[NukeNet] Danger of tritium exposure underrated, report says

[Diane Farsetta]

http://www.theglobeandmail.com/servlet/story/RTGAM. 
20070612.wtritium12/BNStory/National/home

Danger of tritium exposure underrated, report says
But regulators insist radioactive substance found in lakes near  
reactors is not a health risk

MARTIN MITTELSTAEDT
 From Tuesday's Globe and Mail
June 12, 2007 at 2:03 AM EDT


Releases of radioactive tritium from Canadian nuclear power plants  
are so elevated that children under 4 and pregnant women shouldn't  
live within 10 kilometres of an atomic generating station, and those  
living within five kilometres shouldn't eat food grown in their  
gardens, Greenpeace says in a controversial study being released  
Tuesday.

Canadian-style Candu reactors are among the world's largest sources  
of tritium, producing up to hundreds of times more of the radioactive  
substance than other reactor designs. The report says high amounts of  
tritium in the Great Lakes and around the stations indicate nuclear  
plants routinely emit it into the environment.

The Greenpeace report calls Health Canada's standard for the level of  
tritium in drinking water “very lax” because it is about 10 times  
higher than that of the United States and 100 times higher than the  
level allowed in Europe.

“Scientific concerns about tritium's hazards are inadequately  
recognized by Canada's nuclear regulators,” the study contends.

But federal regulators insisted Monday that tritium emissions  
shouldn't cause any concerns. The Canadian Nuclear Safety Commission  
said in a e-mail statement that tritium levels around atomic sites  
aren't a health threat and that the public “has not been exposed to  
unreasonable risk” from the consumption of fruits and vegetables  
grown near any facility. However, the commission said in January that  
its staff would study tritium emissions.

Most of Canada's nuclear power stations, located in Ontario, Quebec  
and New Brunswick, are in thinly populated rural areas, but the  
Pickering plant on the shore of Lake Ontario lies just outside of  
Toronto, and thousands of people live near it.

Greenpeace is the second influential entity to raise concerns about  
Canada's tritium standards recently. Last September, the Toronto  
Board of Health said it considered the drinking water standard out of  
date and it urged that it be tightened.

The Greenpeace study was written by Ian Fairlie, a British radiation  
expert who worked on a British government committee set up in 2001 to  
review the safety of tritium and several other radioactive  
substances. Earlier this year, he published a peer-reviewed journal  
article that concluded tritium's hazards are being underestimated.

Tritium, and the risk it poses, is among the most contentious topics  
in radiation safety. Tritium is a radioactive form of hydrogen, but  
is considered less of a cancer risk than substances such as radon  
that emit very large and damaging particles into cells when the  
elements decay.

However, some experts worry that tritium, because it is similar to  
hydrogen, binds readily with water and organic matter and therefore  
easily becomes embedded in living tissues, from which it can harm  
nearby cells.

In an interview, Dr. Fairlie said Ontario, with its large number of  
Candu stations, has some of the highest background levels of tritium  
in the world, and his recommendation about pregnant women living near  
nuclear plants was issued as a precaution, given the scientific  
uncertainty about its health effects.

He said the federal and Ontario government should establish an expert  
panel to determine whether the hazards of tritium need to be reviewed.

Canada considers drinking water containing up to 7,000 Becquerels per  
litre of tritium to be safe. A Becquerel represents one radioactive  
decay a second.

An Ontario government panel recommended in 1994 that the province set  
a drinking water limit of 100 Bq/L and then lower it to 20 Bq/L over  
a five-year period. But the advice, which would likely have led to  
occasional shutdowns of drinking water treatment facilities after  
radioactive releases at power plants, wasn't adopted. California  
recently set a goal of having drinking water contain 15 Bq/L or less,  
although this isn't a binding regulatory standard.

Small amounts of tritium are produced naturally in the environment,  
and pristine water typically contains about 2 Bq/L. However, water in  
both Lake Huron and Lake Ontario, where Candu reactors are sited,  
have about 7 Bq/L. The study said two-thirds of the radioactivity in  
the two lakes is from nuclear plant discharges.

According to the study, testing by the Ontario government found  
tritium in drinking water as high as 120 Bq/L on Lake Huron near one  
of the province's three nuclear plants.