title: Effect of carbon ions on life span shortening and tumorigenesis in mice.
abstract: One of the important concerns for astronauts in space is cancer risk associated with cosmic radiation, including heavy particle ions. But little information on cancer risk is available. We investigated the effect of carbon ions on life span shortening and tumor induction in B6C3F1 mice. The mice were exposed weekly to 0.4 and 2.0 Gy whole-body carbon-ion- or X-ray-irradiation for 4 consecutive weeks. The spectrum of induced tumors varied depending on the dose. The cause of death was thymic lymphomas and liver tumors at high and low dose, respectively. The life span shortening by X-rays was proportional to dose, while carbon ions produced a convex upward relationship. The relative biological effectiveness for the 50% life span shortening was about 1.4. The large effect of carbon ions encourages the study on tumor induction at low doses in the space.
authors.affiliation: Low Dose Radiation Effect Project, National Institute of Radiological Sciences.
authors.forename: Shizuko
authors.initials: S
authors.lastname: Kakinuma
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kubo
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Amasaki
authors.forename: Kumie
authors.initials: K
authors.lastname: Nohima
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Imaoka
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nishimura
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Shimada
mesh_terms: D000818:Animals; D002244:Carbon; D004307:Dose-Response Relationship, Radiation; D020450:Heavy Ions; D008136:Longevity / Q000528:radiation effects; D051379:Mice; D008815:Mice, Inbred Strains; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000401:mortality; D012062:Relative Biological Effectiveness; D014965:X-Rays
chemical_list: D002244:Carbon