Elsevier

The Lancet Oncology

Volume 16, Issue 13, October 2015, Pages 1316-1323
The Lancet Oncology

Articles
Risk of death among children of atomic bomb survivors after 62 years of follow-up: a cohort study

https://doi.org/10.1016/S1470-2045(15)00209-0Get rights and content

Summary

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.

Findings

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.

Interpretation

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.

Funding

Japanese Ministry of Health, Labour and Welfare, US Department of Energy.

Introduction

Children of radiation-exposed parents are predicted to have higher rates of mendelian and multifactorial genetic diseases. However, no clear epidemiological effects have been shown in the first filial (F1) generation of people after parental radiation exposure.1, 2, 3 Concerns of possible deleterious effects among children conceived after parental exposure to the atomic bombs in Hiroshima and Nagasaki led to the creation of the atomic bomb survivors F1 mortality cohort. Previous reports on this cohort have not noted increased cancer incidence or cancer mortality.4, 5, 6, 7, 8 Despite these findings, surveillance has continued as scientific interest and public attention have remained focused on the health effects of ionising radiation. Questions to be answered include the dangers of diagnostic radiography among children, the full effects of the Fukushima nuclear power plant disaster, and germline mutations that could be passed to following generations.

With nearly 63 years of follow-up, the F1 mortality cohort is the longest running study of children born to parents exposed to ionising radiation and has an instrumental role in establishing long-term health effects of parental radiation exposure. This report updates the radiation risks of death caused by cancer and non-cancer diseases among the children of the survivors of the atomic bombings up to 2010 and includes 10 additional years of follow-up since the last report.8

Section snippets

Study design and participants

This study uses a prospective cohort design. Children conceived after the atomic bombings and born in Hiroshima and Nagasaki were identified via city birth records or by active recruitment at city offices where pregnant women could apply for supplemental rice allowances. Parents were interviewed or matched to a master list of survivors based on the 1950 Japanese National Census to determine parental exposure status. All singleton children with one or both parents within 2 km of the hypocentres

Results

The F1 mortality cohort consists of 76 814 people. Cohort members were excluded if they were not Japanese nationals (n=763), their residence could not be determined (n=663), had an unknown date of death (n=2), they explicitly withdrew from the study (n=8), or if they did not survive at least 1 day (n=51). Thus, 75 327 participants were analysed. Slightly more than half of the children were male and most were born in Hiroshima. Half of the cohort was born before 1955. Mothers tended to be

Discussion

We did not detect any associations between parental radiation exposure and mortality among children after the atomic bombings in Hiroshima and Nagasaki. Non-cancer-related mortality occurred more often in the early follow-up period whereas deaths caused by cancer tended to occur more often in the later period. This cohort included a high proportion of all children born to proximally exposed atomic bomb survivors who resided in Hiroshima or Nagasaki at the time of their child's birth. Our

References (29)

  • MP Little et al.

    Evidence relevant to untargeted and transgenerational effects in the offspring of irradiated parents

    Mutat Res

    (2013)
  • YE Dubrova et al.

    Minisatellite germline mutation rate in the Techa River population

    Mutat Res

    (2006)
  • Sources and effects of ionizing radiation

    (2001)
  • The 2007 recommendations of the International Commission on Radiological Protection. ICRP publication 103

    Ann ICRP

    (2007)
  • Health risks from exposure to low levels of ionizing radiation: BEIR VII Phase 2

    (2006)
  • JV Neel et al.

    Mortality in the children of atomic bomb survivors and controls

    Genetics

    (1974)
  • Y Yoshimoto

    Cancer risk among children of atomic bomb survivors. A review of RERF epidemiologic studies. Radiation Effects Research Foundation

    JAMA

    (1990)
  • Y Yoshimoto et al.

    Mortality among the offspring (F1) of atomic bomb survivors, 1946-85

    J Radiat Res

    (1991)
  • S Izumi et al.

    Cancer incidence in children and young adults did not increase relative to parental exposure to atomic bombs

    Br J Cancer

    (2003)
  • S Izumi et al.

    Radiation-related mortality among offspring of atomic bomb survivors: a half-century of follow-up

    Int J Cancer

    (2003)
  • GW Beebe et al.

    Studies of the mortality of A-bomb survivors. I. Plan of study and mortality in the medical subsample (selection 1), 1950-1958

    Radiat Res

    (1962)
  • K Ozasa et al.

    Invited commentary: missing doses in the Life Span Study of Japanese atomic bomb survivors

    Am J Epidemiol

    (2013)
  • DA Pierce et al.

    Allowing for random errors in radiation dose estimates for the atomic bomb survivor data

    Radiat Res

    (1990)
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