required to do daily
analysis this would result in an annualized incremental cost of $1.1 million per year, for analysis
only.
The Medical Officer of Health for the City of Toronto also wrote to the Council on July 28, 2008
(See Appendix 6). He noted that OPG had informed Toronto Public Health that daily analysis
would require substantial increases in both capital and operating costs. It was recognized that thereal issue is chronic (long-term) exposure to tritium and that weekly analysis, as currently
performed, would be appropriate. He recommended immediate notification of drinking waterlevels that exceeded 20 Bq/L, based on analysis of weekly composites, routine monthly reportsof weekly composite results along with a running annual average and immediate notification of
accidental releases of tritium from nuclear facilities.
The Council received no other additional information concerning costs implications of a more
stringent Standard.

Page 32 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

7.0

Stakeholder and Experts Meetings

Over the course of its review, the Council's Tritium Working Group met with knowledgeable
individuals, groups, and stakeholders to inform the whole Council regarding the issues
surrounding an Ontario Drinking Water Quality Standard for tritium. Meetings were held withthe following:













Ontario Power Generation (OPG)
Bruce Power
Canadian Nuclear Safety Commission (CNSC)
Atomic Energy of Canada Limited (AECL)
Radiation Protection Bureau, Health Canada (HC)Former Chair of the Ontario Advisory Committee on Environmental Standards (ACES)
Former Ministry of the Environment (MOE) drinking water experts
Greenpeace Canada
Author of the Greenpeace Canada Report [Greenpeace, 2007]
Toronto Public Health
Toronto Cancer Prevention Coalition, Occupational and Environmental Carcinogens
Working Group
Ministry of Labour (MOL), Radiation Protection Monitoring Service (RPMS)

Documentation provided to the Council as a result of the above meetings has been included inboth the References and Appendices.

8.0

Public Consultation

On March 26 and 27, 2008, the Council held a two-day public consultation meeting on Ontario’s
Drinking Water Quality Standard (ODWQS) for tritium. The purpose of the meeting was toobtain input from a broad spectrum of interested community groups and stakeholders.
Consultation participants were asked for their feedback on the following three questions, as wellas any other feedback they had on the ODWQS for tritium:Is the current Ontario Drinking Water Quality Standard for tritium acceptable?
If not, what is the basis for finding the current Standard unacceptable?
If you propose a different Standard, what is your rationale?

Information on the consultation has been posted on the Council’s website at:
http://www.odwac.gov.on.ca/standards_review/tritium/tritium_consultation.htm

Page 33 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
A total of 65 individuals and organizations participated in the consultation, either by presenting
to the Council, submitting written comments, or both. Participants included:











19 individuals;
11 community-based groups;
8 health organizations (6 health non-governmental organizations and 2 professional
health associations);
6 environmental non-governmental organizations;
5 industry/consulting organizations;
4 municipalities;
3 non-governmental organizations;
2 universities;
1 federal government representative; and1 labour organization.

In addition, the Council received over 500 e-mails and letters from individual members of the
public.
Results from the public consultation have been incorporated along with the input received fromindividuals, and other stakeholders to inform the Council’s advice to the Minister of theEnvironment on the Ontario Drinking Water Quality Standard for tritium. Some of theobservations, concerns, and recommendations are summarized below:
Summary of rationale by those in favour of the current Standard:







Concern for implications on other radionuclide guidelines and standards;
There is no new information that warrants a change to the current Standard;
The methodology for assessing risk and dose for tritium and other radionuclides isinternationally accepted, sufficient and prudent;
The risk of fatal and non-fatal cancers from exposure to radionuclides in drinking water of
0.1 mSv/year is negligible (6 x10-4 over a lifetime);
Making the Standard more stringent would depart from international guidance and advice
from organizations such as the International Commission on Radiation Protection (ICRP) andthe World Health Organization (WHO); andChanging the Standard would create the false impression with the public that there is now ahigher risk from tritium in drinking water.

Page 34 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Summary of rationale by those in favour of a more stringent Standard:



















There is no safe dose of or level to exposure of radiation, and even the smallest doses (e.g.,
background) can cause cancer and other heath effects. Tritium can also promote andaccelerate cancer;
Women are more vulnerable to tritium and are affected differently than men, particularly
with respect to their reproductive systems;
Rapidly growing cells such as fetal tissue and young girls’ developing breasts, genetic
materials and blood forming organs are especially sensitive to tritium;
Tritium can damage DNA, causing a mutagenic effect resulting in cancers, miscarriages,
birth defects, sterility, and hypothyroidism, among others. The effects from exposure totritium can harm offspring and last for generations;Female human infants are at risk from elevated tritium levels due to genetic damage to ova
exposed to tritiated hydrogen;
Certain groups are especially vulnerable to environmental carcinogens, such as women(especially when pregnant), the unborn, and the elderly, those with compromised immune
systems, children, teenagers and Aboriginal people;
How risk and dose measurements are calculated, particularly in that the current models use
the “standard man”, which may not reflect dosages experienced by women and children;
Exposure studies based on animal testing are not accurate because of the lower body fat
levels found in animals;
Many of the non-lethal cancer effects of tritium are not currently considered in the model
upon which the current Standard is based on. These effects include non-fatal cancers,
miscarriages, still births, birth defects, sterility, hypothyroidism, genetic mutation, respiratory
failure, kidney failure, nervous system disorders, cardiovascular disease, among others;
The current Standard does not consider organically-bound tritium, thus under-estimating thetrue dose;
Cumulative exposure and combined effects are not being considered;
The current Standard considers 340 excess fatal cancers per million as an “acceptable risk”,
which is equivalent to 1 in 3,000;
Anthropogenic emissions of tritium directly impact the drinking water supplies ofapproximately one-quarter of the Canadian population, thereby resulting in a large population
being exposed involuntarily;
Levels of tritium are 2 to 5 times higher in Lake Ontario than in other water bodies in the
Great Lakes and across Canada, and Lake Ontario is a major source of drinking water for
Ontarians;
Between 1979 and 1997, there were 11 known leaks of tritium from Canadian nuclear
reactors;
Elevated concentrations of tritium are also reported to have been found in food and well
water samples in the proximity of nuclear reactors in Southern Ontario;
The risk of exposure to tritium is higher due to the facilities proximity and their use of
deuterium;

Page 35 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009Concern that Canada’s current Guideline for tritium in drinking water (which is the same as
Ontario’s Standard) is unacceptable because it is high compared to other jurisdictions; andIt was felt that the precautionary approach was not being applied with respect to tritium indrinking water and that because there is still uncertainty over the impacts of tritium (such assynergistic effects with other substances), then the precautionary principle should be applied
and the Standard should be lowered.

For more details, reference should be made to the report: “Ontario Drinking Water Advisory
Council: Public Consultation on the Ontario Drinking Water Quality Standard for Tritium” (SeeAppendix 7).

Page 36 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009Part II
1.0

Conclusions

Part I of this report summarizes the work the Council undertook to become informed on mattersrelated to tritium in drinking water. Throughout the process of collecting information andresearching and receiving information and advice from experts, stakeholders and the concerned
public, Council members met regularly to critically discuss and assess the information.
Through this review process, the Council arrived at a series of specific inferences which
contributed to and assisted in reaching consensus on conclusions about the nature of tritium, andits regulation in drinking water. These key conclusions are as follows:

1.1

Background and Sources

There is a natural background level of tritium in water in Ontario, which is generally less than 2
Bq/L. Tritium is naturally formed in the upper atmosphere by cosmic rays, and enters surface
water and groundwater via rainfall. Tritium was also produced during above-ground nuclear
weapons explosions, and is currently produced as a by-product of nuclear reactors which use
deuterium or “heavy water”.
The primary man-made source of tritium and subsequently tritium in drinking water isdischarges from nuclear facilities. The nuclear industry has a well established program to
manage, control and limit tritium discharges under the regulation of the CNSC.
Over the last decade monitoring data from drinking water plants indicate that annual averagetritium levels are well below 100 Bq/L, and in fact, in most cases, below 20 Bq/L.
There is no treatment technology available to remove tritium at drinking water treatment plants.
The only approach to lower tritium levels in drinking water is to avoid contamination of thesource water.
The Council noted that Ontario’s nuclear power plants apply the concept of As Low As
Reasonably Achievable (ALARA) to reduce tritium discharges to levels below their regulated
discharge limits and, as a result, they can achieve their commitment to keep tritium levels below
100 Bq/L at local drinking water treatment plants.

Page 37 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Ontario’s approach to industrial discharges to water under the Municipal-Industrial Strategy for
Abatement (MISA) program is to apply Best Available Technology Economically Achievable(BATEA) before assigning a discharge limit. Both these approaches reflect the Precautionary
Principle; however ALARA leaves the discretion with the industry. The Council prefers theprovince’s BATEA approach for regulating discharges to the environment and subsequently tosources of drinking water, due to its application prior to setting discharge limits.

1.2

Health Risks

The Council agrees with the conclusions of the BEIR VII report that there is linear dose-response
relationship and no threshold for the induction of cancers by radionuclides [BEIR, 2006].
However, it is also acknowledged that at levels below the range where there are measured data,
there is a high degree of uncertainty as to the shape of the dose-response curve.
The measures for risk should be based on cancer incidences above background (occurrences)rather than mortality (deaths).
The Council concludes that the target derived risk level should be 1 in a million or 10-6 (meaning
1 new excess cancer occurrence over existing background cancer rates in 1,000,000 people).
The Council also concludes that the target derived risk level should be based on a lifetime of
exposure of 70 years, since this incremental risk better reflects the realities of chronic or longterm exposure to tritium in drinking water than does an annual exposure.
The target derived risk level of 1 new excess cancer occurrence over existing background cancer
rates in 1,000,000 people, based on a lifetime of exposure of 70 years, is consistent with theapproach used for non-threshold chemical carcinogens, but there may be practical reasons for
accepting or adopting a different level of risk, such as technology, economic, and time issues.
The Council agrees that a Relative Biological Effectiveness (RBE) factor of at least 2 should be
used, where appropriate, in deriving exposure limits for tritium.
The research literature and specialists in the field have made extensive references to the time
tritium remains in the human body, once exposed to tritium in drinking water (referred to as the
biological half-life). The Council concludes that when intake is constant, as is the case indrinking water, tritium levels in the human body will reach an equilibrium value related to thetritium level in the drinking water. This important distinction is in contrast to occupational
exposures, which may vary or may exceed annual limits in shorter periods of time, thus
accounting for the need to amortize the doses (exposures) on a yearly basis.

Page 38 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
1.3

Monitoring and Reporting

From the perspective of monitoring and reporting, sampling should only be required at drinking
water treatment plants that are in the vicinity of or under the influence of known or suspectedsources of tritium. A province-wide sampling program by municipal water authorities is not
required nor warranted.
The Ministry of Labour (MOL) should continue to conduct the water sample testing under their
Nuclear Reactor Surveillance Program, and water treatment plant operators should continue tocollect the samples for analysis. Sampling and reporting should be done per the current MOL
practices, as these methods and procedures remain appropriate.
The Ministry of the Environment’s Drinking Water Surveillance Program (DWSP) is an
excellent approach for broader province-wide monitoring, aimed at assessing levels and trends,
including radiological characteristics, and should continue.
The nuclear power industry should also continue with their current monitoring program in
conjunction with local municipalities and drinking water authorities.
It is recognized that there are sources of tritium other than from nuclear power plants. Highlevels of tritium were recently found in private wells in the vicinity of an industrial operation
which used tritium. Monitoring requirements should apply to water treatment plants near theseother sources and regulations should be flexible enough to permit the inclusion of other locations
if new sources are identified.
It was also noted that samples can be taken at any convenient location in the drinking water
treatment plant, since the concentration of tritium in the water will not be changed by any of theplant’s treatment processes.
All tritium data and information should be made available by the nuclear power industry and theMinistry of Labour, to the public, the Ministry of the Environment, and local public healthoffices, as soon as practicably possible.

1.4

Cost Issues

The nuclear power industry and its association, the CNA, have expressed a concern that if theOntario Drinking Water Quality Standard for tritium is derived by applying a different paradigm
or approach than which is currently used by the radiological sector, then a revision to theirapproach for the application of other regulatory requirements for other radionuclides would also
be required, resulting in “significant cost implications” (See Appendix 5). The Council disagrees
that the principles used in the development of an Ontario Drinking Water Quality Standard fortritium should guide occupational or other standards.

Page 39 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Tritium is the main radionuclide found in drinking water in Ontario and represents an on-going,
active source of radioactivity above background levels, resulting in lifetime exposure to large
populations. There is also the potential for large populations to be exposed to acute levels.
Thus, the approach taken for regulating tritium in drinking water should not imply that it isappropriate for other radiologically-regulated activities or radionuclides.

