title: Life-span carcinogenicity studies on Sprague-Dawley rats exposed to γ-radiation: design of the project and report on the tumor occurrence after post-natal radiation exposure (6 weeks of age) delivered in a single acute exposure.
abstract: BACKGROUND
  Experimental long-term carcinogenicity bioassays conducted on rats and mice proved that ionizing radiation can induce a variety of tumor types. However few studies have been conducted on rats.
  
  
  METHODS
  This report deals with the effects of γ-radiation in groups of 416-1,051 6-weeks old Sprague-Dawley rats exposed to 0, 0.1, 1, or 3 Gy of γ-radiation delivered in a single acute exposure. The experiment lasted for the animals' lifespan and all were necropsied and underwent full histopathological evaluation.
  
  
  RESULTS
  The results confirm the dose-related carcinogenic effects of γ-radiation for several organs and tissues. Moreover they indicate that exposure to 0.1 Gy induces a statistically significant increased incidence in Zymbal gland carcinomas and pancreas islet cell carcinomas in females.
  
  
  CONCLUSIONS
  Our data show that exposure to γ-radiation induces carcinogenic effects at all tested doses.
authors.affiliation: Cesare Maltoni Cancer Research Center, Ramazzini Institute, Bologna, Italy.
authors.forename: Morando
authors.initials: M
authors.lastname: Soffritti
authors.forename: Eva
authors.initials: E
authors.lastname: Tibaldi
authors.forename: Luciano
authors.initials: L
authors.lastname: Bua
authors.forename: Michela
authors.initials: M
authors.lastname: Padovani
authors.forename: Laura
authors.initials: L
authors.lastname: Falcioni
authors.forename: Michelina
authors.initials: M
authors.lastname: Lauriola
authors.forename: Marco
authors.initials: M
authors.lastname: Manservigi
authors.forename: Fabiana
authors.initials: F
authors.lastname: Manservisi
authors.forename: Fiorella
authors.initials: F
authors.lastname: Belpoggi
mesh_terms: D000818:Animals; D001344:Autopsy; D015197:Carcinogenicity Tests; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays / Q000009:adverse effects*; D008297:Male; D009369:Neoplasms / Q000145:classification / Q000453:epidemiology* / Q000209:etiology*; D016016:Proportional Hazards Models; D011829:Radiation Dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D012107:Research Design
keywords: carcinogenicity; life-span bioassay; low-dose; rat; γ-radiation