Indian scientists have devised a way of repurposing nuclear waste for medical purposes. The Bhabha Atomic Research Center (BARC) in the Trombay suburb of Mumbai has put to use the radioactive isotope caesium-137 – created as a by-product of the nuclear energy process – to replace cobalt-60 in a life saving procedure used to prevent adverse reactions to blood transfusions.
The procedure irradiates transfused blood in attempts to remove the chance of the host developing transfusion-associated graft-versus-host disease (TA-GvHD). The disease is caused by the transfer of viable T-lymphocytes (T-cells), involved in immune response. If the cells are not rejected by the transfusion recipient they can cause an immune reaction that damages the recipient’s lymphoid tissue.
The disease is more likely to occur in those with immunodeficiency syndromes, though no association with HIV/AIDS has been found. Occurrences have been documented in HLA-matched transfusions, transfusions from blood relatives, stem cell transplantation, bone marrow transplantation, intrauterine and exchange transfusions, patients with congenital immunodeficiency syndromes and in those with lymphomas.
The frequency of occurrence is entirely limited to the immunocompromised. Even then it is an infrequent phenomenon. Despite being rare, the disease has a high mortality rate and so is still a considerable concern.
There is currently no treatment for TA-GvHD, though it is entirely preventable. Current methods involve exposing the blood to gamma radiation prior to the transfusion. This method kills the T-cells present in the sample and has been shown to be effective as a prevention strategy.
Previously, cobalt-60 was used as the source of the gamma radiation. Though this suffers the downside of an inconvenient half life of 5.3 years. This means that its use requires the frequent production, transport and re-installation of cobalt-60 samples. Caesium-137 has a much longer half life of 30.2 years, though in the past was only available in powdered form and presented a dispersal hazard.
BARC researchers have solved this issue by developing a solid form of caesium-137, mixed with molten glass in a process called vitrification. The caesium itself being sourced from reprocessed fuel from nuclear power plants. This comes with the added benefit of reducing the radioactivity of the waste, as well as heat production. This not only produces a product with medical applications, but ensures nuclear waste products are slightly less environmentally damaging.
The molten glass infused with caesium-137 is then placed into metal “pencils” and sealed before transport. This is now being done at an industrial level in the Waste Immobilization Plant at BARC’s Trombay home. The application for the usage of caesium-137 extends beyond medication. As a more stable isotope lasting for a longer time than cobalt-60 it could be utilised in sterilisation of equipment and food, with the added advantage of utilising a waste product of India’s nuclear power plants.