Effects of dose rate and energy level on fission neutron (252Cf) tumorigenesis in B6C3F1 mice.
The effects of the dose rate and the energy of fission neutrons using an iron block on tumorigenesis in B6C3F1 mice were examined. Six-week-old female animals were divided into 4 groups and exposes to 252Cf neutron irradiation at dose rates of 0.05 cGy/min, with (Group 1) or without (Group 2) filtering through a 10 cm thick iron block, 0.8 cGy/min (Group 3) or 0 (Group 4 controls). Total neutron exposure was 50 cGy in each of groups 1-3 and total irradiation dose was 56, 75 and 75 cGy in Groups 1-3, respectively. Total tumor incidences or multiplicity were significantly higher in Group 3 than in Group 1. A similar tendency was observed as compared to Group 2, ovarian and Harderian gland tumors being mainly affected and adrenal tumors were significantly higher in Group 2 than in Group 1. The results indicated a clear increase in tumorigenesis with the higher dose rate and no filtering influence of iron was evident, despite the drop in neutron energy level.
Watanabe
H
H
Department of Cancer Research, Hiroshima University, Japan.
Okamoto
T
T
Yamada
K
K
Ando
Y
Y
Ito
A
A
Hoshi
M
M
Sawada
S
S
D000818:Animals; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D009678:Nuclear Energy; D009680:Nuclear Fission; D011829:Radiation Dosage