The destruction of a household could leave a surviving child with injuries and no parents to care for them. Families had to find relatives, shelter, food and work while still grieving. Some survivors who appeared to have escaped serious injury developed symptoms of acute radiation sickness afterward.
Doctors in Hiroshima began noticing excess leukemia by the late 1940s. Longer follow-up in both cities identified elevated risks of several solid cancers that could persist throughout a survivor’s life. Risk varied with radiation dose and age at exposure. These studies describe patterns across groups of people, and an individual survivor’s diagnosis still has its own medical history.
Some hibakusha concealed their exposure because they feared losing a job or a marriage prospect. Survivors and families had to negotiate that stigma alongside treatment, bereavement, and the uncertainty of future illness.
- 1957
Medical care
Japan enacted a law providing medical care for qualifying atomic bomb survivors. Which kinds of exposure qualified became a question with practical consequences for access to care.
- 1968
Additional support
A special measures law expanded support. The 1957 and 1968 laws formed the basis for the later national survivors’ support system.
- 1994–1995
A consolidated support law
The Atomic Bomb Survivors’ Support Law was promulgated in 1994 and took effect in 1995, bringing the earlier measures together.
- Radiation Effects Research Foundation · Leukemia risks
- Radiation Effects Research Foundation · Solid cancer risks
- National Museum of Nuclear Science & History · Survivors and discrimination
- Prefectural University of Hiroshima repository · History of survivors’ support (PDF)
In 2021, the Hiroshima High Court ruled in favor of people seeking survivor health handbooks after exposure to black rain. Hiroshima later published guidance for people with circumstances similar to those of the plaintiffs.
City of Hiroshima · Guidance after the black rain ruling (Japanese)
What changed in the first days and weeks
The blast and heat could cause immediate injury, and high radiation doses could cause a separate illness over the following days and weeks. Radiation Effects Research Foundation records describe symptoms including hair loss, bleeding and a drop in blood cell counts. These effects help explain why early accounts of who appeared to be recovering could change so quickly.
Beginning in the postwar years, the Atomic Bomb Casualty Commission and Japanese research partners followed survivors in both cities. RERF succeeded the commission in 1975. Its long follow-up allows researchers to study differences by age and dose as well as changes over time. The studies quantify health risks across a population. Read the survivor accounts alongside them for the effects on work, family and everyday life.
When people died, and what the records can tell us
Hiroshima’s estimate is about 140,000 deaths by December 1945. Sudden death, later deaths from burns or injuries, and deaths after acute radiation illness are part of that early toll.
At high doses, radiation damaged the digestive system and bone marrow. Some people who survived the flash died days or weeks later. Fever, bleeding and infections could accompany failing blood-cell production. The medical chronology matters when reading a family account that describes someone returning home or appearing to recover before becoming ill.
Years later, leukemia was among the first detectable excesses. Studies identified increased risk for several solid cancers over much longer follow-up. Acute deaths and later deaths are documented using different methods. A city estimate, an individual death certificate, a memorial register and a research estimate each answers a different question.
- 1945
The emergency continued through the year
Injuries and acute radiation effects claimed lives after the first day. Families also faced homelessness, hunger and the loss of relatives and neighbors.
- Late 1940s onward
Doctors began seeing excess leukemia
Leukemia often emerged earlier than solid cancers. The two-city research followed survivors with different ages and estimated doses.
- 1950–2003
Long-term mortality follow-up
One research analysis estimated 527 additional solid-cancer deaths attributable to radiation in its defined two-city study population. The researchers used dose and follow-up data to estimate that excess.
- Later decades
Health, recognition and remembrance
Survivors continued seeking care, keeping records and sharing testimony. A memorial register preserves names according to its own criteria and cannot establish whether radiation caused each named person’s death.
How to read the 527 estimate
This is a modeled estimate drawn from both cities together over a specified period. It covers the cohort and cause of death studied. A comprehensive city-by-city tally of later deaths attributable to the bombing cannot be derived from this figure.
- RERF · Life Span Study mortality reports
- RERF · Explanation of late-effect mortality estimates (PDF)
- RERF · Early death estimates and radiation research FAQ
Follow a life across time
Read Sadako Sasaki’s story beside Setsuko Thurlow’s testimony. One family’s history reaches from a child’s exposure in 1945 to her death in 1955, while the other follows a survivor who spoke publicly for decades.