Life span and low dose rate gamma exposure

[niton@mchsi.com]

Interesting recent article with fairly decent sample size. 



Radiation Research: Vol. 160, No. 3, pp. 376–379.



No Lengthening of Life Span in Mice Continuously Exposed to Gamma Rays at Very 

Low Dose Rates

S. Tanaka,a, 1 I. B. Tanaka, III,a S. Sasagawa,a K. Ichinohe,a T. Takabatake,a 

S. Matsushita,b T. Matsumoto,a H. Otsu,a and F. Satoa



aDepartment of Radiobiology, Institute for Environmental Sciences. 1-7, 

Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan



bLaboratory of Animal Development and Research Group, National Institute of 

Radiological Sciences. 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, 

Japan

 



ABSTRACT



Tanaka, S., Tanaka, I. B. III., Sasagawa, S., Ichinohe, K., Takabatake, T., 

Matsushita, S., Matsumoto, T., Otsu, H. and Sato, F. No Lengthening of Life 

Span in Mice Continuously Exposed to Gamma Rays at Very Low Dose Rates. Radiat. 

Res. 160, 376–379 (2003).



Late effects of continuous exposure to ionizing radiation are potential hazards 

to workers in radiation facilities as well as to the general public. Recently, 

low-dose-rate and low-dose effects have become a serious concern. Using a total 

of 4000 mice, we studied the late biological effects of chronic exposure to low-

dose-rate radiation as assayed by life span. Two thousand male and 2000 female 

8-week-old specific-pathogen-free (SPF) B6C3F1 mice were randomly divided into 

four groups (one nonirradiated control and three irradiated). Irradiation was 

carried out for approximately 400 days using 137Cs  rays at dose rates of 21 

mGy day–1, 1.1 mGy day–1 and 0.05 mGy day–1 with total doses equivalent to 8000 

mGy, 400 mGy and 20 mGy, respectively. All mice were kept under SPF conditions 

until they died spontaneously. Statistical analyses showed that the life spans 

of mice of both sexes irradiated with 21 mGy day–1 (P < 0.0001) and of females 

irradiated with 1.1 mGy day–1 (P < 0.05) were significantly shorter than those 

of the control group. Our results show no evidence of lengthened life span in 

mice continuously exposed to very low dose rates of  rays.

> There are two things here.  NBC did an investigative

> report and shipped harmless DU.  However, it some

> group X announces the latest report on the "dangerous"

> health effects of DU, NBC is obligated to report about

> the "dangerous" DU.  Otherwise, they are censoring the

> story, and group X will sue them.  

> 

> In the best of all worlds, another group Y should

> counter the "dangerous" DU story as being B.S.  But

> that seldom happens as they have to move onto the next

> exciting story involving Brittney Spears. 

> 

> 

> --- "Borisky, Michael (Civ, ARL/CoS)"

> <mborisky@arl.army.mil> wrote:

> > Radsafers,

> >  

> > Did anyone notice on the evening news last night

> > that when (I think) NBC

> > was describing how NBC was able to secretly ship 15

> > pounds of DU from

> > Indonesia to Los Angles without it being detected at

> > our borders, NBC

> > called it "harmless"?  They then said DU has roughly

> > the same radiation

> > signature as bomb material that is shielded to avoid

> > detection, so



> > secretly shipping the DU served as a test run for

> > the ability to detect

> > something not so harmless.  I wonder if the next

> > time that NBC airs a

> > story about the purported health hazards of DU on

> > past and present

> > battlefields, they will remember that when it served

> > their purpose, they

> > described DU as "harmless"  

> >  

> > Mike Borisky

> > Army Research Lab 

> > 

> 

> 

> =====

> "May we never confuse honest dissent with disloyal subversion." 

> 

> Dwight D. Eisenhower  

> 

> -- John

> John Jacobus, MS

> Certified Health Physicist

> e-mail:  crispy_bird@yahoo.com

> 

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