New Health Studies on A-bomb Survivors
By Dr KS ParthasarathyOn August 6, 2010, Hiroshima observed the 65 anniversary of the atom bombing. The anniversary of Nagasaki bombing was on August 9. For the first time, United States sent an envoy to Hiroshima.
The US ambassador to Japan, Mr John Roos, laid a wreath ‘to express respect for all of the victims of World Ward II’. Britain and France, its World War II allies sent their first diplomats to the ceremony, indicating support for the goal of nuclear disarmament. Mr Ban Ki-moon, the United Nations Secretary General is the first UN Chief to attend the function. Everyone wants to draw attention to the urgent need to achieve global nuclear disarmament.
In the hurry and excitement of global politics we may forget the priceless research on biomedical effects of radiation carried out by the Atomic Bomb Casualty Commission and its successor Radiation Effects Research Foundation (RERF) which was set up in 1975.
From the 280,000 survivors in the two cities, the RERF scientists established fixed cohorts or cohorts to provide epidemiological and clinical data on the health status and mortality of survivors and their children. The latest issue of RERF update, a publication from RERF, noted that RERF and ABCC scientists have been evaluating, documenting and publishing for the past 63 years, the long-term health effects associated with the ionising radiations emitted by the A-bombs in Hiroshima and Nagasaki.
"Much of the research of ABCC, and now RERF, has focused upon characterisation of the effects of the A-bomb radiation exposure on the immunological parameters in the survivors. Those studies are being conducted in an aging population in one of the longest-living and most homogeneous population in the world." (RERF update, 2010).
The US National Institute of Allergy and Infectious Diseases (NIAID) is funding the project. RERF researchers will be able to define the effects of ionising radiation on aging of the human immune system and elucidate the underlying mechanism.
The project is possible because they can use the large, unique data base and bio-samples from the 63-year follow up of A-bomb survivors. Co-investigators from five US and Japanese institutions will provide their expertise and methodologies for the success of the project.
The main focus of the project is immunosenescence, the gradual deterioration of the immune system with aging. The process involves many vital activities. The host’s ability to respond to infections may degrade; the development and retention of long term immune memory including the one generated by vaccination may diminish; the immune cell turnover may alter and an imbalance between the innate and adaptive immunity may potentially cause enhanced and persistent inflammatory responses.
When successfully concluded the studies may lay a foundation to explain some of the long term health effects observed in A-bomb survivors.
There is clear evidence for excess leukaemia and solid cancers among the exposed population. These observations helped the International Commission on Radiological Protection to recommend dose limits to workers and members of the public.
Recently researchers noted an increase is non cancer-diseases among the survivors. They can explain this only if their understanding of the defects in the individuals’ immunological system over time and with prior radiation exposure improves. They hope that such studies will provide a solid, scientifically grounded basis for risk assessment, regardless of the disease outcome of interest (RERF Update, 2010).
"It will open opportunities for prophylaxis, prevention and treatment of the resulting disorders", the researchers concluded. The latest RERF update summarised thirteen areas of research. RERF and its collaborating subcontractors will conduct four projects for elucidating the effects of ionizing radiation and aging on blood-derived stem cells, dendritic cells and their precursors (these are crucial in triggering immune response against infections) and on vaccination responses. The plan to develop an integrated scoring system for human immune competence as it relates to aging and ionising radiation.
The Departments of Clinical Studies in Hiroshima and Nagasaki have been carrying out Adult Health Study (AHS) for over 50 years. Summarising the work of these departments, Fuliwara and Akahoshi clarified that the objective of AHS is to determine radiation risks for diseases that cannot be documented adequately by the larger mortality study called Life Span Study (LSS) (RERF Update, 2010).
These studies include the effects of radiation on the risk of non fatal heart disease or stroke, high blood pressure, various benign tumours and other adverse health effects.
About 20,000 subjects in the AHS group have provided biological samples once every two years from 1958. The repeated samples proved invaluable as they are seldom available in any other project anywhere in the world.
RERF is carrying out a comprehensive study (F1 Clinical Study) on nearly 12,000 children of A-bomb survivors. It evaluates the possible association between radiation exposures of their parents and the frequency of diseases such as heart disease, stroke, hypertension and diabetes. Now their average age is 50; they have developed little disease thus far and there is scope for long term study.
From 1978, AHS group included 2000 additional high dose groups and nearly 1,000 (all available) persons who were exposed to A-bomb radiation while they were in their mother’s womb.
The relationships between exposure to radiation and non cancer -diseases were not expected. Recently, researchers discovered that radiation is associated with premature menopause. This may cause earlier onset of increase in cholesterol levels and cardiovascular disease.
RERF researchers are studying liver stiffness, chronic kidney disease and cardiovascular disease and their possible relationship with radiation exposure.
The clinical evaluation of nearly 12,000 children of A-bomb survivors provided no evidence of an increased prevalence of multi-factorial diseases in relation to their parental exposure.
RERF scientists noted that the prevalence of cataract increased with radiation dose with a dose-effect threshold that was much lower than previously believed.
RERF is continuing with intensive and extensive studies on human diseases’ with unparalleled resources at its command. Spin offs from these may help fight gruesome diseases. This may be the notable contribution from the dastardly event which occurred over six decades ago. PTI
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