Canadian Guidelines allow nearly 10 Times more
Radioactive Tritium in Drinking Water
than is allowed under US Regulated Limits
INVERHURON, Ontario — October 7, 2002
Canadian guidelines for concentrations of radioactive “tritium” in drinking water are almost 10 times higher than the regulatory limits set by U-S authorities.
Health Canada’s Guidelines for Drinking Water Quality establishes a benchmark for the maximum level of tritium in drinking water at 7,000 becquerels per litre (Bq/L). The U-S Environmental Protection Agency’s (EPA) Safe Drinking Water Act establishes the regulated maximum limit at 740 Bq/L.
A becquerel is an international unit of measurement of the activity of a radioactive nuclide.
The Great Lakes supply drinking water to population centers in both the U-S and Canada. For example, Detroit, Michigan and London, Ontario are among many cities, towns and villages on both sides of the border which take their drinking water from Lake Huron. Plans for more pipelines to carry water from Lake Huron to Ontario cities have just been announced. (The world’s largest combined nuclear power generation and nuclear waste storage facility, the Bruce nuclear site, is situated on the Ontario shoreline of Lake Huron, 80 kilometers — 50 miles– from the Michigan shoreline.)
Tritium is a radioactive form of hydrogen with a half-life of 12 years. It is classified by the U-S EPA as a human carcinogen, and in addition to being a potential cancer causing agent, is suspected to be highly effective in mutating genes, promoting hereditary defects, and causing malformations in embryos and fetuses. It is implicated in contributing to childhood leukemia and Down’s Syndrome.
Less than 1% of the tritium in our environment occurs naturally. Tritium is used commercially in flares and illuminated watch dials. Decades of thermonuclear weapons testing starting in the early 1940’s resulted in tritium being released into the earth’s atmosphere. Tritium is also released to the environment during the production of nuclear energy.
Tritium and CANDU reactors
Canadian made CANDU reactors represent the largest point source of tritium in Canada. The reactors use “heavy water” as both a moderator and a coolant. Tritium is produced in large quantities in irradiated heavy water during the nuclear fission process.
Ontario Power Generation (OPG) owns 20 CANDU reactors: 8 are at the Bruce nuclear complex on the Lake Huron shoreline, and 12 reactors are on the shoreline of Lake Ontario at Pickering and Darlington nuclear stations.
According to the records of both OPG and the regulator, CANDU reactors discharge tritium into Lakes Huron and Ontario on a regular basis during routine operations and on many occasions through “unplanned emissions”. Canadian federal regulators allow discharges of tritium well in excess of national safe drinking water standards, based on the dilution effect that occurs when “tritiated” water mixes with lake water. It is from this mixture that officials obtain “derived emission limits”.
In one notable accidental release of tritium into Lake Huron from the Bruce plant, concentrations of tritium in drinking water at Port Elgin, Ontario (a town 15 miles north of the plant) reached more than two times the U-S EPA limit. (The incident also pointed out inadequacies in the notification and action protocols, and resulted in an agreement between plant and provincial health officials to strengthen and formalize procedures for notifying nearby Canadian municipal water supply plants.)
Recommended Changes to Limits Rejected by Ontario Government
In 1994, the Ontario government appointed Advisory Committee on Environmental Standards recommended that the maximum permissible concentration of tritium in drinking water be immediately reduced 70 fold to 100 Bq/L, and gradually dropped to 20 Bq/L over 5 years. Their recommendations were contained in a report called “A Standard for Tritium: A Recommendation to the Minister of the Environment and Energy”.
The recommendations were rejected by the government of the day.
The International Joint Commission, created by the 1909 Boundary Waters Treaty between Canada and the United States, has identified tritium as a persistent toxic substance, and a candidate for zero discharge.
The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has noted that Canadian CANDU heavy water reactors generate about 30 times the amount of tritium of a U-S light water reactor.
According to UNSCEAR, a CANDU reactor also normally releases over 20 times the amount of tritium to the environment as compared to a U-S light water reactor.
Using estimates from the International Commission on Radiological Protection and the World Health Organization, and assuming additive doses over a 70-year life span, lifetime exposure to the Canadian tritium standard for drinking water would cause 340 excess fatal cancers per million people, or just less than 1 in 3,000. This estimate does not include non-fatal cancers or potential hereditary defects.
A primer on tritum and a set of detailed notes comparing U-S and Canadian tritium standards for drinking water can be found on our web site [find this document]