Date:09/08/2007 URL: http://www.thehindu.com/thehindu/seta/2007/08/09/stories/2007080950151500.htm Sci Tech
Spin-offs from radiation studies
Hiroshima and Nagasaki became the targets of atomic bombings on 6th and 9th August 1945 respectively. On November 18, 1946, the U.S. President Harry Truman authorised the National Research Council to set up an organisation “to undertake a long range, continuing study of the biological and medical effects of atomic bomb on man.”
The Atomic Bomb Casualty Commission (ABCC), the organisation established for the purpose and its predecessor, Radiation Effects Research Foundation (RERF), carried out and is carrying out priceless research on biomedical effects of radiation from June 1947 to date.
Studies pioneered by RERF at Hiroshima are making their impact on epidemiology, molecular and cellular biology, genetics, immunology and a range of other health sciences. From the 280,000 survivors in the two cities, the RERF researchers established fixed cohorts or sub-cohorts to provide epidemiological and clinical data on the health status and mortality of survivors and their children.
RERF researchers found that grip strength is a simple but useful measure to predict subsequent health of Japanese adults. Dr Hideo Sasaki, an expert panel member of RERF and other researchers followed up for 25 years, the survival status of 5,000 Adult Health Study participants (ages ranged from 35 to 74 years) who underwent grip strength testing between 1970 and 1972.
Low mortality
Total disease mortality was low among those with high grip strength. From 2002, RERF is focussing on the study of life-style related diseases such as hypertension, diabetes mellitus, myocardial infarction, stroke etc., that are not observable at birth but start to appear after middle age. On February 28 this year, RERF stated thus: “when multi-factorial disease in children were combined, no evidence suggesting increased risk associated with parental radiation exposure was observed.” In males, the study revealed that the prevalence rate of multi-factorial diseases decreased when paternal dose increased. “… Careful interpretation of this finding is necessary” RERF cautioned (RERF, February 2007)
Cancer incidence
Since 1950, RERF followed up the mortality of about 120,000 members of the Life Span Study cohort and carried out the cancer incidence studies since 1958.
Radiation-associated cancer risk increased significantly for oral cavity, stomach, colon, liver, lung, skin, breast, ovary, bladder system and thyroid. Rectum, gall bladder, pancreas, prostate or kidney did not indicate statistically significant increase in cancer risk. For the first time, the researchers found that the risk of cancer of the oesophagus was significant and radiation exposure at ages less than 20 years might increase the risk of uterus cancer. (Radiation Research, Ju ly 2007).
Physicians appointed by the Atomic Bomb Casualty Commission, examined 76,626 infants conceived and born in Hiroshima and Nagasaki over a period of six years starting from 1948.
Preliminary study did not reveal any discernible birth defect with radiation exposure. Follow up study on mortality, serum proteins and chromosome abnormalities did not reveal any radiation effect.
RERF continues with the study of a group of 3,600 persons through their middle and old age. Atomic bombing exposed them to radiation as they were then in their mothers’ wombs. One of the inputs to prescribe radiological protection standards emerged from the unparalleled epidemiological study at Hiroshima. Radiation protection specialists review the results periodically. They confirmed the robustness of these standards.
K.S. PARTHASARATHY
FORMER SECRETARY, AERB
K
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