Re: Medical radiation workers see reduction in cancer risk

[garyi@trinityphysics.com]

I found it humerous that the pre-1950 elevated SMR is automatically assumed to be a 

radiation effect, while the post 1950 SMR<1 must be something else.



Also, if the post 1950 SMR<1 is valid, then what justification is there for any dose limit 

less than 5 cSv/yr, or ALARA?  If it ain't broke, then why are we trying to fix it?



Gary Isenhower



> Second, lower exposure levels were recorded after

> 1957, when the International Commission on

> Radiological Protection (ICRP) reduced the suggested

> dose limit to 0.05 Sv per year. In 1990, the

> commission revamped that policy to an occupational

> dose limit of an average of 0.02 Sv per year, over

> five years, and not to exceed an annual dose of 0.05

> Sv in a single year.

> 

> After 1950, the SMR for all types of cancer was less

> than 1. In addition to better dose parameters, a trend

> known as the "healthy-worker effect" may have

> contributed to the reduction as these professionals

> tend to lead healthier lifestyles and have better

> access to medical care, the authors stated.

> 

> "We found no clear evidence of cancer risk in any of

> the latest subcohorts of radiologists or

> technologists," the group concluded. "While safe

> radiation practices currently are an assumed part of

> medical radiation work ... it is important to continue

> follow-up."



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