1.5

Corrective Actions

It should be stressed that the proposed Standard for tritium in drinking water is based on longterm exposure and potential health implications. As such, short-term exposure to drinking waterthat moderately exceeds the Standard should not trigger inappropriate responses by government
agencies or the public. Such exceedances should be used to set in motion a series of corrective
actions to be taken by the discharger of the tritium to the environment. Water utilities andprovincial agencies should be monitoring the trends of reported test results and should seekcorrective actions if the trends indicate that levels are increasing and that the Standard may be
exceeded if action is not taken.
Urgent actions to protect the public from more immediate exposure to tritium should be based onmonitoring sources of tritium at the point of discharge. Water treatment plants cannot remove or
treat for tritium in the source water, so the only response may be to shut down the water intake
and rely on storage or use alternate sources of drinking water, during emergency situations. Thiscan only be done in an effective manner if information on source discharges and models thatpredict the potential for that discharge, and expected tritium levels at water treatment plants, arein place. Short-term or urgent actions to protect neighbouring communities should be based on
on-going monitoring and reporting from the sources of tritium and not based on sampling andreporting by drinking water treatment plants.

2.0

Developing the Standard

In Ontario, a drinking water Standard must be acceptable or “safe” to allow that water to be
consumed each day over a lifetime of 70 years at the Standard. Recommendation 18 of the Part
Two Report of the Walkerton Inquiry states that “In setting drinking water quality standards, theobjective should be such that, if the standards are met, a reasonable and informed person would
feel safe drinking the water” [Walkerton, 2002].
The technical challenge is how to best utilize the available radiological research and information
to arrive at a risk as close to 1 in a million (10-6) as possible, while maintaining practicability andachievability.

Page 40 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
In an effort to arrive at a proposed Standard, the Council evaluated several numerical variations
that use the models of other jurisdictions and authorities and revised them to reflect the earlier
conclusions. These variations are not independent, as they are derived using initial criteria usedby Health Canada and other jurisdictions, and the ICRP. The purpose of examining thesevariations (found below in Section 2.1) is to test how the Council’s earlier stated conclusions
would result in differing outcomes.

2.1

Numerical Variations

Lifetime Risk from a Lifetime of Exposure Variation
 Start with unrounded Ontario Drinking Water Quality Standard for tritium of 7,610 Bq/L
 Divide by 70 years to represent a lifetime of exposure ≈ 109 Bq/L
Lifetime Risk from a Lifetime of Exposure + RBE Variation
 Start with unrounded Ontario Drinking Water Quality Standard for tritium of 7,610 Bq/L
 Divide by 70 years exposure to represent a lifetime of exposure Apply a Relative Biological Effectiveness for tritium of 2
 ≈ 54 Bq/L
Risk of 10-6 Variation 1
 Start with 0.1 mSv/year which is approximately equal to 7,000 Bq/L Apply Nominal Probability Coefficient for fatal cancer induction of 5.0 x 10-2 Sv-1 [ICRP,
1991]
 Multiply by 70 years to represent a lifetime
 5.0 x 10-2 Sv-1 x 0.1 mSv/year x 70 years = approximately 3.4 x10-4 incremental lifetime riskover a lifetime of exposure Convert to a risk of 10-6 (7,000 Bq/L x 10-6)/3.4 x10-4
 ≈ 20 Bq/L
Risk of 10-6 Variation 2
 Start with the risk of fatal and weighted non-fatal conditions at a lifetime exposure of 0.1
mSv/year of between 10-5 and 10-6, which is approximately equal to 6 x 10-4 over a lifetime[Health Canada, 1995b]
 Multiply by 70 years to represent a lifetime
 Convert to a risk of 10-6 (7,000 Bq/L x 10-6)/6 x10-4
 ≈ 12 Bq/L

Page 41 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Risk of 10-6 Variation 3
 Start with the Nominal Probability Coefficient for fatal cancer induction of 5.0 x 10-2 Sv-1
[ICRP, 1991]
 The amount of Sv to result in a risk of 10-6 is 10-6/5×10-2 = 2×10-5Sv
 The number of Bq that will result in a dose of 2×10-5Sv is 2×10-5Sv/ 1.8×10-11 Sv/Bq [WHO,2004] which is = 1.1×106 Bq
 Multiply 730 L per year by 70 to arrive total lifetime water consumption = 51,100 L
 Calculate amount of tritium that could be present in drinking water: 1.1×106 Bq / 51,100 L ≈ 22 Bq/L
Chemical Carcinogen Variation
 Start with a chemical carcinogen model, using the Nominal Probability Coefficient for fatal
cancer, non-fatal cancer, and severe hereditary effects induction of 7.3 x 10-2 Sv-1 [ICRP,
1991]
 0.1 mSv/year = a risk of approximately 7.3 x 10-6/year 0.0137 mSv/year = a risk of approximately 1 x 10-6/year 0.0137 mSv/70 years = a risk of approximately 1.96 x 10-4 mSv/year Use 1.96 x 10-4 mSv/year as numerator in MAC Calculation (instead of 0.1 mSv/year) ≈ 15 Bq/L ≈ 7.5 Bq/L (if Relative Biological Effectiveness for tritium of 2 applied)
Risk Assessment Information System Variation
 Start with the Risk Assessment Information System Cancer Risk Value (Potency) for tritiumof 5.07 x 10-14/pCi [USEPA, 2001b] (5.07 x 10-14/pCi) x (pCi/0.037 Bq) (1 pCi = 0.037 Bq)
 (1.37 x 10-12/Bq) x (3.58 x 108 Bq over 70 years)
 4.9 x 104 risk at 7,000 Bq/L
 Convert to 1 x 10-6 risk ≈ 14 Bq/L
 ≈7 Bq/L (if Relative Biological Effectiveness for tritium of 2 applied)
These variations result in a range for a possible Standard of approximately 7 Bq/L to 109 Bq/L.
The Council, therefore, concludes that the appropriate proposed Standard is within the range ofthe variations, since the range fell within a circa 10-6 risk.
The Council also concludes that these variations, based on current science and risk assessment
practices, will not lead to consensus on a single number.

Page 42 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
2.2

Reaching Consensus on a Numerical Standard

Since the Council could not unequivocally select one variation over another, given that theuncertainties in the scientific methods do not confirm any one particular value over another fromwithin the range, the following question was considered:Taking into account all the research and documentation, meeting with experts,
stakeholders, and the general public, and Council deliberations, is there a tritiumStandard (value or level) that a reasonable and informed person would feel safe
drinking the water every day over a lifetime of 70 years at or below that
Standard?
To answer this question, the Council went back to address some of the basic principles or criteria
used by Health Canada for setting Canadian Drinking Water Quality Guidelines for nonthreshold chemical carcinogens. This would mean that the maximum acceptable concentration
should be established at a level which represents an estimated lifetime (70 years) risk of cancer
falling within the range that is considered to be “essentially negligible” or as close to “essentiallynegligible” as reasonably practicable. "Essentially negligible" risk is generally interpreted bymost world-wide regulatory bodies, including Health Canada, as a range of risk of between 10-5
and 10-6.
However, the Council concluded that the target derived risk level for tritium in drinking water in
Ontario should be 1 in a million or 10-6.
In addition, for carcinogens whose guideline levels have been established at a level above thehealth-based value (due to for example limitations in analytical and treatment technologies),
Health Canada recommends the As Low As Reasonably Achievable (ALARA) principle [Health
Canada, 1995b].
Using the variations outlined above in Section 2.1, the Council demonstrated that theconcentration of tritium for a risk of 10-6 is somewhere between 7 Bq/L and 109 Bq/L. The next
step is to determine what limit would be “reasonably practicable”. To address this, we turned totwo documents received by the Council as part of consultation process:

The Canadian Nuclear Association noted in a letter to the Council that 20 Bq/L on an annual
average basis is achievable in drinking water, without significant cost to the industry (SeeAppendix 5).

The Toronto Medical Officer of Health noted in a letter to the Council that the concern withtritium is chronic exposure, and that an annual average of 20 Bq/L would not be exceeded if
Ontario Power Generation did not exceed its current discharge limit of 4,000 Bq/L (at either
Pickering or Darlington Nuclear Power Generating Stations) (See Appendix 6).

Page 43 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Based on these two documents, the Council concluded that an Ontario Drinking Water Quality
Standard for tritium of 20 Bq/L, applied as a running annual average, would meet therequirements for an appropriate level of risk and public safety, while remaining practicable andachievable by the nuclear power industry.
The current data support this conclusion, in that all of Ontario’s nuclear power generators are
currently capable of controlling their liquid tritium discharges, to the extent that local water
treatment plants should be able to meet the new Standard. The Council expects that this highlevel of industry performance will continue and improve.
The Council further noted that, in applying a test of practicability to this proposed Ontario
Drinking Water Quality Standard for tritium, it should not be necessary for the nuclear powerindustry to alter any of the applicable regulations for occupational or other radiological criteria.
The Council's approach is unique to the lifetime commitment of exposure to tritium fromdrinking water in Ontario, in that there are multiple, on-going sources capable of exposing large
populations of people in some communities, to levels above background.
It should be noted, however, that the current level of risk for exposure to tritium in drinking
water and potential health implications will not change with a more stringent Standard. That is
to say, there would be no elevated risk to exposed populations as a result of a more stringent
Standard. A more stringent Standard, however, will help to predict future risk by finding
problems more quickly through surveillance and increased frequency of sample result reporting.

Page 44 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

3.0

Recommendations

1. The Ontario Drinking Water Quality Standard for tritium should be revised to 20 Bq/L,
recognizing that:

20 Bq/L relates to heath effects from long-term, chronic exposure from drinking waterover a life time of exposure of 70 years;



20 Bq/L is within the range of the variations considered by the Council (7 Bq/L to 109
Bq/L), for a 10-6 risk level; and

20 Bq/L, based on an annual average, is achievable in drinking water, without significant
cost to the nuclear power industry, according to the Canadian Nuclear Association.

2. The Standard of 20 Bq/L should be applied as the running average of the preceding 52
weekly composite samples. This running annual average is consistent with the current
weekly sampling and reporting programs, and should also be used to generate monthly
averages and identify trends.
3. The current sampling and monitoring programs, as conducted by the Ministry of Labour andthe industry, are appropriate, and should continue. Sampling and reporting should only berequired for those drinking water treatment plants that are in proximity of or under the
influence of sources of tritium. As well, the Ministry of the Environment should continue tomonitor tritium at drinking water systems as part of the Drinking Water Surveillance
Program (DWSP).
4. Monthly reports of weekly test results and running annual averages should be sent toregulatory bodies, local municipalities and health units, local public interest groups, andshould also be made available to the general public.
5. It is equally important to monitor trends in the monthly data and if there is an indication ofincreases (even if they are below the Standard), the province should require the discharger totake appropriate corrective actions, in collaboration with other appropriate authorities.
6. Monitoring and reporting at the point of discharge should be the focus for emergency
response in that monitoring at drinking water treatment plants is not an appropriate approach
for alerting authorities and the public of significant and / or elevated discharges of tritium.
The current program should be enhanced to require the dischargers to report monthly toregulatory authorities and other public bodies on the levels of tritium discharges andimmediately in each case where discharges exceed designated notification level(s).

Page 45 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Acronyms
ACES
AECL
AECB
AGIR
ALARA
BATEA
BEIR
Bq
Bq/L
CALEPACANDU
CDWQG
CERRIE
CNA
CNSC
DC
DNA
DRL
DWSP
EMO
HC
HT
HTO
ICRP
IJC
L
MAC
MBq
MCL
MCLG
MDC
MOE
MOEE
MoH
MOHLTC
MOL
MISA
mSv
NAS
NRC
ODWAC

Advisory Committee on Environmental Standards
Atomic Energy of Canada Limited
Atomic Energy Control Board
Advisory Group on Ionising Radiation
as low as reasonable achievable
best available technology economically achievable
Biological Effects of Ionizing Radiationbecquerelbecquerel per litre
California Environmental Protection Agency
Canadian Deuterium Uranium class of fission reactor
Canadian Drinking Water Quality Guideline
Committee Examining Radiation Risks of Internal Emitters
Canadian Nuclear Association
Canadian Nuclear Safety Commission
dose coefficient
deoxyribonucleic acidderived release limit
Drinking Water Surveillance Network
Emergency Measures Ontario
Health Canada
tritium gas
tritiated waterInternational Commission on Radiological Protection
International Joint Commission
litre
maximum acceptable concentration
megabecquerel
maximum contaminant level
maximum contaminant level goal
minimum detectable concentration
Ministry of the Environment
Ministry of Environment and Energy
Medical Officer of Health
Ministry of Health and Long-Term Care
Ministry of Labour
Municipal Industrial Strategy for Abatement
millisievert
National Academy of Sciences
National Research Council
Ontario Drinking Water Advisory Council
Page 46 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
ODWO
ODWQS
OBT
OPG
PHG
RBE
RPMS
TBq
TID
USEPA
WHO

Ontario Drinking Water Objective
Ontario Drinking Water Quality Standard
organically bound tritium
Ontario Power Generation
public health goal
relative biological effectiveness
Radiation Protection Monitoring Service
terabecquerel
total indicative dose
United States Environmental Protection Agency
World Health Organization

