May as well post the article from previous link:

One of the worst byproducts of the atomic age
continues to show up in our teeth
MICHAEL DOWNEY
December 2, 1999

Toronto -- Strontium 90, the atomic-age horror of 40 years ago, is still with us -- deep within us. An element unknown to science until spawned by the first nuclear-weapons tests, Sr90 continues to be found in our very bones. Suddenly, children born 30 years after the last bomb exploded in the atmosphere are exhibiting unexpectedly significant amounts of Sr90.

Back in the 1950s, its presence in baby teeth was blamed for a surge in cancer among children, and public pressure led in 1963 to then U.S. president John F. Kennedy's decision to sign a nuclear test-ban treaty with the Soviet Union.

A byproduct of nuclear fission, Sr90 is a marker for radiation poisoning that damages DNA much more quickly, even before birth, than any environmental pollutants. Nuclear particles remain lodged -- often for life -- in human tissues, where they continue to give off radiation and result in cancer, birth defects and premature aging.

And to make matters worse, industrial chemicals in water or milk are doubly carcinogenic when in contact with Sr90.

Where all this new radiation comes from is a matter of debate.

For scientists like Dr. Jay Gould of the U.S. Radiation and Public Health Project, there are only two possibilities: accidents of the kind that damaged the nuclear power plant at Three Mile Island, Pa., in 1976, or radiation escaping from properly functioning facilities. Evidence, he says, comes from data released by the U.S. Department of Energy that shows a decline in the amount of Sr90 in adult bone and diet from 1964 to 1970 -- after above-ground bomb testing ended.

"The amount declined on average by 16 per cent each year," he says. "If this decline had continued, there would be only trace amounts of Sr90 in baby teeth today." Amounts should be barely measurable -- about .3 or .4 picocuries per gram of calcium, he says. This would be in keeping with the half-life of radioactive material. In the case of Sr90 it is 29 years, or the time it takes for half its radioactive matter to decay.

Instead, scientists found levels as high as 2 to 17 picocuries per gram of calcium, he says.

"This could not possibly be attributed to past bomb tests."

Dr. Gould, who served on the U.S. Environmental Protection Agency Science Advisory Board under President Jimmy Carter, also says anyone living within 150 kilometres of a nuclear facility has a greater risk of breast or prostate cancer. Recent studies suggest people stand to suffer 20 times more cell damage than was suspected at the time safety standards were set in the mid-1950s.

On the other hand, Dr. Murray Stewart, president and CEO of the Canadian Nuclear Association, says any increase in radiation is much more likely to be caused by previous above-ground testing. Radiation released from Canadian plants is "infinitesimally small," he says. "Studies have never shown any link between commercial reactors or commercial uranium to any incidence of cancer."

Two nuclear workers at a research plant in Chalk River, Ont., would disagree -- if they could. In 1981, they received full pensions as a result of getting cancer caused by radiation exposure. One pension went immediately to the widow of one of the workers and other claims soon followed.

Atomic Energy Commission (AECL) spokesman Hal Tracy says the nuclear industry in Canada now accepts the theory that there is no safe threshold limit for radiation exposure. Any dose, no matter how small, has the potential to cause harm and eventually there will be evidence of this harm, he says.

Tell that to the nuclear neighbourhood. Fish near the Pickering nuclear plant on Lake Ontario, and at the Bruce site on Lake Huron, have been found to be radioactive -- likely caused by the tonnes of mildly radioactive water routinely flushed into the lakes. And Ontario Hydro admits that some apples and onions grown near its powerplants are up to 100 times more radioactive than "normal," yet are still well within official "safe" limits.

In all, about 80 radioactive byproducts in some way manage to reach the air, soil, water, where they remain active and eventually enter our food.

Radiation also works its questionable magic on some elements found naturally in the environment. After a brush with radiation, about 300 previously innocent chemicals take on radioactive forms that before 1943 were found only in trace quantities here and there in isolated places. Sr90 itself did not exist in nature prior to the nuclear age. While some radiation existed, only radionuclides or radiated atoms can be created via atomic fission.

If all this is considered normal, then so is the problem of nuclear waste. When removed from the reactor core, it is about a million times more radioactive than when it was loaded. A freshly spent fuel bundle is reckoned to be so deadly that a person standing only a metre away would die of radiation poisoning within an hour.

There is no antidote to its toxicity and never will be. Each year, we produce 100 tonnes of nuclear waste per plant and manage only to isolate the stuff some place where it can be left to decay for 240,000 years, the half-life of plutonium.

The technique could hardly be described as safe. After all, the Egyptian pharaohs were supposed to be entombed forever, too. According to a 1991 AECL workshop, the industry could never simply put waste out of mind. "We cannot think we have done aperfect job, seal it, and forget about it . . . Future generations must be able to repair the facility."

None of this sounds very encouraging to Dr. Gould. His study group, also known as the Tooth Fairy project, has been measuring the presence of Sr90 in the baby teeth of American children born some 20 years ago, and early results show levels to be "100 times higher than we expected."

Some 1,500 teeth have been collected from parents who had kept the teeth as keepsakes. The collection includes 550 teeth from children born between 1979 and 1982. These teeth had the same level of Sr90 as that found in a similar study conducted in 1953, says Dr. Gould.

Colleague Dr. Janet Sherman, a Virginia internal-medicine specialist and toxicologist, says the results are frightening.

"We're finding that Sr90 levels in baby teeth of children born since 1990 are reaching levels that were in existence during the above-ground testing years, which is very scary," she says.

The finding is not entirely unprecedented. Tests on baby teeth in Germany after fallout from the nuclear accident at Chernobyl, Ukraine, in 1986 showed a tenfold increase in Sr-90. Fallout also reached North America, says Dr. Gould. Radiation carried in wind patterns and released in rainfall caused profound effects upon birth weights and auto-immune functions, he says.

For Dr. Gould, who next wants to test the teeth of Canadian children, Chernobyl and other similar accidents all point to responsibility for the continued presence of Sr90.

For the moment, his Tooth Fairy project offers no solutions, only deeply disturbing questions. Long after it should have diminished in potency, Sr90 promises to be a terrifying threat well into the next century.

Michael Downey is a Toronto writer specializing in science.

HOW STRONTIUM 90 STRIKES

Strontium 90 and other radioactive material gets into vegetation, including grass and vegetables. If cows eat tainted grass, their milk picks up radioactive material which stays active for years.

"The mother consumes milk, vegetables and cheese and the Sr90 goes up the food chain," says Dr. Janet Sherman of the Tooth Fairy Project. "These kids are getting it in utero [in the womb] . . . So if you're talking about healthy [nuclear] workers, they may not drink much milk. And they're already developed."

Children are vulnerable in a way that adults are not. Radioactive particles can settle in any part of our bodies; but children knit Sr90 into growing bones and teeth when their bodies mistake it for calcium. Dr. Sherman says children who exhibit high levels of Sr90 show a higher-than-normal rate of a rare form of bone cancer. Other effects can be delayed for years or generations.

Radiation takes the form of high-energy rays and particles. Beta rays for example, are fast electrons that lose energy as they pass through our cells. The transferred energy disrupts chemical bonds; the strands of our DNA break. Improper rejoining of these DNA ends causes key sections of DNA to be lost. While some cells die, others -- forever changed -- become altered blueprints for mutated or cancerous cells.