Comments on “No Lengthening of Life Span in Mice Continuously Exposed to Gamma Rays at Very Low Dose Rates” by S. Tanakaet al.(Radiat. Res.160, 376–379, 2003)

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Download Full-text

Dose Responses for Chromosome Aberrations Produced in Noncycling Primary Human Fibroblasts by Alpha Particles, and by Gamma Rays Delivered at Sublimiting Low Dose Rates

Radiation Research ◽

10.1667/0033-7587(2002)158[0043:drfcap]2.0.co;2 ◽

2002 ◽

Vol 158 (1) ◽

pp. 43-53 ◽

Cited By ~ 34

Author(s):

Michael N. Cornforth ◽

Susan M. Bailey ◽

Edwin H. Goodwin

Keyword(s):

Gamma Rays ◽

Chromosome Aberrations ◽

Low Dose ◽

Human Fibroblasts ◽

Alpha Particles ◽

Dose Rates ◽

Dose Responses

Download Full-text

Cytogenetic Damage Induced in Human Lymphocytes by Low Doses of60co Gamma Rays Delivered at High and Low Dose Rates

Acta Radiologica Oncology ◽

10.3109/02841868609136393 ◽

1986 ◽

Vol 25 (2) ◽

pp. 143-146 ◽

Cited By ~ 4

Author(s):

L. Fabry

Keyword(s):

Gamma Rays ◽

Low Dose ◽

Human Lymphocytes ◽

Low Doses ◽

Cytogenetic Damage ◽

Dose Rates

Download Full-text

Influence of Various Commercial Packaging Conditions on Survival of Escherichia coli O157:H7 to Irradiation by Electron Beam Versus Gamma Rays

Journal of Food Protection ◽

10.4315/0362-028x-62.1.10 ◽

1999 ◽

Vol 62 (1) ◽

pp. 10-15 ◽

Cited By ~ 51

Author(s):

VERÓNICA LÓPEZ-GONZÁLEZ ◽

PETER S. MURANO ◽

ROBERT E. BRENNAN ◽

ELSA A. MURANO

Keyword(s):

Escherichia Coli ◽

Electron Beam ◽

Gamma Rays ◽

Low Dose ◽

Microbial Population ◽

Escherichia Coli O157 ◽

Dose Rates ◽

Polyethylene Bags ◽

Effect Of Oxygen ◽

Permeability Rate

Irradiation of ground beef patties inoculated with the organism Escherichia coli O157:H7 was performed either by gamma rays from a cobalt 60 source or by electron beam generated by a linear accelerator. Patties were packaged in one of the following materials: nylon/polyethylene bags, Saran/polyester/polyethylene bags (PM2), or Saran overwrap with a Styrofoam tray inside. Bags were sealed in air or under vacuum and were irradiated at either 5 or −15°C. Average D10 values (dose required to inactivate 90% of a microbial population) ranged from 0.27 to 0.63 kGy, depending on the conditions. Overall, higher D10 values (P < 0.0001) were obtained upon irradiation at −15°C as compared with 5°C. Cells inoculated in samples packaged in PM2 had the highest D10 values, but only if irradiated by electron beam at −15°C (P < 0.001). Since PM2 had the lowest oxygen permeability rate and since the temperature was too low for radicals to migrate easily, these conditions may have minimized the effect of oxygen- and water-derived radicals on microbial survival. Irradiation by gamma rays resulted in higher D10 values (P < 0.047) than irradiation by electron beam, with the highest values being observed at −15°C. Differences may be attributed to dose rate (1.0 kGy/h for gamma, 17 kGy/min for electron beam) since it is possible that, at low dose rates, microbial enzymes may have more time to repair damage to the cell due to irradiation, resulting in higher D10 values.

Download Full-text