Re: low level radiation effects

[Hank Roberts <hank@spamcop.net>]

I'm an interested reader; my dad did some early radiation biology research

on cell division -- light microscopy, looking at dividing cells over many

hours and keeping track of how they did when irradiated in various ways,

compared to controls from the garden.



I did one of my grade school science fair project by taking ordinary beans

to the local university's Van de Graff (electron beam) irradiation

facility, and having three samples irradiated at different levels, then

planting those and a control sample and measuring germination percentage,

time, and the size of the resulting seedlings.



No one I talked to -- not my father, with his experience in cytology, nor

the people at the university radiation lab -- was surprised that the

sample that was given low level radiation treatment looked better than the

controls -- more beans germinated, the shoots were on average taller with

bigger leaves earlier.  The medium intensity exposed plants were pretty

sad looking, and the high intensity exposed plants were few and far

between.



This was somewhere around 1959-1960.  No one, as I recall, suggested that

the radiation was doing anything in particular to the bean seeds -- dry

beans don't have a lot going on.  The speculation was that the low level

irradiation had knocked back the activity or success of the many bacteria

and fungi normally on and in the seeds.



I'd think any research looking into low level environmental radiation has

to be done with appropriate controls for the same reason -- take for the

exposure group the population that was irradiated by building with

contaminated rebar, in the living environment --the occupants present

while the environment was irradiated there; and for the comparison group,

irradiate a comparable living environment (along with their clothing and

foodstuff) for 2x for 12 hours with that group of occupants absent.  n



You need to look for the possibility that it's an environmental effect,

with the irradiation damaging the fast-dividing bacteria and fungi living

in the irradiated area so they do less harm to the people who live there.



Low level effects require either a huge N, or a great many measurements

taken over a long period of time, to get statistically significant

differences.



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