Re: how many sensitive cells?

[JMUCKERHEIDE@delphi.com]

A very good source Wade,

I don't have the Bond et al (1991, NAS) source at hand. If you do can you
share it? 

As Dave notes, education in biology has been extremely limited in hp education 
and training: it is also "overlooked" :-) as Wade notes about the data by UBIN 
(since most university and other gov't training programs are funded by those
who are committed to UBIN and their funding agencies). 

The "biology rationale" summarized by Dave and others is part of the problem.
This is the "disinformation" that rationalize the basis for the LNT and
extreme rad protection (as evidenced by the concerns about opening I-131 in
hoods and being exposed to a patient - radiophobia for which we can not blame
the "ignorant media", and this isn't just "we have to because our ignorant
regulators make us", this is going out of our way to add cost and fear to rad
exposures, even though 1.3 mr/hr is 100 times background!, it's nothing
compared to the dose to the "wearer" :-)  which has been shown to have no
adverse effects. 

Getting a Tl-201 cardiac stress test, with 20 mr/hr external contact dose,
setting off nuclear plant monitors up to 3 weeks later as recently discussed
here, comes with a brochure that says this is done "a million times a year
with no adverse health effects". Studies following patients confirm it. But we 
foolishly buy and use monitors set at such levels, actively question trivial
exposures, and, *by our own actions*, create adverse reactions in the public,
not even constrained by the foolishness of gov't regulators both from the lack 
of scientific/technical training and from efforts to justify make-work for
bureaucratic advantages - and we blame the media?? 

Yet of the hundreds on this list and elsewhere that do know better, and talk
about "educating the kids" and "advocating to provide understanding with the
media", we produce no substantive response to this sad state of affairs. And
while the HPS Presidents, who have reviewed the evidence, especially as
provided by Wade Patterson, and published at his own initiative and expense in 
the HPJ, take a policy position that states that there can be no risk under 5
rem/year, 10 rem lifetime (though that one's conservatively inconsistent with
the scientific evidence). 

Is anybody listening? Is there ANY science anymore?

Thanks Wade, (and a few other 'personal notes' :-)

Regards, Jim Muckerheide
jmuckerheide@delphi.com
Radiation, Science, and Health, Inc.

> Lester Slaback, Dave Sherer and others:
> 
> There many papers in the peer-reviewed literature that report cellular
> removal and repair of radiation damage. Up to now such data has been
> "overlooked" by UBIN.
> Here's an example of what I mean.
> 
> Azzam, E. I.; de Toledo, S. M.; Raaphorst, G. P.; Mitchel, R. E. J.
> Low-Dose Ionizing Radiation Decreases the Frequency of Neoplastic
> Transformation to a Level below the Spontaneous Rate in C3H 10T1/2
> Cells. Rad. Res. 146:369-373; October 1996.
> 
> Abstract:
> We have previously shown that chronic exposure of plateau-phase C3H
> 10T1/2 cells to cobalt-60 gamma radiation at doses as low as 10 cGy
> protected the cells against neoplastic transformation by a subsequent
> large acute radiation exposure. We have also shown that this induced
> resistance to neoplastic transformation correlated with an increased
> ability to repair radiation-induced chromosome breaks. We now show that
> a single exposure of quiescent cells to doses as low as 0.1 cGy also
> reduces the risk of neoplastic transformation, from the spontaneous
> level to a rate three- to fourfold below that level. Higher doses, up to
> 10 cGy at the same dose rate (0.24 cGy/min), did not reduce the
> neoplastic transformation frequency further. This protective effect was
> seen only in irradiated cells that were allowed to incubate at 370C
> before release from contact inhibition. Cells released into low-density
> subcultures immediately after irradiation had unchanged neoplastic
> transformation frequencies. These results demonstrate that low or
> chronic exposure to radiation can induce processes which protect the
> cell against naturally occurring as well as radiation-induced
> alterations that lead to cell transformation. If similar processes are
> induced in human cells, the results also suggest that a single low dose,
> at background or occupational exposure levels, may in some circumstances
> reduce rather than increase cancer risk, a conclusion inconsistent with
> the linear no-threshold model of cancer risk from radiation.
> 
> Best wishes to all.
> 
> -- 
> Wade