Page 47 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

References
ACES, 1994. Ontario Advisory Committee on Environmental Standards. A Standard for
Tritium: A recommendation to the Minister of the Environment and Energy. Report 94-01.
Ontario, Canada.
http://www.odwac.gov.on.ca/standards_review/tritium/1994_ACES_Report_Tritium.pdf
AECL, 2007. Atomic Energy of Canada Limited. Annual Performance Report. AECL Annual
Environmental Performance Report for 2006. CW-509241-REPT-003 Revision 0. December,2007. Mississauga, Ontario.
http://www.aecl.ca/Assets/Publications/Reports/CW-509241-REPT-003.pdf
AGIR, 2007. Advisory Group on Ionising Radiation. Review of Risks from Tritium. Report ofthe independent Advisory Group on Ionising Radiation (RCE-4), on behalf of the HealthProtection Agency. United Kingdom.
http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1197382220012?p=1199451989432
BEIR, 2006. Advisory Committee on the Biological Effects of Ionizing Radiation. Health
Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII – Phase 2. Board on
Radiation Effects Research, Division of Earth and Life Studies, National Research Council of the
National Academies, The National Academies Press, Washington, D.C.
http://www.nap.edu/catalog.php?record_id=11340
Bruce Power, 1996. Notification/Action Protocols for Abnormal Releases at BNPD. B-CORR00548-0002. March 4, 1996.
http://www.odwac.gov.on.ca/standards_review/tritium/BNPD_Tritium_Release_Protocol_1996.
pdf
Bruce Power, 2008a. Annual Summary & Assessment of Environmental Radiological Data for2007. B-REP-03419-00008 R000. April 23, 2008. Ontario, Canada.
http://www.brucepower.com/uc/GetDocument.aspx?docid=2608
Bruce Power, 2008b. Bruce Power’s Derived Release Limits and Environmental Action Levels.
http://www.odwac.gov.on.ca/standards_review/tritium/Bruce_B_DRL.pdf
CALEPA, 2006. California Environmental Protection Agency. Public Health Goals for
Chemicals in Drinking Water: Tritium.
http://oehha.ca.gov/water/phg/pdf/PHGtritium030306.pdf

Page 48 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
CERRIE, 2004. Report of the Committee Examining Radiation Risks of Internal Emitters.
October 2004. London, England.
http://www.cerrie.org/pdfs/cerrie_report_e-book.pdf
CNSC, 2008a. Canadian Nuclear Safety Commission. Standards and Guidelines for Tritium in
Drinking Water. INFO-0766. January, 2008. Ottawa, Canada.
http://www.nuclearsafety.gc.ca/eng/readingroom/healthstudies/tritium/
CNSC, 2008b. Canadian Nuclear Safety Commission. Draft Tritium Workshop Report.
January, 2008. Ottawa, Canada.
http://www.nuclearsafety.gc.ca/eng/getinvolved/sessionworkshop/past/workshop_20080118/Wk
shop_2008018_summary.cfm
Fairlie, 2007. Dr. Ian Fairlie. RBE and WR values of Auger emitters and low-range beta
emitters with particular reference to tritium. Ian Fairlie. Journal of Radiological Protection 27(2007) 157-168.
http://www.iop.org/EJ/article/0952-4746/27/2/003/jrp7_2_003.pdf
Fairlie, 2008. Dr. Ian Fairlie. Radiation Risks of Tritium: Additional Note for ODWAC.
January 31, 2008. London, England.
http://www.odwac.gov.on.ca/standards_review/tritium/Tritium_Radiation_Risks_Additional_No
te_for_ODWAC_Fairlie.pdf
Graham, 1993. John D. Graham. The Legacy of one in a million. Harvard Center for Risk
Analysis. Risk in Perspective. March 1993. Volume 1, Number 1.
http://www.hcra.harvard.edu/rip/rip_Mar_1993.pdf
Greenpeace, 2007. Greenpeace Canada. Tritium Hazards Report: Pollution and Radiation Risks
from Canadian Nuclear Facilities. June, 2007. Authored by Dr. Ian Fairlie. London, England.
http://www.greenpeace.org/raw/content/canada/en/documents-and-links/publications/tritiumhazard-report-pollu.pdf
Health Canada, 1994. Human Health Risk Assessment for Priority Substances (approach used
under the Canadian Environmental Protection Act). 1994. ISBN 0-662-22126-5. Ottawa,
Canada.
http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/approach/index-eng.php
Health Canada, 1995a. Radiological characteristics. February, 1995. Edited April, 1995.
Health Canada, Ottawa, Canada.
http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/radiological_characteristics/index-eng.php
Health Canada, 1995b. Part I. Approach to the Derivation of Drinking Water Guidelines.
February, 1995. Health Canada, Ottawa, Canada.
www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/part_i-partie_i/index-eng.php
Page 49 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Health Canada/AECB/MOEE, 1998. Health Canada, Atomic Energy Control Board, andOntario Ministry of Environment and Energy Joint Working Group. Assessment andManagement of Cancer Risks from Radiological and Chemical Hazards. Ontario, Canada.
http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/98ehd-dhm216/index-eng.php
Health Canada, 2006. Radiological characteristics of Drinking Water. July, 2006. Documentfor Public Comment. Health Canada, Ottawa, Canada.
http://www.odwac.gov.on.ca/standards_review/tritium/2006_HC_Radiologicals_Public_Comment_Document.pdf
Health Canada, 2008. Guidelines for Canadian Drinking Water Quality Summary Table. May,
2008. Health Canada. Ottawa, Canada.
http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/sum_guide-res_recom/index-eng.php
HPA, 2007. Health Protection Agency. Comparison of Processes and Procedures for Deriving
Exposure Criteria for the Protection of Human Health: Chemicals, Ionising Radiation and Nonionising Radiation (RCE-3). J R Cooper, R Fielder, R Jefferson, J R Meara, K R Smith and J W
Stather. July, 2007. United Kingdom.
http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1200055665320?p=1199451989432
ICRP, 1991. International Commission on Radiological Protection. 1990 Recommendations of
the International Commission on Radiological Protection. Annals of the ICRP, 21(1.3). Oxford,
Pergamon Press (Publication 60).
http://www.elsevier.com/wps/find/bookdescription.cws_home/29083/description#description
ICRP, 2003. International Commission on Radiological Protection. International Commission
on Radiological Protection: History, Policies, Procedures. Bo Lindell, H John Dunster, and Jack
Valentin. 2003. Stockholm, Sweden.
http://www.icrp.org/prod03.asp
ICRP, 2006. International Commission on Radiological Protection. ICRP Supporting Guidance
5. Analysis of the Criteria Used by the International Commission on Radiological Protection tojustify the Setting of Numerical Protection Level Values. Annals of the ICRP, Vol. 36 No. 4.
Published by Elsevier.
http://www.elsevier.com/wps/find/bookdescription.cws_home/711542/description#description
ICRP, 2007. International Commission on Radiological Protection. ICRP Publication 103:
Recommendations of the International Commission on Radiological Protection. Annals of the
ICRP, Volume 37, Nos. 2-4, 2007. Published by Elsevier.
http://www.elsevier.com/wps/find/bookdescription.cws_home/713998/description#description

Page 50 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
IJC, 1994. International Joint Commission. Seventh Biennial Report Under the Great Lakes
Water Quality Agreement of 1978.
http://www.ijc.org/php/publications/html/7bre.html
JRP, 2008. Journal of Radiological Protection. Internal dosimetry and tritium – the ICRP
position. Roger Cox et al 2008. J. Radiol. Prot. 28 131-135. doi: 10.1088/09524746/28/2/E02J.
http://www.iop.org/EJ/abstract/0952-4746/28/2/E02
Kelly, 1991. Kathryn Kelly. The Myth of 10-6 as a Definition of Acceptable Risk. Kathryn
Kelly, Delta Toxicology, Inc.
http://www.heartland.org/custom/semod_policybot/pdf/17603.pdf
Little/Lambert, 2007. M. P. Little and B. E. Lambert. Systematic review of experimental
studies on the relative biological effectiveness of tritium. M. P. Little and B. E. Lambert,
Radiation Environmental Biophysics (2007) 47:71-93
http://www.springerlink.com/content/262x706282774807/fulltext.pdf
McMullan, Eyles, 1999. Risky Business: An Analysis of Claimsmaking in the Development ofan Ontario Drinking Water Objective for Tritium. Published by the University of California
Press for the Society for the Study of Social Problems, Vol. 46, No. 2 (May, 1999) pages 294311, Colin McMullin, John Eyles.
http://www.jstor.org/stable/3097257
MOE, 2002. Ontario Ministry of the Environment. Safe Drinking Water Act, 2002.
http://www.e-laws.gov.on.ca/html/statutes/english/elaws_statutes_02s32_e.htm
MOE, 2003. Ontario Ministry of the Environment. Ontario Regulation 169/03. Ontario
Drinking Water Quality Standards. (As amended to O. Reg. 327/08).
http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_030169_e.htm
MOE, 2005. Ministry of the Environment. Guideline for the Implementation of Air Standards in
Ontario. July, 2005. PIBS # 5166e.
http://www.ene.gov.on.ca/envision/gp//5166e.pdf
MOEE, 1993. Ontario Ministry of Environment and Energy. Rationale Document for theDevelopment of an Interim Ontario Drinking Water Objective for Tritium. November, 1993.
Standards Development Branch.
http://www.odwac.gov.on.ca/standards_review/tritium/1993_MOEE_Rationale_Doc_Tritium.pdfPage 51 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
MOEE, 1994. Ontario Ministry of Environment and Energy. Economic Consequences of an
ODWO for Tritium. Economic Services Branch. December, 1994. Ontario, Canada.
http://www.odwac.gov.on.ca/standards_review/tritium/1994_Economic_Consequences_of_an_O
DWO_for_Tritium.pdf
MOL, 2008. Ontario Ministry of Labour. Radiation Protection Monitoring Service. Nuclear
Reactor Surveillance Program 2007 Report to the Radiation Monitoring Working Group.
October 31, 2008. Ontario, Canada.
http://www.odwac.gov.on.ca/standards_review/tritium/MOL_RPS_Annual_Report_2007.pdf
OPG, 2007. Ontario Power Generation. Attachment to email of August 10, 2007, I. Benovich
to S. Barrett, “Types and Levels of ‘Spills’ ”
http://www.odwac.gov.on.ca/standards_review/tritium/OPG_Types_and_Levels_of_Spills.pdf
OPG, 2008. Ontario Power Generation. 2007 Results of Radiological Environmental
Monitoring Programs. N-REP-03481-10006-R000. April 23, 2008. Ontario, Canada.
http://www.ontariopowergeneration.com/pdf/Nuclear%20Reports%20and%20Publications/2007%20Radiological%20Environmental%20Monitoring%20Program%20(REMP)%20Report.pdf
OPG/Bruce Power, 2006. Ontario Power Generation / Bruce Power. Coordination of the
Response to a Liquid Emission at OPG and Bruce Power.
http://www.odwac.gov.on.ca/standards_review/tritium/OPG_BRUCE_Liquid_Emission_Respon
se_Procedure.pdf
Osborne, 2002a. R. V. Osborne, 2002. Tritium in the Canadian Environment: Levels and
Health Effects. RSP-0153-1. Prepared for the Canadian Nuclear Association. March 22, 2002.
Ranasara Consultants Inc., Deep River, Ontario.
http://www.odwac.gov.on.ca/standards_review/tritium/Osborne_CNSC-RSP-0153-1.pdf
Osborne, 2002b. R. V. Osborne, 2002. Tritium in the Canadian Environment: Questions andAnswers. RSP-0153-2. Prepared for the Canadian Nuclear Association. June 26, 2002.
Ranasara Consultants Inc., Deep River, Ontario.
http://www.odwac.gov.on.ca/standards_review/tritium/Osborne_CNSC-RSP-0153-2.pdf
Osborne, 2007. R. V. Osborne, 2007. Review of the Greenpeace report: “Tritium Hazard
Report: Pollution and Radiation Risk from Canadian Nuclear Facilities” I. Fairlie, 2007 June.
Prepared for the Canadian Nuclear Association. August 13, 2007. Ranasara Consultants Inc.,
Deep River, Ontario.
http://www.cna.ca/english/pdf/Studies/ReviewofGreenpeacereport_Final.pdf#search="Osborne"
SRB, 2009. SRB Technologies (Canada) Inc. 2008 Annual Compliance Report. March 31,
2009. Pembroke, Ontario.
http://www.betalight.com/pip/compliance-2008.pdf

