title: Risk of death among children of atomic bomb survivors after 62 years of follow-up: a cohort study.
abstract: BACKGROUND
  No clear epidemiological hereditary effects of radiation exposure in human beings have been reported. However, no previous studies have investigated mortality into middle age in a population whose parents were exposed to substantial amounts of radiation before conception. We assessed mortality in children of the atomic bomb survivors after 62 years of follow-up.
  
  
  METHODS
  In this prospective cohort study, we assessed 75 327 singleton children of atomic bomb survivors in Hiroshima and Nagasaki and unexposed controls, born between 1946 and 1984, and followed up to Dec 31, 2009. Parental gonadal doses of radiation from the atomic bombings were the primary exposures. The primary endpoint was death due to cancer or non-cancer disease, based on death certificates.
  
  
  RESULTS
  Median follow-up was 54·3 years (IQR 45·4-59·3). 5183 participants died from disease. The mean age of the 68 689 surviving children at the end of follow-up was 53·1 years (SD 7·9) with 15 623 (23%) older than age 60 years. For parents who were exposed to a non-zero gonadal dose of radiation, the mean dose was 264 mGy (SD 463). We detected no association between maternal gonadal radiation exposure and risk of death caused by cancer (hazard ratio [HR] for 1 Gy change in exposure 0·891 [95% CI 0·693-1·145]; p=0·36) or risk of death caused by non-cancer diseases (0·973 [0·849-1·115]; p=0·69). Likewise, paternal exposure had no effect on deaths caused by cancer (0·815 [0·614-1·083]; p=0·14) or deaths caused by non-cancer disease (1·103 [0·979-1·241]; p=0·12). Age or time between parental exposure and delivery had no effect on risk of death.
  
  
  CONCLUSIONS
  Late effects of ionising radiation exposure include increased mortality risks, and models of the transgenerational effects of radiation exposure predict more genetic disease in the children of people exposed to radiation. However, children of people exposed to the atomic bombs in Hiroshima and Nagasaki had no indications of deleterious health effects after 62 years. Epidemiological studies complemented by sensitive molecular techniques are needed to understand the overall effects of preconception exposure to ionising radiation on human beings.
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan. Electronic address: egrant@rerf.or.jp.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Grant
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Kyoji
authors.initials: K
authors.lastname: Furukawa
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Ritsu
authors.initials: R
authors.lastname: Sakata
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Sugiyama
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sadakane
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Ikuno
authors.initials: I
authors.lastname: Takahashi
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Utada
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: The Radiation Effects Research Foundation, Minamiku, Hiroshima, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ozasa
mesh_terms: D000293:Adolescent; D000328:Adult; D032721:Adult Children; D000367:Age Factors; D016022:Case-Control Studies; D002423:Cause of Death; D002648:Child; D005260:Female; D040941:Heredity; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis / Q000235:genetics / Q000401:mortality*; D009689:Nuclear Warfare; D054043:Nuclear Weapons; D018812:Paternal Exposure / Q000009:adverse effects*; D011446:Prospective Studies; D011829:Radiation Dosage; D018570:Risk Assessment; D012307:Risk Factors; D017741:Survivors; D013997:Time Factors; D055815:Young Adult