Effects of Radioactive MnO Particle Inhalation on Mouse Lungs: A Comparison between C57BL and BALB/c.

The effects of residual radiation from atomic bombs have been considered to be minimal because of its low levels of external radioactivity. However, studies involving atomic bomb survivors exposed to only residual radiation in Hiroshima and Nagasaki have indicated possible adverse health effects. Thus, we investigated the biological effects of radioactive dust of manganese dioxide 56 (MnO), a major radioisotope formed in soil by neutron beams from a bomb.

Effects of Internal Exposure of Radioactive MnO Particles on the Lung in C57BL Mice.

The investigation of the radiation effects of the atomic bombing in Hiroshima and Nagasaki has revealed concerns about the impact of the residual radioactive dust produced in the soil. Manganese-56 is one of the major radioisotopes produced by neutrons from the bomb; hence, we previously examined the biological effects of manganese dioxide-56 (MnO) in Wistar rats, in which significant changes were found in the lung. In the present study, ten-week-old male C57BL mice were exposed to three doses of radioactive MnO, stable MnO particles, or external γ-rays (2 Gy) to further examine the effects of MnO in a different species.

Hepatic Gene Expression Changes in Rats Internally Exposed to Radioactive MnO Particles at Low Doses.

We have studied the biological effects of the internal exposure to radioactive manganese-56 dioxide (MnO), the major radioisotope dust found in soil after atomic bomb explosions. Our previous study of blood chemistry indicated a possible adverse effect of MnO on the liver. In the present study, we further examined the effects on the liver by determining changes in hepatic gene expressions.

Biological impacts on the lungs in rats internally exposed to radioactive MnO particle.

To understand the radiation effects of the atomic bombing of Hiroshima and Nagasaki among the survivors, radiation from neutron-induced radioisotopes in soil should be considered in addition to the initial radiation directly received from the bombs. Mn, which emits both β particles and γ-rays, is one of the dominant radioisotopes created in soil by neutrons from the bomb. Thus we investigated the biological effects of internal exposure to MnO particle in the lung of male Wistar rats comparing to the effects of external Co-γ irradiation.

Low-Dose Radiation Exposure with MnO Powder Changes Gene Expressions in the Testes and the Prostate in Rats.

To investigate the biological effects of internal exposure of radioactive MnO powder, the major radioisotope dust in the soil after atomic bomb explosions, on male reproductive function, the gene expression of the testes and the prostate was examined. Ten-week-old male Wistar rats were exposed to three doses of radioactive MnO powder (41-100 mGy in whole body doses), stable MnO powder, or external Co γ-rays (2 Gy). Animals were necropsied on Days 3 and 61 postexposure.