Page 52 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009
Strauss, 2008. Stephen Strauss. Picture this: a new way of seeing risk. Salon: Canadian
Medical Association Journal. May 20, 2008; 178 (11).
http://www.cmaj.ca/cgi/reprint/178/11/1512
UNSCEAR, 2000a. United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and Effects of Ionizing Radiation. Volume I: Sources. UNSCEAR 2000 Report to theGeneral Assembly, with Scientific Annexes (New York: United Nations).
http://www.unscear.org/unscear/en/publications/2000_1.html
UNSCEAR, 2000b. United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and Effects of Ionizing Radiation. Volume II: Effects. UNSCEAR 2000 Report to theGeneral Assembly, with Scientific Annexes (New York: United Nations).
http://www.unscear.org/unscear/en/publications/2000_2.html
UNSCEAR, 2001. United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and Effects of Ionizing Radiation. Hereditary Effects of Radiation. UNSCEAR 2001
Report to the General Assembly, with Scientific Annex (New York: United Nations).
http://www.unscear.org/unscear/en/publications/2001.html
UNSCEAR, 2006. United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and Effects of Ionizing Radiation. UNSCEAR 2006 Report Vol. I. Effects of Ionizing
Radiation. UNSCEAR 2006 Report Vol. I. Report to the General Assembly, with scientificannexes A and B.
http://www.unscear.org/unscear/en/publications/2006_1.html
USEPA, 1996. United States Environmental Protection Agency. Setting Standards for Safe
Drinking Water.
http://www.epa.gov/safewater/standard/setting.html
USEPA, 2000. United States Environmental Protection Agency. Radionuclides Notice of Data
Availability, Technical Support Document. Prepared by: USEPA Office of Ground Water andDrinking Water in collaboration with USEPA Office of Indoor Air and Radiation United States
Geological Survey. March, 2000.
http://yosemite.epa.gov/water/owrccatalog.nsf/e673c95b11602f2385256ae1007279fe/3a339e301
64b47a485256d83004fd9ac!OpenDocument
USEPA, 2001a. United States Environmental Protection Agency. User’s Guide: Radionuclide
Carcinogenicity. 2001.
http://www.epa.gov/radiation/heast/userguid.html#intended_users
USEPA, 2001b. United States Environmental Protection Agency. Radionuclide Table:
Radionuclide Carcinogenicity – Slope Factors (Federal Guidance Report No. 13 Morbidity Risk
Coefficients, in Units of Picocuries). 2001.
http://www.epa.gov/radiation/heast/docs/heast2_table_4-d2_0401.pdf
Page 53 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Walkerton, 2002. Part Two Report of the Walkerton Inquiry: A strategy for Safe Drinking
Water. The Honourable Dennis R. O’Connor.
http://www.attorneygeneral.jus.gov.on.ca/english/about/pubs/walkerton/part2/
WHO, 2004. World Health Organisation. Guidelines for Drinking-Water Quality. Vol. 1.
Third Edition. Geneva, Switzerland.
http://www.who.int/water_sanitation_health/dwq/GDWQ2004web.pdf

Page 54 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Appendices1. 1st Request for ODWAC Advice from the Minister of the Environment, February 21, 2007.
2. Request for Tritium Review from Toronto Medical Officer of Health, September 27, 2006.
3. 2nd Request for ODWAC Advice from the Minister of the Environment, June 12, 2007.
4. Ontario Hydro letter to Minister Wildman, December 9, 1994.
5. Canadian Nuclear Association letter dated April 23, 2008.
6. Toronto Public Health letter dated July 28, 2008.
7. Ontario Drinking Water Advisory Council - Public Consultation on the Ontario Drinking
Water Quality Standard for Tritium - March 26 and 27, 2008 Toronto, Ontario – Summary
Report – Prepared for the Ontario Drinking Water Advisory Council By Lura Consulting –June 5, 2008.

Page 55 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council – May 21, 2009

Page 56 of 56

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 1:
1st Request for ODWAC Advice from the Minister of the Environment,
February 21, 2007Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 2:
Request for Tritium Review from Toronto Medical Officer of Health,
September 27, 2006Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 3:
2nd Request for ODWAC Advice from the Minister of the Environment,
June 12, 2007

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 4:
Ontario Hydro letter to Minister Wildman, December 9, 1994

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 5:
Canadian Nuclear Association letter dated April 23, 2008

CNA Supplementary Submission to the Ontario Drinking Water Advisory Council
on the Review of the Limit for Tritium in Drinking Water – April 23, 2008
The responses and clarifications below are provided to the Ontario Drinking Water
Advisory Council (ODWAC) as a follow up to the Canadian Nuclear Association (CNA)
presentation during the public consultation of March 26 and 27. Some of the verbal
responses provided by Mr. Coupland and Dr. Hart of CNA were requested in writing by
ODWAC members. Clarifications and additional information that CNA believes willassist the council in their deliberations are also provided.
The questions that were posed by council members are paraphrased as:
1 a. Can you explain the differences between the chemical and radiologicalparadigms for setting limits for contaminants in drinking water?
1 b. Can you provide a scientific reason for why the council should not recommend
the use of a lifetime risk criterion of 10-6 to derive the drinking water standard
for tritium?
1 c. Can you provide the basis for the U.S. EPA dose criterion of 0.04 mSv/y fortritium in drinking water?
1 d. In countries where there exist two different standards for chemical andradiological contaminants in drinking water, was the decision to have 2
different standards a scientific one or a policy decision?
Before providing responses to these questions, a review of some background material isrequired.
BACKGROUND
These questions deal with the same fundamental issue that was raised by the Advisory
Council on Environmental Standards (ACES) report (ACES 1994), i.e. Should themethods for setting regulatory limits for chemical and radiological contaminants indrinking water be harmonized?
The harmonization issue was raised by the Science Advisory Board and the Radiation
Advisory Committee of U.S. Environmental Protection Agency (EPA) in the form of acommentary and a request to EPA’s Administrator in 1992 (EPA 1992) to address theissue in some way. Although they could not advise on how to achieve harmonization,
they did state that “Harmonization does not necessarily imply identical treatment, but it
does imply that any differences in treatment are clearly explained and justified.”
In 1995, Overy and Richardson, both from EPA, published an article in theEnvironmental Law Reporter (Overy 1995) on “current steps toward risk harmonization”
between radiological and chemical carcinogens. They concluded that “EPA’s radiation
standards, which in many cases were derived under policies applicable to chemical
carcinogens, are, for the most part, consistent with the International Commission on
Radiological Protection’s (ICRP’s) recommendations.”2

In 1998 Health Canada and the Atomic Energy Control Board (AECB, now the Canadian
Nuclear Safety Commission or CNSC) issued their report on the Assessment andManagement of Cancer Risks from Radiological and Chemical Hazards, an effort thatwas requested by the Ontario Minister of Environment and Energy to help resolve theissue that ACES raised (HC 1998). This report was developed by a joint working groupof staff from Health Canada, AECB, AECB’s Advisory Committee on RadiologicalProtection, AECB’S Group of Medical Advisors and a representative of the Ontario
ministry of Environment and Energy. They identified the similarities and differences inrisk assessment and risk management for radionuclides and for chemicals as well as thestrengths and weaknesses of each approach. They concluded that the risk management
strategies of both methods are well-developed and produce a high degree of healthprotection with actual exposures well below legal limits. They agreed harmonization of
the two methods could be desirable, but would not be practical at that time. They
recommended that future opportunities for harmonization should be considered, but indoing so, “consideration must be given as to whether public health benefits would bederived from harmonization.”
Duggan and Lambert, from the United Kingdom, published a paper in 1998 (Duggan
1998) comparing the approaches used for radiation and chemicals for environmental
standards. They cover basically the same similarities and differences as the publications
mentioned above, and suggest possible pathways to some degree of harmonization, but
conclude that the possibility of achievement of an integrated approach remains remote.
In 1976, EPA established a dose-based drinking water standard for combined beta andgamma emitting radionuclides (includes tritium) of 4 mrem per year (0.04 mSv/y). The
U.S. Safe Drinking Water Act was amended in 1986 and in 1996, The U.S. National
Primary Drinking Water Regulations (NPDWR) of 1977 were reviewed starting in 1991
with a final revision issued in 2000 (EPA 2000c). This included considerations ofharmonizing how genotoxic chemicals and radiological hazards are regulated. Other than
the article by Overy and Richardson mentioned above, there is no overt record of aformal evaluation of harmonization by the EPA, although considerable insight into EPA’s
direction in this respect can be obtained from the points raised by Overy and Richardson,
the Technical Support Document for radionuclide standards for the NPDWR revision of2000 (EPA 2000a), the Proposed Rule document (EPA 2000b) and the Final Rule (EPA
2000c). It appears that EPA has already harmonized how it regulates genotoxic
chemicals and radionuclides. The following derivation of radionuclide standards is very
similar to how chemical standards are derived. EPA clearly states that there is a range ofacceptable lifetime risk for contaminants in drinking water from 10-6 to 10-4, and that it
considers as appropriate a lifetime risk level of about 10-4 from radiological contaminants
mainly because of the precision of the risk data, but also because of the small fraction of
the population that actually is exposed to risks greater than 10-6 through the application ofemission controls. Thus it is starting from a lifetime acceptable risk criterion (whichhappens to be different from the one used for some chemicals – more on the rationale
later). EPA determined the tritium standard using a risk value that takes into accountage, gender and sensitive populations:

3

The U.S. EPA set the target risk level for beta and gamma emitting radionuclides at about
10-4 lifetime risk, and this falls within EPA’s acceptable risk range of about 10-6 to 10-4.
The tritium drinking water risk coefficient was calculated taking into account lifelong
ingestion of water (70 years), adjusted for age differences over a lifetime (e.g. intake
rates, physiological changes and sensitivities), and gender (EPA 1999). The associatedannual radiation dose (effective dose equivalent) is 0.04 mSv/y, assuming a constant
exposure concentration over a lifetime (EPA 2000a). Although a 1991 EPA
determination of the associated concentration limit (Maximum Contaminant Level, MCL)
gave a value of 2,253 Bq/L, the 1996 Safe Drinking Water Act Amendments do not allow
raising the limit above the previous 1976 value of 740 Bq/L, so this value remained as thetritium standard in the 2000 regulations . The value determined in 1976 used the ICRP 2(ICRP 1959)/NBS 69 (NBS 1963) dosimetry system, while the 1991 value wasdetermined using the current ICRP 60 dosimetry system (ICRP 1990).
Derivation of the tritium MCL in terms of activity concentration (i.e., pCi/L)
corresponding to a specified target risk level:
MCL (pCi/L) = TR/[(RF * 0.037) * 2 * 365 * 70)] = 60,900 pCi/L (or 2253 Bq/L)
where:
TR = target risk level (1.09x10-4 for beta and gamma emitters, including tritium, EPA
2000).
RF = tritium drinking water risk coefficient from Federal Guidance Report No. 13(EPA1999) = 9.44x10-13 Bq-1 in risk per Becquerel (Bq).
0.037 = factor to convert from Bq to pCi/L.
2* 365*70 = Litres of water consumed over a lifetime.
Although EPA used its own adjusted lifetime risk levels from Federal Guidance Report
No. 13, the basic radiological risk data is taken from ICRP/UNSCEAR sources.
UNSCEAR, the United Nations Scientific Committee on the Effects of Atomic Radiation
is an authoritative international body of experts on radiation effects.
The World Health Organization (WHO) approach for radiological contaminants indrinking water (WHO 2006) is similar to the EPA approach, whereby it states that its
dose criterion of 0.1 mSv/y corresponds to a lifetime risk of about 10-4 (actually 3.5 x 10-4
for fatal cancers). The WHO uses a risk criterion of 10-5 for non-threshold (genotoxic)
chemicals, but allows that individual national authorities may choose to use an alternativevalue between 10-6 and 10-4. Thus the WHO recommended regulation of radionuclides issimilar to that of the US EPA and to the regulation of genotoxic chemical carcinogens inboth the U.S. EPA and the WHO.
The main differences between the regulation of radiological and genotoxic chemicals
appear to be (1) the placement within the range of acceptable risk, and (2) the presence orlack of a combined risk criterion for multiple contaminants.

