Researchers Analyze Chromosomes for Radiation Security and Nuclear Emergencies – Well being and Way of life

To ensure the safety of occupationally exposed workers as well as potential victims in the event of a nuclear or radiological emergency, researchers from the Ministry of Science and Technology of the Philippine Nuclear Research Institute (DOST-PNRI) continue to examine blood samples for signs of radiation exposure beyond the legal limits.

Radiation exposure monitoring is becoming even more important with the increasing diversity of nuclear and radiation-related technologies in factories and businesses. In the Philippines, most of the workers who are regularly exposed to radiation are from industry and medicine.

In addition to local users of radioactive materials, an increasing number of Filipino Overseas Workers (OFW) trained in non-destructive testing are also using radiation in aircraft maintenance and other industries. The safety requirements for their further employment abroad also include an assessment of their radiation exposure.

To help our “Bagong Bayani” monitor their radiation doses, PNRI researchers use cytogenetic biodosimetry to analyze the chromosomes in their white blood cells to see if there are any aberrations that could indicate radiation damage.

Most chromosomes look like the letter “X”, which consists of two arms connected by a centromere. Dicentric chromosomes instead have two centromeres, which means that they are affected by ionizing radiation. From there, researchers can approximate whether a worker has exceeded their dose, which is proportional to the number of dicentric chromosomes.

As the regulator for nuclear and radioactive materials and facilities, PNRI also adopts international standards for radiation protection, including exposure limits for workers and the public. This is measured in Sieverts, the SI unit for the dose of ionizing radiation absorbed by the human body.

According to the Code of PNRI Regulations, radiation workers are only allowed to distribute up to 50 millisieverts per year or an average of 20 millisieverts per year of radiation over five years. In contrast, the general public can only be exposed to up to 1 millisievert per year.

While many of our medical and industrial professionals wear dosimeters to monitor their exposure, chromosome analysis provides a more direct estimate of the effects of radiation on a person’s body.

The dicentric chromosome test is the “gold standard” in biological dosimetry because it is specific for ionizing radiation, sensitive and cheap.

Cytogenetics can also be used for emergency preparedness and response, as researchers can assess the absorbed radiation doses from people involved in nuclear or radiological incidents.

After the 2011 Fukushima nuclear accident, PNRI has since worked hard to improve its cytogenetic skills. The researchers recently published their results on the established dicentric chromosome response curve of white blood cells versus various doses of gamma radiation, obtained by sampling a small population of healthy donors and counting their dicentrics after experimental radiation exposure. This dose-response curve is used to extrapolate the absorbed dose in individuals suspected of having been exposed to radiation.

In addition to monitoring radiation exposure, PNRI is also working with the Radiation Therapy Department of the Jose Reyes Memorial Medial Center to investigate the use of cytogenetics in determining radiation sensitivity of cancer patients to improve cancer patient radiation therapy outcomes.

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