FAQ - Tritium Activity in Garden Produce from Pembroke in 2007 and Dose to the Public

Q1. What is tritium?
Q2. What is the Tritium Studies Project?
Q3. What is this report about?
Q4. How was a “long-term source of tritium” removed?
Q5. What does the study conclude?
Q6. What are the acceptable dose limits of tritium in Canada?
Q7. Is there a health risk related to the levels of tritium in the garden produce studied?

Q1. What is tritium?

A1. Tritium is a radioactive form of hydrogen that occurs both naturally and as a by-product in nuclear reactors and tritium processing facilities. Tritium exposure can pose a health risk if it is ingested through drinking water or food, inhaled or absorbed through the skin.  Releases of tritium by nuclear reactors and tritium processing facilities are regulated by the CNSC to ensure the health and safety of workers and the public, and the protection of the environment.

Q2. What is the Tritium Studies Project?

A2. In January 2007, the Commission Tribunal directed CNSC staff to initiate research studies on tritium releases in Canada, and to study and evaluate tritium processing facilities exercising the best practices around the globe.  In response, the CNSC has undertaken several research projects under the banner of the Tritium Studies Project. This research will enhance the information used in the regulatory oversight of tritium processing and tritium releases in Canada.

Q3. What is this report about?

A3. The Tritium Activity in Garden Produce from Pembroke in 2007 and Dose to the Public report provides results of CNSC-funded research at the University of Ottawa on tritium in garden vegetables and fruits in Pembroke, and a few matching soils collected in late summer 2007. The objective was to document how the local environment recovered when a long-term source of tritium was removed. Dose estimates for people consuming local produce are also provided for interpretation.

Q4. How was a “long-term source of tritium” removed?

A4. SRB Technologies (SRBT) in Pembroke is a CNSC licensee who has been producing tritium light sources since 1991. As a result of CNSC compliance enforcement actions, it temporarily ceased processing in 2007. This resulted in a large reduction in atmospheric releases relative to past operations and created a unique opportunity to study how the environment would respond to this reduction. Similar produce data were collected by CNSC staff in 2005, providing a suitable point of comparison for this investigation.

Q5. What does the study conclude?

A5.

• Tritium dose to the public in 2007 from the consumption of local Pembroke produce was less than 0.004 mSv per year. This is well below the public dose limit of 1 mSv per year and several orders of magnitude below doses known to cause health effects.
• This study found expected levels of tritium in local garden produce grown in Pembroke in 2005 and 2007.
• There was no evidence for significant accumulation of tritium in surface soils in 2007 after 16 years of tritium releases from the SRBT facility.
• The dose resulting from the consumption of tritium in fruits and vegetables grown in Pembroke declines considerably with increasing distance of gardens from the SRBT facility.
• Health risks in people exposed chronically to radiation doses of approximately 100 mSv or less cannot be distinguished from similar health risks in the general Canadian population.

Q6. What are the acceptable dose limits of tritium in Canada?

A6. The CNSC regulates nuclear facilities to protect health and the environment, and specifies dose limits from exposure to all sources of radiation from CNSC licensed activities, including tritium.

• For the general public, the dose limit is 1 milliSievert (mSv) per year.
• For nuclear energy workers, the dose limit is 50 mSv per year and 100 mSv over 5 years. 

Q7. Is there a health risk related to the levels of tritium in the garden produce studied?

A7. No. The highest tritium dose to the public in 2007 from the consumption of local Pembroke produce was less than 0.004 mSv per year. This is well below the public dose limit of 1 mSv per year and several orders of magnitude below doses known to cause health effects.