4
When the linear no-threshold model is assumed for regulatory purposes, the uses oflifetime risk, annual risk and radiation dose are essentially interchangeable (with proper
conversions) and do not represent any fundamental differences. EPA selected a lifetime
risk level of 10-4 for radiation as the upper bound of acceptable risk in the process ofresolving a court case in 1987 and based this conclusion on a Survey of Societal Risks
and their relative “acceptability.” (Overy and Richardson 1995). The lower bound of 10-6
did not have as direct a foundation, as it started out as zero (Delaney Clause) and worked
its way up to a more practical level of 10-6 over time. The EPA and the WHO provide arationale for the selection of a lifetime risk criterion of 10-4 as opposed to the level of 10-6
to 10-5 for genotoxic chemicals. They state that the upper level of the acceptable risk
range is appropriate because of the significantly better quality of risk-response data forradiation as compared with chemicals in general. Data for radiation effects and risk
have been derived over many years from both human epidemiological data as well asanimal studies. Duggan and Lambert state “There are more and better quality human
exposure risk data for radiation than for any other environmental carcinogen and this has
resulted in calculated risk estimates of apparently high precision”. These high quality
data have been reviewed and analyzed by authoritative scientific international bodies
such as UNSCEAR and ICRP and updated relatively frequently as more data become
available in order to produce the radiation risk estimates currently used by most countriesof the world, including Canada. Because of the much lower uncertainty in risk estimatesfrom exposure to radiation as opposed to chemicals, the “maximum acceptable risk” does
not have to be set as conservatively as for exposure to chemicals. In setting its lifetime
radiation criterion of 10-4, EPA also considered that the risk would not exceed 10-6 for thegreatest number of persons reasonably achievable through the application of emission
controls (source control). The same approach was taken for benzene in 1989 (Overy
1995). It should be noted that controls over (man made) sources of radionuclides indrinking water in Ontario are in the form of federal (CNSC) regulations, policies andlicense conditions which include the requirement to follow the ALARA principle foremissions (As Low As Reasonably Achievable, economic and social considerations being
taken into account). Although the CNSC emission limits do not explicitly consider thedrinking water standard for radionuclides, they have been sufficiently effective (becauseof the application of ALARA) to have kept drinking water exposures to the lifetime risk
level of 10-6 or lower. Consideration of the level of natural radiation background risk of
10-3 to 10-2 (assuming the Linear No Threshold model) and its geographic variability of
up to a factor of 10 as a benchmark to the acceptable maximum radiation risk level of 104
puts the risk of exposure to manmade radioactivity in drinking water in perspective, i.e.
regulating to levels somewhat lower than the variability in natural background.
The second difference between the chemical and radiological approach is that limits forchemicals are set individually at a lifetime risk of 10-6 or higher. The presence ofmultiple chemicals generally means that total lifetime risk to an individual consuming thedrinking water could be many times higher than 10-6, although for most chemicals it is
not known whether combined effects are linear, synergistic or antagonistic. The lifetime
risk of 10-4 for radionuclides (for WHO and Canada) applies to all radionuclides
collectively, such that only a portion of the calculated limit may be applied for eachradionuclide if more than one radionuclide is present, so that the total lifetime risk to the5individual does not exceed the risk/dose criterion. In the U.S., EPA made the dose/risk
criterion for beta and gamma emitters a combined one, but provided separate limits foruranium, radium, and alpha emitters (usually of natural origin). The combined limit onradionuclides is possible because of the increased level of knowledge of radiologicalrisks, such that a system was developed by ICRP that allows the dose/risk to variousorgans and tissues of the human body from exposure to different types of radiation to be
combined using weighting factors derived from epidemiological data, i.e. the “effective
dose” concept. There is no comparable system for most chemicals, so that the combined
risk from multiple chemicals can not be determined, while it can be for multiple
radionuclides.
Having presented this background material, answers to the questions posed at the start ofthis letter are:a) Although the methods for setting radiological and genotoxic chemical
contaminant limits in drinking water evolved separately and appear to be quite
different, current limits calculated by methods recommended by the WHO andthose derived by the US EPA are in fact very similar in nature for the two types ofcontaminants. Both types of contaminants now start with a maximum lifetime
risk in the acceptable range of about 10-6 to 10-4, apply the Linear No Thresholdassumption for risk at very low environmental concentrations, and derive amaximum concentration limit based on an assumed daily intake of drinking water.
Because of the much higher uncertainty in estimating risks for chemical genotoxic
carcinogens, a lifetime risk level of 10-6 is applied for determining the limits formany chemicals, while a risk of 10-4 is applied for determining the limits forradionuclides. Another consideration for the higher maximum risk forradionuclides is the assurance that the greatest number of persons reasonably
achievable will be exposed at a risk of about 10-6 through the application ofsource controls. The radionuclide risk criterion may also be expressed as anannual radiation dose, but this parameter is not independent of the lifetime risk
and the two are interchangeable with proper conversions. Chemicals are
regulated on an individual basis while radionuclides are regulated on a combined
basis. Thus a mixture of chemicals in drinking water, each with a risk of 10-6,
will have a higher total risk than 10-6, while any number of natural or man maderadionuclides in the drinking water would have a maximum risk of 10-4.
b) In addition to reasons given in the first answer, there appears to be no reason to
select a lifetime risk of 10-6 as the sole criterion for drinking water limits for allcontaminants. The two global leaders in setting/recommending drinking water
standards, US EPA and the WHO, allow for a range of acceptable lifetime risk
criteria of about 10-6 to 10-4, and provide reasonable rationales for setting theradiation criterion at 10-4, i.e. mainly the higher quality of radiation risk data, andalso the very low fraction of the population that is actually exposed to risks higher
than 10-6 as a result of emission controls. Note that in Ontario, a large fraction of
the population is exposed to tritium in drinking water, but an extremely low
fraction of the population may be exposed to lifetime risks greater than 10-6 fromtritium in the drinking water as a result of the application of emission controls.

6
The case for tritium is the same as for any other radionuclide since the stressor is
the radiation emitted from any radionuclide. There are no valid reasons to single
out tritium from all other radionuclides. Most claims of this nature made in the
recent non-peer-reviewed Greenpeace report on tritium hazards authored by Dr.
Fairlie have been refuted by the panel of scientific experts who attended thetritium risk workshop hosted by the CNSC in January 2008 in Ottawa (please see
the proceedings of this workshop), and by the response prepared by Dr. Richard
Osborne, a respected Canadian and international authority on tritium (Osborne
2008a, Osborne 2008b). The only issue raised that may affect the dose and thus
risk from tritium is the radiation weighting factor which could possibly result in
an increase in dose/risk of about a factor of 2. Perhaps the questions to be asked
are “what compelling reason would the council have to justify a departure fromthe well established, well thought-out, well reviewed, and still unchanged risk
criterion for the regulation of radionuclides in drinking water as implemented by
the US EPA, and as recommended by the WHO and implemented in most othercountries that have radiological limits or investigation levels in their drinking
water regulations?”, and “What benefit to public health would result?”c) As described above, the current basis for the 0.04 mSv/y dose limit used by the
EPA for tritium is tied to a lifetime risk of about 10-4 for lifelong exposure at theconcentration level associated with this dose. A concentration of 740 Bq/L oftritium was originally calculated using 1959 dosimetry models and parameters.
Although a 1991 recalculation gave 2,253 Bq/L using current dosimetry models
and parameters, U.S. law does not permit the lowering of the limit, so it remains
at 740 Bq/L in the latest revision of the US National Primary Drinking Water
Regulations. It should be noted that the total dose from radionuclides could besomewhat higher than 0.04mSv/y (or risk greater than 10-4) in some situations, as
the EPA combined dose limit is only for beta and gamma emitting radionuclides,and does not include separate limits for some natural radionuclides, i.e. uranium,
radium and alpha emitters. (The Ontario standard has a combined limit for all
radionuclides, both natural and man-made, so the dose limit of 0.1 mSv/y would
not be exceeded).
d) The differences in the risk criteria for radionuclides and for chemicals in the U.S.
and in those countries that base their regulations on the WHO drinking water
recommendations have a scientific rationale as described above. It should be
noted that the European Union (EU) countries who have adopted the EU Directive
for drinking water regulation do not have a limit for tritium, only an indicatorparameter level, more like an investigation level, not an action level. The EU also
has an indicator parameter for “total indicative dose” (the dose from allradionuclides combined) set at 0.1 mSv/y, consistent with the WHO
recommendations, but again, it appears as an investigation level in the EU
directive while it is a recommended standard in the WHO document.

7

2a.

What is the U.S. Environmental Protection Agency’s (EPA) basis for the 0.04
mSv/y dose criterion for setting radiological drinking water standards?
The basis for the 0.04 mSv/y EPA dose criterion is included in some detail in the
Background information above, and is summarized here.

The U.S. EPA set the target risk level for beta and gamma emitting radionuclides,
including tritium, at about 10-4 lifetime risk. This level is within EPA’s acceptable
range of risk of about 10-6 to 10-4. The risk coefficient for tritium was calculated
taking into account lifelong ingestion of water (70 years), and was adjusted for age
differences over a lifetime (e.g. intake rates, physiological changes andsensitivities), and gender (EPA 1999). The annual radiation dose that results fromthe 10-4 lifetime risk criterion is 0.04 mSv/y (EPA 2000a), and the associatedtritium concentration limit was 740 Bq/L, based on a previous dosimetry system(ICRP 1959, NBS 1963). A 1991 EPA recalculation of the associated concentration
limit based on the current dosimetry system (ICRP 1990) and 0.04 mSv/y dose gave
a value of 2,253 Bq/L of tritium. However, the 1996 Safe Drinking Water Act
Amendments do not allow raising the limit above the previous value of 740 Bq/L,
so this value remained as the tritium standard in the 2000 regulations. The basis forthe current limit is still the 10-4 lifetime risk.
2b.

What is the basis for the 0.1 mSv/y limit on radiological contaminants in drinking
water set by the World Health Organization (WHO)?

This dose/risk basis is adopted by many countries, including those of the European
Community. The WHO gives the following rationale for their basis for setting
limits for radiological contaminants (WHO 2006):“The current Guidelines are based on:—a recommended reference dose level (RDL) of the committed effective dose, equal
to 0.1mSv from 1 year’s consumption of drinking-water ....... and
The additional risk to health from exposure to an annual dose of 0.1mSv associatedwith the intake of radionuclides from drinking-water is considered to be low for thefollowing reasons:• The nominal probability coefficient for radiation-induced stochastic health effects,
which include fatal cancer, non-fatal cancer and severe hereditary effects(emphasis added) for the whole population, is 7.3 x10-2/Sv (ICRP, 1991).
Multiplying this by an RDL equal to 0.1mSv annual exposure via drinking-water
gives an estimated upper-bound lifetime risk of stochastic health effects ofapproximately 10-4, which can be considered small in comparison with many other
health risks. This reference risk estimation for radionuclides is quite reliable due tothe extensive scientific databases that have included human population exposuredata. As with chemical carcinogen risk extrapolations, the lower-bound risk is zero.
• Background radiation exposures vary widely across the Earth, but the average isabout 2.4mSv/year,with the highest local levels being up to 10 times higher without

8
any detected increased health risks from population studies; 0.1mSv therefore
represents a small addition to background levels.”
Further details related to the statements quoted above are available in WHO 2006.
2a and 2b – In summary, both the U.S. and the WHO set drinking water limits forradionuclides (with Uranium as an exception) on the basis of an acceptable risk fromexposure to the associated radioactivity, and they both use a lifetime risk of about 104. EPA states that this falls within their range of acceptable risks of about 10-6 to 10-4.
The WHO uses a lifetime risk basis of 10-5 for chemical genotoxic carcinogens, so
their range is 10-5 to 10-4. The EPA provide a rationale for setting the radiologicalrisk limit at about 10-4, i.e. the much better quality of risk data for exposure toradioactivity (and thus lower uncertainty than for most genotoxic chemicals), and theestimation that most of the population would be subject to an actual exposure risk ofaround 10-6. The WHO also provides a rationale as to why they went to the higher
end of the acceptable risk range for radioactivity, i.e. a) the lower uncertainty in thevalue of risk per unit radiation dose which is based on a large body of data including
human population exposures, and b) the observation that the limiting dose criterion(0.1 mSv/y) is a small fraction of the average background radiation level (2.4 mSv/y)and a small fraction of the variability of that background which ranges up to a factorof 10 higher than average, with no observed increases in health risk. Other thansetting a different level of acceptable risk for chemicals and for radioactivity, thedetermination of the radionuclide limits and the genotoxic chemical carcinogen limits
follow very similar methodologies.
3. Why was Dr. Osborne’s critique of Dr. Fairlie’s Greenpeace report not
published in a journal where Dr. Fairlie could have an opportunity to respond.
A member of the panel asked whether the commentary prepared by Dr. Richard
Osborne for the Canadian Nuclear Association on the report prepared for Greenpeace
by Dr. Ian Fairlie had been published, so that Dr. Fairlie would have an opportunity torespond. Neither Dr. Fairlie’s Greenpeace report nor Dr Osborne’s review has been
published in a peer-reviewed journal. The Greenpeace report was posted on theirwebsite (http://www.greenpeace.org/canada/en/documents-and-links/publications/),
and Dr. Osborne’s review on the CNA website (http://cna.ca/english/studies.asp).
Dr. Fairlie, however, has published a paper in a peer reviewed journal (Fairlie 2007)
which deals only with the question of the appropriate radiation weighting factor, anddoes not mention any of the other claims and concerns about tritium risk that hementioned in the Greenpeace Report. The wR issue has been thoroughly discussed in
the commentary by Dr. Osborne, and at the Canadian Nuclear Safety Commission(CNSC) January 2008 workshop (see proceedings of that workshop).

