EUROPEAN RADIATION RESEARCH 2012

Lack of Oxidative Stress after Short-Term Exposure to Naturally Elevated Levels of Gamma Radiation in Ramsar

17 Oct 2012, 16:25

1m

Poster Hall (Vietri sul Mare)

poster preferred Oxidative Stress Poster Session 2

Speaker

Prof. SMJ Mortazavi (Shiraz University of Medical Sciences)

Description

Ramsar, a city in northern Iran, has areas with some of the highest recorded levels of natural radiation among inhabited areas measured on the earth. In some areas of Ramsar, residents receive an annual radiation dose from background radiation that is about 13 times higher than the 20 mSv/y that is considered as a dose limit for radiation workers. These residents have lived for many generations in these areas of high background radiation. In 2002 we reported on the induction of adaptive response in residents living in high background radiation areas of Ramsar. It is believed that the adaptive response involves the transcription of many genes and the activation of a wide variety of signaling pathways that trigger specific cell defense mechanisms. In this study, 53 Wistar rats were randomly divided into five groups of 10-12 animals. Animals in the 1st group were kept for 7 days in an outdoor area with normal background radiation while the 2nd, 3rd, 4th and 5th groups were kept in 4 different outdoor areas with naturally elevated levels of gamma radiation in Ramsar. A calibrated RDS-110 survey meter, mounted on a tripod approximately 1 meter above the ground, was used to measure exposure rate at each location. On days 7 and 9 blood sampling was performed to assess the serum levels of catalase (CAT) and malondialdehyde (MDA). On day 8, all animals were exposed to a lethal dose of 8 Gy gamma radiations emitted by a Theratron Phoenix (Theratronics, Canada) Cobalt-60 (55 cGy/min) at Radiotherapy Department of Razi Hospital in Rasht, Iran. Results obtained in this study indicate that high levels of natural radiation cannot induce oxidative stress. CAT and MDA levels in almost all groups were not significantly different (P=0.69 and P=0.05, respectively). After exposure to the lethal dose, CAT and MDA levels in all groups were not significantly different (P=0.054 and P=0.163, respectively). These findings indicate that short-term exposure to extremely high levels of natural radiation (up to 196 times higher than the normal background) does not induce oxidative stress.