title: Association between Local External Gamma Rays and Frequency of Cancer in Babol-Iran.
abstract: BACKGROUND
  The effect of natural background radiation on Cancer is still challenging. The investigation of association between external gamma rays and Cancer was the main goal of study. MATERIALS #ENTITYSTARTX00026;
  
  
  METHODS
  External Gamma rays were measured using a radiation survey meter in 184 urban and rural health centers to estimate the exposure to the population in residential areas of Babol. The dose distribution map was compared to the 5 years radiation induced cancer incidence data from cancer registry center in north part of Iran.
  
  
  RESULTS
  Results showed that although the external gamma ray level in Babol is nearly equal to the average natural background radiation in the world, there is a relatively weak inverse association between local external gamma ray and incidence of Cancer [Correlation coefficient = -0.43, (p<0.01)].
  
  
  CONCLUSIONS
  This finding might be due to the inhibition of cancer induction following exposure to the low doses of ionizing radiation and probably can be a confirmation of radiation hormesis. However, due to some uncertainties, the conclusion should be interpreted with caution. Further national and international studies are suggested.
authors.affiliation: Associate Professor of Medical Physics, Babol University of Medical Sciences, Babol-Iran.
authors.forename: Ali Shabestani
authors.initials: AS
authors.lastname: Monfared
authors.forename: Karimollah
authors.initials: K
authors.lastname: Hajian
authors.forename: Reza
authors.initials: R
authors.lastname: Hosseini
authors.forename: Akbar
authors.initials: A
authors.lastname: Nasir