9
4. Please provide the wording in OPG’s ISO 14001 document about OPG’s 100
Bq/L voluntary commitment on tritium in drinking water.
Many presenters at the recent ODWAC public consultation on the review of thestandard for tritium in drinking water claimed that OPG’s ISO 14001 document
contained a statement that OPG would keep tritium in drinking water less than 100
Bq/L or that OPG “could now meet the 100 Bq/L level”. We are not sure how thepresenters obtained such information, but their statements are not correct. Our
Nuclear Program ISO 14001 document, “Environmental Management”, OPG
document N-PROG-OP-0006, does not contain any wording about keeping tritium indrinking water at 100 Bq/L. In 1994, the Ministry of the Environment recommended
7,000 Bq/L as the limit for tritium in drinking water, calculated by the traditional
radiological method. The Advisory Council on Environmental Standards (ACES
1994) issued their own recommendation of 100 Bq/L, going down to 20 Bq/L in 5
years, calculated according to their method for chemical contaminants. The Ontario
government set an interim standard for tritium in drinking water of 7,000 Bq/L,
pending the outcome of a federal study that they requested to examine differences
between the radiological and chemical approaches to setting drinking water standards
and to recommend a value for the standard. At that time, Ontario Hydro voluntarily
committed to the minister of the environment to maintain tritium releases from its
nuclear power plants at or below historic levels, consistent with its ALARA operating
practice, such that levels at nearby water supply plants would not exceed 100 Bq/L on
an annual average basis (OH 1994). Ontario Hydro and its successors, Ontario Power
Generation and Bruce Power continue to meet this commitment which is mentioned
in Ontario Power Generation’s and Bruce Power’s annual environmental monitoring
reports (e.g. OPG 2007, Bruce 2007).
5. Are there practical technologies available for the removal of tritium fromdrinking water?
The technology currently used by Ontario Power Generation in the Darlington
Tritium Removal Facility (TRF) for removal of tritium from contaminated water isdesigned for treating relatively higher concentrations of tritium in heavy water, and is
not designed for removing tritium at very low concentrations and high volumes. We
are not aware of any existing practical technology that could remove tritium fromdrinking water at levels closer to background, or any that could operate on the scaleof a water supply plant for a large population. Atomic Energy of Canada Limited andKinectrics Inc. have looked into a conceptual design for removing lower
concentration tritium from light water (e.g. groundwater), but their conceptual design
is still for concentrations much higher than found in water supplies (e.g. 37,000Bq/L), would reduce levels to the current US drinking water limit (740 Bq/L), andcould handle only 1x106 US Gal./year (Everatt 2006). It is possible that a system for
detritiating a water supply plant could be developed, but the size and cost is likely tobe prohibitive.

10
6a. What causes tritium spikes in NPP emissions to water and what technologies areused/available to prevent/reduce these spikes,
6b. If the drinking water limit were dropped to 20 Bq/L, what else has to be done toensure drinking water limits will not be exceeded, and what would the cost be,and
6c. If the limit drops to 20 Bq/L, what are the implications on other radionuclides orother radiological protection areas – identify and explain.
The term “spikes” could mean a number of things. In the context of this public
consultation, based on the comments made by presenters and the questions of council
members, the term “spikes” is taken to mean any tritium emissions to a lake or riverthat result in short term tritium concentrations at WSPs greater than 20 Bq/L. CNA
has already presented data showing that emissions from NPPs do not result in annual
average tritium concentrations greater than 20 Bq/L in WSPs. OPG experience overthe six year period 2000-2005 has been that at routine operational levels, with nospecific sources of higher than normal tritium emissions identified, weekly emissions
may reach about 15 Bq/L during the winter months when dilution in the lake isusually at its lowest. In a special study, OPG analyzed daily tritium samples from theOshawa WSP for the month of December 2005 and found that concentrations greaterthan 20 Bq/L occurred on 7 days that month, reaching levels of up to 28 Bq/L. The
maximum average weekly concentration in December 2005 was 16.7 Bq/L, and theaverage annual concentration in 2005 at the Oshawa WSP was 7.4 Bq/L.
Tritium waterborne emissions could be reduced in general by a more efficient leakdetection/leak repair program or by lowering the tritium concentration of heavy waterin the station systems so that the impact of any leak with respect to releases of tritium
is lower.
Improvements to the leak detection/leak repair program are already made every year
and are incremental, thus large reductions in emissions can not be expected from thisprogram without a significant change in approach. One approach currently possible
is the installation of tritium monitors on each reactor heat exchanger that has acapability of producing a leak containing a significant amount of tritium. This
arrangement would allow detection of a slowly developing leak much sooner andcould result in the reduction of the amount of tritium released to the lake. However, it
would not be effective for a leak that developed quickly. The cost of installing
additional monitors at Pickering was estimated to be about 10-15 M$ (and likely asimilar cost at other CANDU stations).
It may be possible to develop a practical technology to remove tritium from the liquid
wastes discharged through the Active Liquid Waste Management System (ALWMS),
but no such process is currently available, and it would not address any leaks that
result in tritium being discharged through the high volume service water pathways.
This approach to remove tritium is costly. We currently have no estimate for the costof developing and installing ALWMS tritium removal equipment.

11
Essentially, a significant reduction in waterborne tritium emissions would have tocome from the installation at each nuclear station of a tritium removal facility (TRF)
similar to the one at Darlington. This would reduce the tritium concentration in theheavy water of all station systems and equipment significantly, so that the same
volume of heavy water leakage would now release less tritium to the environment.
Although the Darlington TRF now treats tritiated water from Darlington, Pickeringand the Bruce reactors, its capacity is not large enough to achieve the required
reductions for a 20 Bq/L limit at all of these reactors. A very rough estimate of thecost of each new TRF is 350 – 450 M$.
If the drinking water standard for tritium were to be lowered to 20 Bq/L only because
a lifetime risk criterion of 10-6 was to be applied in deriving that standard, theremainder of the radionuclide standards would have to be revised downward by afactor of 350 as well. The stressor associated with tritium is the exposure toradiation, exactly the same stressor as for all other radionuclides (except for uranium
whose chemical toxicity exceeds its radiation toxicity). Tritium has no characteristics
that would justify assigning it a different risk level than the other radionuclides.
Since all radionuclide drinking water standards, including Ontario’s are combined
standards – i.e. the maximum allowable dose or risk is applied to all radionuclides
concurrently present in a water supply, the associated maximum acceptable dose to
the public would be 0.1 mSv/y / (7,000/20) = 2.9x10-4 mSv/y. This is in sharp
contrast to the federal public dose limit of 1 mSv/y and could raise public concern
about this discrepancy or about their radiation safety in other areas – e.g. nuclear
power plant operation, incidental dose (not the diagnostic dose) while visiting adental office or medical x-ray department, or incidental exposure while working in
non-nuclear occupations such as sewage treatment plants (where low levels ofradioactive material used in medical diagnostic tests are disposed.) The current
performance of Ontario’s nuclear power plants (NPPs) results in public doses that
range from about 0.001 to 0.005 mSv/y. These doses would be 3 to 15 times higher
than the allowable dose from drinking water if a standard of 20 Bq/L were set fortritium, and it would be likely that emissions from NPPs would have to be reduced
significantly in order to address public concerns about this situation (No cost estimate
available). It should be noted that it would take only 3 minutes of exposure to naturalradiation during an airplane flight to reach the 0.00029 mSv dose that would beobtained from drinking water for a full year at a concentration of 20 Bq/L.
Another possibility is that a lower de facto public radiation dose limit, as establishedby a lower drinking water limit, would have an effect on radiation workers who havehigher dose limits than members of the public (because their exposure is voluntary
and they derive direct monetary benefit from that exposure). However, even taking
that consideration into account, radiation worker dose limits have remained within arange of 10 to 20 times the public dose limits since 1959, and going to a multiple of
3,500 to 7,000 times the public limit may be a source of concern for radiation workers
and their families who may demand an equivalent reduction of 350 in their dose
limits. Should this occur, there would be impacts in many fields where radiation ispresent such that more workers would be needed to achieve the same amount of work12
as is done today, or very significant changes in work practices, technologies andequipment would be needed to meet much tighter radiation protection requirements.
A quick review of data in the Canadian dose registry indicates that areas significantly
affected would include nuclear power plants, uranium mines and mills, diagnostic
nuclear medicine technicians, physicians, and industrial radiographers.
In summary, the implications of lowering the tritium drinking water standard to 20
Bq/L are expected to be significant because such an action would indicate that
Ontario rejects the risk levels currently acceptable for exposure to radiationinternationally, and considers that that they should be lowered by a factor of 350.
The response given in item 1 above provides evidence that adoption of a risk level of
10-6 for radionuclides in drinking water is not appropriate, that a level of about 10-4 isappropriate and is used by most jurisdictions, and that the drinking water standard fortritium and all radionuclides need not be inconsistent with international radiation
protection standards.
7. Can you provide a summary of the analysis and data on validations/calibrations
you do on your Derived Release Limits (DRL) models?
DRL model predictions for OPG and Bruce Power stations were validated with fielddata and shown to be sufficiently accurate to be suitable for the calculation of DRLs,
particularly for the radionuclides which have the largest impact on dose to the public,i.e. tritium and carbon-14. A comprehensive validation exercise was completed aspart of the validation of the software which implements our conceptual environmental
pathways models. Concentrations in environmental media were predicted by themodels using measured emission rates from the station and compared with actual
measurements of environmental media from our routine radiological environmental
monitoring program. The model is designed to predict realistic concentrations inenvironmental media, and it then adds considerable conservatism into the calculationof radiation dose by using 95th percentile intake rates (e.g. air, water, food) andconservative exposure factors for external radiation. A summary of the results of thatstudy for well water and surface water is given below (OPG 2003a)
Tritium in Well Water
Pickering - of 11 wells tested, the model over-predicted tritium concentrations for 8,
with an average predicted to measured ratio of 18, and under-predicted 3 wells withan average predicted to measured ratio of 0.6.
Bruce – of 21 wells tested, 15 were predicted to have tritium below the detection level(3.7 Bq/L), and in all 15, tritium was not detectable. In the remaining 6 wells, themodel over predicted all 6 by an average predicted to measured ratio of 5.
Tritium in Surface Water
Of 5 water supply plants (WSP) near Ontario nuclear power stations, the model overpredicted tritium concentrations for 4 of them with an average predicted to measured
ratio of 1.7, while it under predicted at one WSP with an average predicted tomeasured ratio of 0.5.

13
8. What can be monitored routinely at a WSP?
OPG experience is given as an example, but experience at Bruce Power is very
similar. Currently, operators at the Harris, Horgan, Ajax, Whitby, Oshawa,
Bowmanville and Newcastle WSPs collect samples of raw water once per shift, andstore these on site for a period of one month. OPG collects these samples once amonth, creates a weekly composite for each WSP and analyzes them for tritium at its
low-level environmental radiological laboratory in Whitby. Gross beta-gamma
activity is analyzed on monthly composite samples. The tritium detection level is 4.5
Bq/L, and the WSP samples typically have levels around 4 to 15 Bq/L. If OPG wererequired to provide and report on daily analyses, it would mean adding additionalbuilding space, staff, equipment and purchased services with an incremental costestimated at about 1.6 M$ initial capital cost and 0.9 M$/year operating costs, for anannualized incremental cost of 1.1 M$/year.
Technology for the measurement of tritium online at the levels encountered at thewater supply plant is not available. OPG operates an on-line (automated frequent
batch analysis) instrument for measuring tritium in its reactor building service water
for the purpose of early detection and minimization of any tritium leaks. The
minimum detection limit for this equipment is about 3,700 Bq/L, and we are notaware of any that is more sensitive.

9. Clarification: Sensitivity of Embryo/Fetus and Implications on
spikes/monitoring frequency
The effects of ionizing radiation exposure of the embryo or fetus in utero have beenwell-studied, particularly because of the risks from diagnostic and therapeutic
medical exposures of potentially-pregnant patients. ICRP 2003 provides a detailed
recent review.
In brief, there are 4 responses of concern: failure to implant during the first ~10 days
after conception; developmental abnormalities from exposure during the embryonicperiod to 8 weeks after conception; impairment of neurological development fromexposure during the period 8-25 weeks after conception, leading to reduced mental
capacity; and carcinogenic risk throughout gestation. The first 3 of these responses
have well-demonstrated thresholds in dose of at least 100 mGy (=100 mSv fortritium), and below this dose no effects have been observed. This is more than 1000
times the maximum dose that could be received under the current Canadian drinking
water guideline. The risk of inducing a cancer is believed to persist throughout the
pregnancy, perhaps higher in the third trimester. This risk, however, is not different
from that of a child, which is perhaps a few times greater than that of an adult.
The issue of protection of the female fetus during the period of development ofoocytes was raised in the public consultation by many presenters in the context of theneed to have the drinking water standard provide adequate protection for a sensitive

