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[cdn-nucl-l] FW: New AECB dose limits
I guess we'll all be very safe now.
> From: Brown, Morgan
> Sent: Thursday, 2000 March 16, 9:25 AM
> To: Lloyd, Marilyn; Shewchuk, Larry; Cuttler, Jerry; Franta, Jaroslav;
> Whitlock, Jeremy
> Subject: New AECB dose limits
> In today's Globe and Mail. Written up in a way to make blood boil ...
> Regulator wants tighter limits on public exposure to radiation
> Some say Canadian control board's standards
> should be stricter still
> MARTIN MITTELSTAEDT
> Environment Reporter
> Thursday, March 16, 2000
> The level of radiation exposure considered safe by Canada's nuclear
> regulator is about to drop dramatically.
> The standards proposed by the Atomic Energy Control Board are based on new
> evidence that shows exposure to low levels of radiation is far more
> dangerous than previously thought.
> They indicate a higher margin of safety is needed for those living near or
> working at nuclear reactors, uranium mines, cancer treatment centres and
> research facilities.
> The standards are based on a reappraisal of cancer risk by the
> International Commission on Radiation Protection, a non-governmental body
> that sets guidelines worldwide.
> Yet some critics say the new limits may not be tough enough to protect the
> public and some heavily exposed workers -- such as airline pilots and
> flight attendants -- from cancer and birth defects.
> "There are some serious questions about whether what they're allowing in
> terms of the public dose is appropriate," said Irene Kock, a spokeswoman
> for Nuclear Awareness Project, an antinuclear group. "Every single
> exposure increases the risk of cancer."
> The new research shows that the level of radiation exposure previously
> believed to cause 13 cases of fatal cancer for every one million workers
> actually leads to 40 cases. (That amount is equal to about 14 chest X-rays
> or 10 high-altitude round trips by plane to Europe.)
> The AECB plans to lower by 80 per cent the exposure considered safe for
> members of the public, and by 60 per cent for nuclear workers.
> Companies holding a licence to operate a nuclear facility or use
> radioactive material won't be allowed to expose workers or the public to
> radiation doses over the new limits.
> Higher exposures for workers are based on an assumption that they are
> accept some additional risk in return for a job, the AECB says.
> The new standards, based on cancer rates among Japanese atomic-bomb
> survivors, are so strict that many nuclear-medicine technologists and
> scientists will soon receive notices that they are exposed to enough
> radiation to be considered atomic-energy workers, just like uranium miners
> and nuclear-generating-station employees.
> About 6,000 workers a year exceed the proposed public-dose limit. Most are
> nuclear-plant workers, industrial radiographers, nuclear-medicine
> technologists and uranium miners.
> However, the new rules will not cover airline pilots and flight
> attendants, two groups that receive high radiation doses because aircraft
> fly at elevations that expose crews to more cosmic radiation from space
> than those at ground level.
> Patients receiving radiation therapy, who often are exposed to doses
> thousands of times higher than the new limits, will be exempt.
> NEW RADIATION DOSE LIMITS
> The dose limits in most countries are based on the recommendations of the
> International Commission on Radiation Protection. Using the most recent
> data on the effects of radiation, the ICRP recommended lowering the dose
> limits in 1991. These dose limits are only now being adopted.
> A millisievert (mSv) is the unit used to measure the dose equivalents from
> different types of radiation. Typically, Canadians receive between 2 and 3
> mSv a year from background radiation.
> Old dose New dose
> limit limit
> Average of
> Nuclear energy workers 50mSv/year 20 mSv/year*
> Pregnant nuclear energy workers 10 mSv/year 4 mSv/year
> Members of the public 5 mSv/year 1 mSv/year
> Note: If a single dose of 10 mSv is received by one million people, 500
> cases of fatal cancer are expected over their lifetimes.
> Typical radiation levels from different sources:
> 2.5 mSv Typical abdominal X-ray
> 2.5 mSv Annual dose from natural background in Canada
> 0.07 mSv Typical chest X-ray
> 0.1 mSv 9,700 kilometres of high-altitude flight
> 0.05 mSv...Living for a year near a nuclear generating station
> -*Actually 100 mSv/5years
> Source: AECB