14
segment of the population and in the context of a possible need for more frequentmonitoring of tritium in drinking water. The UK Advisory Group on Ionising
Radiation (AGIR) comprehensive review of the risks from tritium (AGIR 2007)
examined the risks from continuous exposure of oocytes to tritium from conception to
30 years of age. It concluded that for an equilibrium body content of tritium of 175
kBq, the frequency of severe hereditary effects would be expected to be about 10-6,
and this may be compared to a normal incidence of 3% to 4%. Continuous intake of
2 L of drinking water per day containing tritium at 7,000 Bq/L would result in an
equilibrium body content of about 200 kBq of tritium, and using the AGIR risk of 106
for 175 kBq, a risk of hereditary effects of about 1.1x10-6 would be expected.
Similarly, continuous intake of drinking water with 100 Bq/L of tritium produces arisk estimate of 0.016x10-6, and for 20 Bq/L tritium, the risk estimate is 0.003x10-6.
Thus continual consumption (at 2L/d) of drinking water with 7,000 Bq/L of tritiumor less represents a very low lifetime risk of hereditary effects via exposure ofoocytes, does not constitute a limiting case for setting the drinking water standard,
and does not support any increase in the frequency of monitoring in Ontario.
At doses below the annual public dose limit (1 mSv per year), there is no differencein risk for any of these effects whether the dose is distributed evenly over the year, or
received in a single day. For doses below this public dose limit, or at the Ontario
Provincial Liquid Emission Response action level (7,000 Bq/L at a WSP), there is nobenefit to risk management in monitoring drinking water on a daily or even a weekly
basis.
10. Clarification: Renfrew high tritium levels – still produced a very low dose.
During Ole Hendrickson’s presentation, he described a citizen of Pembroke whose
urine reportedly contained a concentration of HTO of 2000 Bq/L. Tritium in urine
accurately reflects its concentration in body water generally, and is used as the basis
for monitoring HTO-exposed workers. However a concentration of 2,000 Bq/L
corresponds to an annual dose, if maintained at this level throughout the year, of only
~ 0.04 mSv, a small fraction of the public dose limit, and of background.
11. Clarification : Misconceptions about credible evidence on Leukemia and birthdefects – references of proper epidemiological studies are provided.
Birth defects in populations living near the Pickering stations, and childhood
leukemias in populations living near all of the Ontario nuclear stations, have beenstudied by epidemiologists under contract to the CNSC (formerly the Atomic Energy
Control Board), by Health Canada and the Ontario Cancer Treatment and Research
Foundation, respectively. The birth defect results were reported in AECB 1991a. The
leukemia results were reported in AECB 1991b. Neither found statistically-significant
effects. These potential adverse health effects have also been considered by the
Durham Region Health Department (Durham 2007). They reported “In conclusion,disease rates in Ajax-Pickering and Clarington did not indicate a pattern to suggest

15that the Pickering NGS and the Darlington NGS were causing health effects in the
population.”
12. Provide information on HTO discharge rates, detection limit for monitoring at
the plant and corresponding WSP concentrations; time to reach WSP fromprevious leaks, and existence of reporting agreements and LERP (Liquid
Emission Response Procedures)
Routine tritium discharge rates from nuclear power plants (NPPs) are monitored andcontrolled at source as per CNSC regulations and license conditions. Although
CNSC limits are not set in terms of drinking water limits, CNSC requires its licensees
to apply ALARA. This has resulted in NPP discharges that are very low, and the
NPPs in Ontario have made a voluntary commitment to keep their tritium emissions
low enough so as not cause tritium in water supply plants to exceed 100 Bq/L on anannual average basis.
Non-routine tritium discharges from the NPPs have occurred in the past, mainly via aheat exchanger leak (equipment failure), and have released larger than routine levelsof tritium to the lake. The leaks are stopped at source generally within one shift.
Transit times to the closest WSP could be as little as a few hours (for maximum lake
current speeds) and as much as a few days, but elevated tritium levels persist at the
WSPs for periods from about a day to a few weeks. In response to such events, NPPs
have installed new or improved monitors in the discharge line of the reactor building
service water so that a leak can be detected and stopped much more quickly than in
the past, resulting in faster notification and lower tritium emissions. Furthermore, to
fulfill the Policy on Liquid Emission Response of the Province of Ontario Nuclear
Emergency Plan, nuclear power plant operators, OPG and Bruce Power, agreed tosend an abnormal waterborne tritium emission notification when tritium in the station
discharge would cause WSP levels to reach 600 to 2,000 Bq/L. Notification isprovided to Emergency Management Ontario, the Provincial Spills Action Centre andlocal municipalities (e.g. for OPG, it is to Durham Region and Toronto).
13. Clarification: on whether radiological dosimetry/risk takes into accountadditional sensitivity for women
ICRP 2006 provides detail on the methods recommended for ensuring that all
members of the public are adequately protected, regardless of age and sex. In short,the variations in radiation risk among these various populations are relatively wellknown, and as appropriate, the characteristics of the most sensitive members are usedas the basis of protection. The criterion for the representative person is generally that“the probability is less than 5% that a person drawn at random from the population
will receive a greater dose”.
In addition, the risk factors used by the US EPA for determining the drinking water
limit are taken from U.S. Federal Guidance Report No.13 (EPA 1999) and take into
account age, gender and sensitive populations adjusted over a 70 year lifetime.

16

REFERENCES
ACES 1994

A Standard for Tritium, A Recommendation to the Minister of theEnvironment and Energy, Advisory Committee on Environmental
Standards, ACES report 94-01, Ontario, May 1994.

AECB 1991aJohnson K.C. and Rouleau J., “Tritium Releases from the Pickering
Nuclear Generating Station and Birth Defects and Infant Mortality in
Nearby Communities 1971-1988” AECB INFO-0401 (1991).

AECB 1991b

Clarke E.A., McLaughlin J. and Anderson T.W. “Childhood Leukemia
around Canadian Nuclear Facilities Phase II – Final Report” AECB
INFO-0300-2 (1991).

AGIR 2007

Review of Risks from Tritium, Report of the Independent Advisory
Group on Ionising Radiation, Documents of the Health Protection
Agency, UK, November 2007.
Annual summary and assessment of environmental Radiological datafor 2006, B-REP-03419-00007 Rev 000, N. McDougall, April 11,
2007.

Bruce 2007

Duggan 1998

Standards for Environmental, Non-threshold, Carcinogens: A
comparison of the Approaches Used for Radiation and for Chemicals,
M.J. Duggan and B.E. Lambert, Annals of Occupational Hygiene, v.
42, No. 5, pp. 315-328, 1998.

Durham 2007

Durham Region Health Department 2007 publication, Radiation &Health in Durham Region: http://www.iicph.org/docs/health-durham2007.pdf .

EPA 1992

Letter from Dr. R.C.Loehr of the Science Advisory Board, and Dr.
O.F. Nygaard, Radiation Advisory Board to Hon. W.K. Reilly,
Administrator, U.S. Environmental Protection Agency, “Commentaryon Harmonizing Chemical and Radiation Risk-Reduction Strategies”,
EPA-SAB-RAC-COM-92-007, May 18, 1992.

EPA 1999

US EPA Federal Guidance No. 13, “Cancer Risk Coefficients forEnvironmental Exposure to Radionuclides”, EPA 402-R-99-001, Sep.
1999.

EPA 2000a

US EPA, “Radionuclides Notice of Data Availability, TechnicalSupport Document”, prepared by USEPA Office of Groundwater and17
Drinking Water in collaboration with USEPA Office of Indoor Air andRadiation, United States Geological Survey, March 2000.
EPA 2000b

National Primary Drinking Water Regulations; Radionuclides; Noticeof Data Availability; Proposed Rule, Part IV, Environmental
Protection Agency, Federal Register 40 CFR Parts 141 and 142, April
21, 2000.

EPA 2000c

National Primary Drinking Water Regulations; Radionuclides; Final
Rule, Part II, Environmental Protection Agency, Federal Register 40
CFR Parts 9, 141 and 142, December 7, 2000.

Everatt 2006

Technologies for Removal of Tritium from Water, A. Everatt, R.
Sadhankar, J.R. Robins, V. Singh, J.Krasznai, presented at the EPRI
2006 International Low Level Waste Conference, New Mexico, June
27-29, 2006.

Fairlie 2007

RBE and wR Values of Auger Emitters and Low-range Beta Emitterswith Particular Reference to Tritium, Journal of RadiologicalProtection 27 (2007) 157-168.

HC 1998

Assessment and Management of Cancer Risks from Radiological andChemical Hazards, prepared by a Joint Working Group assembled
from AECB’s Advisory Committees, AECB Staff, Health Canada
Staff, and Ontario Ministry of Environment and Energy Staff, 98EHD-216, AECB INFO-0684(E), AC-5, Canada 1998.

ICRP 1959

International Commission on Radiological Protection. Report ofCommittee II on Permissible Dose for Internal Radiation (1959). ICRP
Publication 2. New York: Pergamon, Adopted July 1959.

ICRP 1990

ICRP Publication 60: 1990 Recommendations Of The International
Commission On Radiological Protection, Annals of the ICRP Volume
21/1-3, Publication April 1991.

ICRP 2003

ICRP Publication 90, “Biological Effects after Prenatal Irradiation(Embryo and Fetus)” Annals of the ICRP 331-2 (2003).

ICRP 2006

ICRP Publication 101 “Assessing Dose of the Representative Person
for the Purpose of Radiation Protection of the Public and the
Optimisation of Radiological Protection: Broadening the Process”(2006).

NBS 1963

U.S. National Bureau of Standards. Maximum permissible bodyburdens and maximum permissible concentrations of radionuclides in18
air and in water for occupational exposure. National Bureau ofStandards handbook 69, as amended. AFP-160-6-7. Washington, DC:
Govt. Print. Office; U.S. Department of Commerce, August 1963. First
published in 1959, with an addendum in 1963. Also bears the series
title NCRP report no. 22, of the National Committee on Radiation
Protection and Measurements.
OH 1994

Letter O.A. Kupcis of Ontario Hydro to C.J. Wildman, Minister ofEnvironment and Energy, December 9, 1994.

OPG 2003a

IMPACT Validation Exercise Report , OPG Document N-REP-0348210006, April 2003.

OPG 2003b

The Pickering Model Verification Report for the Updated Radiological
Environmental Monitoring Program, OPG Report N-REP-0348110001, Lamarre, J. and Polack A., Dec.2003

OPG 2007

2006 Results of Radiological Environmental Monitoring Programs,
OPG report N-REP-03481-10005-R001, J. Borromeo, Dec. 2007.

Osborne 2008a

Review of the Greenpeace report: “Tritium Hazard Report: Pollution
and Radiation Risk from Canadian Nuclear Facilities” I. Fairlie, 2007
June by R.V. Osborne, Ranasara Consultants Inc., Deep River,
Ontario. Prepared for the Canadian Nuclear Association, 2007 August
13, Canadian Nuclear Association website at(http://www.cna.ca/english/studies.asp).

Osborne 2008b

Comments on the Ontario Drinking Water Quality Standard for
Tritium, Richard V. Osborne, PO Box 1116, Deep River, Ontario
K0J1P0 2008 March 7 (written submission to ODWAC)

ODWAC Supplement-Att. 1

19

4/23/2008

Overy 1995

Regulation of Radiological and Chemical Carcinogens: Current Steps Toward
Risk Harmonization, D.P. Overy and A.C.B. Richardson, The Environmental
Law Reporter, V.XXV, No.12, pp. 10657-10670, 1995.

WHO 2006

Guidelines for Drinking-Water Quality, First Addendum To Third Edition,
Volume 1, Recommendations- 3rd edition, World Health Organization, 2006.

Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 6:
Toronto Public Health letter dated July 28, 2008Report and Advice on the Ontario Drinking Water Quality Standard for Tritium
Ontario Drinking Water Advisory Council

Appendix 7:
Ontario Drinking Water Advisory Council - Public Consultation on the
Ontario Drinking Water Quality Standard for Tritium - March 26 and 27, 2008
Toronto, Ontario – Summary Report – Prepared for the Ontario Drinking
Water Advisory Council By Lura Consulting – June 5, 2008

Ontario Drinking Water
Advisory Council
Public Consultation on the
Ontario Drinking Water
Quality Standard for Tritium
March 26 and 27, 2008
Toronto, Ontario

Summary Report
Prepared for the
Ontario Drinking Water Advisory Council
By Lura Consulting
June 5, 2008
t: 416.410.3888· f: 416.536.3453 · www.lura.ca
515 Consumers Road - Suite 201
Toronto, Ontario M2J 4Z2, Canada

PUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORTThis public consultation summary was prepared by Lura Consulting. It presents a summary of the
public consultation meeting on March 26 and 27, 2008 and of received submissions. If you have any
questions or comments regarding the report, please contact either:
Scott Barrett
Executive AssistantOntario Drinking Water Advisory Council
Phone: 416-212-7596
scott.barrett@ontario.ca

ORJean-Louis Gaudet
Consultant
Lura Consulting
Phone: 416-410-3888 x5
jgaudet@lura.ca

PUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

Table of Contents

1

Introduction .......................................................................................................................... 1
1.1 About the Public Consultation Meeting........................................................................... 1
1.2 Overview of this Report .................................................................................................... 1

2

Summary of Public Comments.............................................................................................2
2.1 Is the current Ontario Drinking Water Quality Standard for Tritium acceptable? .........2
2.2 What is the basis for finding the current standard acceptable or unacceptable? ............2
2.2.1 Rationale for the standard being “unacceptable” ...................................................................2
2.2.2 Rationale for the standard being “acceptable”........................................................................5
2.3 If you propose a different Standard, what is your rationale?............................................5
2.4 Other Tritium-Related Comments ...................................................................................63

Next Steps .............................................................................................................................7

Appendix A: Meeting Agenda
Appendix B: Summary of Meeting Question and Answer Sessions
Appendix C: Meeting Presentations
Appendix D: Written Submissions

Summary ReportiPUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

ii

Summary ReportPUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

1 Introduction
1.1

About the Public Consultation Meeting

On March 26 and 27, 2008, the Ontario Drinking Water Advisory Council (ODWAC) held a twoday public consultation meeting on Ontario’s Drinking Water Quality Standard (ODWQS) for
tritium. The purpose of the meeting was to obtain input from a broad spectrum of interested
community groups and stakeholders. Consultation participants were asked for their feedback on thefollowing three questions:•••

Is the current Ontario Drinking Water Quality Standard for tritium acceptable?
If not, what is the basis for finding the current Standard unacceptable?
If you propose a different Standard, what is your rationale?

Participants were also invited to contribute any other feedback they had on the ODWQS for tritium.
This feedback will be incorporated with other input received to date from other stakeholders andwill inform ODWAC’s advice to the Ontario Minister of the Environment on this topic.
The Minister’s request for advice on this Standard was formally made to ODWAC on February 21,
2007. The request was in response to a letter from Dr. David McKeown, Medical Officer of Health,City of Toronto, which outlined concerns about the current Standard for tritium. The Minister’s
request asked ODWAC to consider the 1994 recommendations made by the former Ontario
Advisory Committee on Environmental Standards as well as the Greenpeace report entitled“Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities.”
The public consultation was advertised in the Toronto Star, and invitations were distributed directly
to stakeholder groups. Information on the consultation was also posted on ODWAC’s website at(http://www.odwac.gov.on.ca/standards_review/tritium/tritium.htm). The public was invited tomake a presentation to ODWAC at the meeting, to submit comments in writing, or both. At themeeting, participants were provided with 10 minutes to make their presentation, and an additional 5
minutes for questions from ODWAC panel members.
1.2

Overview of this Report

This report provides a summary of the feedback received through the public consultation, including
presentations made during the March 26-27, 2008 meeting as well as written submissions received ator following the consultation meeting.
The summary of public comments is provided in section 2 of this report and is organized based on
the three questions posed by ODWAC. The agenda for the meeting is provide in Appendix A, and asummary of the questions asked by the ODWAC panel members and the answers given by thepresenters is provided in Appendix B. Copies of the presentations and written submissions areprovided in Appendix C and D.

Summary Report

1PUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

2 Summary of Public Comments
This section provides a summary of the comments made by the presenters during the two-day
public consultation meeting and from the written submissions received during the consultative
process. A total of 65 individuals and organizations participated in the consultation, either by making
a presentation to ODWAC, submitting written comments, or both. Participants included:
•
•
•
•
•
•
•
•
•
•

19 individuals;
11 community-based groups;
8 health organizations (6 health non-governmental organizations and 2 professional
health associations)
6 environmental non-governmental organizations;
5 industry/consulting organizations;
4 municipalities;
3 non-governmental organizations;
2 universities;
1 federal government representative; and1 labour organization.

In addition, ODWAC received 532 e-mails from individual members of the public that closely
followed a model submission provided on the Greenpeace website.
The paragraphs below summarize the feedback provided by the various stakeholder groups. The
comments are organized according to the three key questions posed by ODWAC for this public
consultation, followed by a summary of any other tritium-related concerns or issues raised. No
attempt has been made to assess the scientific accuracy or basis of the feedback received.
2.1

Is the current Ontario Drinking Water Quality Standard for Tritium
acceptable?

In general, most of the stakeholder groups that commented during the Council’s consultation on theODWQS for tritium believe that the current Standard is not acceptable. These groups included
concerned citizens, community groups, health organizations, health non-governmental organizations
and professional health associations, environmental non-governmental organizations, municipalities,
non-governmental organizations, universities, and labour.
Five submissions indicated that the current standard is acceptable or that there is insufficientevidence to warrant lowering it (Health Canada, the Canadian Nuclear Association, two radiation
researchers/scientists, and a health physicist.).
2.2

What is the basis for finding the current standard acceptable orunacceptable?

2.2.1

Rationale for the standard being “unacceptable”

There were a number of issues raised to support the view that the current ODWQS for tritium is
unacceptable. These issues are summarized below.
2

Summary ReportPUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

Impact of Tritium on Human Health
The rationale provided by those who felt that the Standard is unacceptable was consistent across
many of the participants. A key area of concern was the potential impact of tritium on humanhealth. Key comments presented included:
•
•
•
•
•
•

There is no safe dose of or level to exposure of radiation, and even the smallest doses(e.g., background) can cause cancer and other heath effects. Tritium can also promote
and accelerate cancer.
Women are more vulnerable to tritium and are affected differently than men, particularly
with respect to their reproductive systems.
Rapidly growing cells such as fetal tissue and young girls’ developing breasts, genetic
materials and blood forming organs are especially sensitive to tritium.
Tritium can damage DNA, causing a mutagenic effect resulting in cancers, miscarriages,
birth defects, sterility, and hypothyroidism, among others. The effects from exposure totritium can harm offspring and last for generations.
Female human infants are at risk from elevated tritium levels due to genetic damage to
ova exposed to tritiated hydrogen.
Certain groups are especially vulnerable to environmental carcinogens, such as women(especially when pregnant), the unborn, and the elderly, those with compromised
immune systems, children, teenagers and Aboriginal people.

Risk and Dose Measurement Methodologies
Concerns about how risk and doses are measured and used to help set the Standard were raised bycommunity groups, citizens, NGOs and health organizations. These concerns included:
•

•
•

•
•
•

How risk and dose measurements are calculated, particularly in that the current models
use the “standard man”, which may not reflect dosages experienced by women andchildren. Research by Dr. Richard B. Richardson was cited as finding that the dosage oftritium to women is estimated to be 45% higher than the dose to the “standard man.”
Dr. Richardson’s research was referenced as illustrating that the dose co-efficient for
women is under-calculated.
Additionally, exposure studies based on animal testing are not accurate because of thelower body fat levels found in animals.
Many of the non-lethal cancer effects of tritium are not currently considered in themodel upon which the current Standard is based on. These effects include non-fatal
cancers, miscarriages, still births, birth defects, sterility, hypothyroidism, genetic
mutation, respiratory failure, kidney failure, nervous system disorders, cardiovasculardisease, among others.
The current Standard does not consider organically-bound tritium, thus under-estimating
the true dose.
Cumulative exposure and combined effects are not being considered.
The current Standard considers 340 excess fatal cancers per million as an “acceptablerisk”, which is equivalent to 1 in 3,000.

Summary Report3PUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORTWith respect to using either radiological or chemical assessment approaches in developing an
ODWQS for tritium, the Public Health sector advocated using the chemical-based approach. Theirreasons included:••••

The Standard is being set for drinking water for the whole population.
Tritium exposure should be considered primarily an anthropogenic contaminant emitted
to the environment.
Anthropogenic emissions of tritium directly impact the drinking water supplies ofapproximately one-quarter of the Canadian population, thereby resulting in a large
population exposure.
Exposure to tritium in drinking water is involuntary.

Tritium in Ontario’s Environment
Concern over the amount of tritium currently found in Ontario’s environment was cited as a reason
for the current ODWQS for tritium being unacceptable. For example, a few NGOs and community
groups noted that:••

Levels of tritium are 2 to 5 times higher in Lake Ontario than in other water bodies in
the Great Lakes and across Canada. For example, concentration of tritium in Lake
Ontario was reported to be 7.1 Bq/L, compared to 2 Bq/L in Lake Superior. Lake
Ontario is a major source of drinking water for Ontarians.
Between 1979 and 1997, there were 11 known leaks of tritium from Canadian nuclear
reactors.

Elevated concentrations of tritium were also reported to have been found in food and well water
samples. For example, water samples taken from a pond at a home in/near Millbrook in 2005 werereported to show an average concentration of 1770 Bq/L, with a maximum of 2494 Bq/L. The
home was reported to be 220 metres away from an emissions stack at a tritium light manufacturing
facility. Produce grown by residents in Pembrooke was reported to contain tritium levels as high as
12,000 Bq/L.

Proximity of Nuclear Reactors in Southern Ontario
A number of citizens, community groups, NGOs and health organizations, as well as the City of
Pickering, noted that Ontario has a high number of nuclear reactors that use heavy water as acoolant, and therefore the risk of exposure to tritium is higher due to the facilities proximity andtheir use of deuterium.

How the Ontario Standard Compares to Other Standards Internationally
Community groups, concerned citizens, NGOs, health groups and university representatives believethat Canada’s current Guideline for tritium in drinking water (which is the same as Ontario’s
Standard) is unacceptable because it is high compared to other jurisdictions. For example, while theODWQS for tritium is 7000 Bq/L, it was reported that the drinking water standard for tritium in
the United States is 740 Bq/L and the European Union has an action level of 100 Bq/L.

4

Summary ReportPUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORTThe Precautionary Approach
The precautionary approach was raised by many of the stakeholders who believe the current
Standard is unacceptable, including community groups, citizens, health organizations, and NGOs. It
was felt that the precautionary approach was not being applied with respect to tritium in drinking
water and that because there is still uncertainty over the impacts of tritium (such as synergistic
effects with other substances), then the precautionary principle should be applied and the Standard
should be lowered.
2.2.2

Rationale for the standard being “acceptable”

While many of the consultation participants felt that the current Standard was unacceptable, there
was some support not changing it. Reasons for not changing the current standard include:
•
•
•
•
•

There is no new information that warrants a change to the current Standard.
The methodology for assessing risk and dose for tritium and other radionuclides isinternationally accepted, sufficient and prudent;
The risk of fatal and non-fatal cancers from exposure to radionuclides in drinking water of
0.1 mSv/year is negligible (6 x10-4 over a lifetime).
Making the Standard more stringent would depart from international guidance and advice
from organizations such as the International Commission on Radiation Protection (ICRP)
and the World Health Organization (WHO).
Changing the Standard would create the false impression with the public that there is now ahigher risk from tritium in drinking water.

Also, regarding the question on whether to assess the risk from tritium as either ionizing radiation oras a genotoxic chemical, it was suggested that the appropriate assessment is as an ionizing radiation
because it is the location of where the radiation is delivered and the nature of the radiation that is
important, rather than the chemical nature of the radionuclides. It was also suggested that, for the
purposes of setting standards, all radionuclides should be treated equally.
It was also noted by one submitter that while there was currently no compelling reason to reconsider
the Standard at this time, it may be reasonable to adjust the radiation weighting factor from 1 to 2
and accommodate parameters more appropriate for infants, which would result in a revised Standardof 3,000 Bq/L. The submitter noted that adopting this value would be of little practical significancebecause tritium levels currently observed are already far below this value.
2.3

If you propose a different Standard, what is your rationale?

The majority of those who believe that the current ODWQS for tritium is unacceptable suggest thatthe levels proposed in the 1994 ACES report should be adopted, that the current Standard be
reduced immediately to 100 Bq/L and then to 20 Bq/L within 5 years. The main reasons stated for
adopting this process include:••

The ACES recommendation is more conservative than the current Standard;
Ontario Power Generation has stated that levels below 100 Bq/L at drinking water plantintakes are currently achievable;

Summary Report5PUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT•••

It employs the precautionary approach, and encourages erring on the side of caution;
It is based on the chemical genotoxic paradigm, rather than the radionuclide paradigm;
It lowers the level of risk of cancer to 1 in a million, and reduces the number of premature
deaths from 340 per million to 5 per million.

For similar reasons, some concerned citizens and NGOs recommended lower limits, ranging from 0
Bq/L to a range between 10 and 20 Bq/L.
2.4

Other Tritium-Related Comments

In addition to comments regarding the ODWQS for tritium, the consultation participants also
provided additional comments with respect to tritium. The most common of these was thesuggestion that the allowable level of tritium in discharge from nuclear reactors be zero. This
comment was made by health, NGO, municipal public health representatives, concerned citizens
and community groups. Other comments are summarized below.

Tritium and Human Health•••More research is needed to identify the impacts of tritium on human health.
A study is currently underway by the CNSC regarding tritium and its health impacts.
A committee should be established to investigate health issues related to tritium.

Tritium Monitoring•••

Monitoring for tritium in drinking water should be mandatory.
Should drinking water monitoring show levels of tritium higher than the maximum
allowable, then alternate drinking water supplies should be provided.
Daily monitoring of drinking water should be required for areas near Ontario Power
Generation (OPG) plants.

Public Notification and Disclosure•••

The public should be immediately notified when tritium levels in drinking water exceed 5
Bq/L.
The public and municipalities should be notified in instances of accidental releases of tritiumfrom nuclear facilities.
The nuclear industry should be compelled by stricter disclosure obligations.

Nuclear Power••

6

Government funds and subsidies should be diverted from nuclear power to renewableenergy;More research is needed on how to reduce emissions of radioactive material from nuclear
energy production facilities.

Summary ReportPUBLIC CONSULTATION ON THE ONTARIO DRINKING WATER QUALITY STANDARD FOR TRITIUM
SUMMARY REPORT

3 Next Steps
After the public consultation meeting, participants were given until April 4, 2008 to submit
additional comments for the consultation. Mr Jim Merritt, ODWAC Chair, noted that information
received after that date would still be considered in their advice to the Minister of the Environment.
ODWAC plans to transmit its recommendations on the ODWQS for tritium some time in thesummer of 2008.

Summary Report7