Asian Pacifc Journal of Cancer Prevention, Vol 12, 2010 35 Evaluation of Genetic Alterations in an Area of Naturally High Level Background Radiation in India Asian Pacifc J Cancer Prev, 12, 35-41 Introduction Natural radiation is a major component of radiation exposure for the general population. In our natural environment, we are chronically exposed to low doses of ionizing radiation. In some situations, this environmental exposure can reach significant doses, such as in the case of some inhabited areas where the soil displays abnormally high amounts of radionuclides. There are many high level natural radiation areas (HLNRAs) throughout the world like those in Brazil, China, India and Iran. The people who live in the HLNRAs of the world are of considerable interest because they have been exposed to abnormally high radiation levels over many generations (Mortazavi et al., 2005). From the earlier reports of background radiation levels in India, it is well known that the Agastheeswaram taluk 1 Human Molecular Genetics Laboratory, School of Life Sciences, Bharathiar University, Tamil Nadu, India, 2 PSG Medical College, Coimbatore, 3 Department of Biotechnology, Kongunadu college, Coimbatore, India, 4 Solid State and Radiation Physics Laboratory, Department of Physics, Bharathiar University, Tamil Nadu, India, 5 Universita degli studi di Padova, Department of Chemical Science, Padova, Italy, 6 Center for Frontier Life Sciences, Nagasaki University, Japan, 7 Department of Physics, Karunya University, Coimbatore, 8 Department of Physics, Kalasalingam University, Sivakasi, India. *For correspondence: drk_sasi@yahoo.com Abstract Evaluation of genetic alterations in inhabitants of an area of Tamil Nadu, India, chronically exposed to high background radiation (HBRA), was the major purpose of the present study. A total of 216 samples (exposed inhabitants, 108; control subjects, 108) were selected based on the confrmation of radiation dose level using thermoluminescence dosimetry (TLD). After signing a consent form, volunteers provided blood samples (5 ml each) to establish cell cultures at 52 h. One hundred complete metaphase cells from each subject were evaluated for karyotyping. The frequencies of chromosomal alterations (CA) were found to be higher in the exposed groups and the aberrations predominately observed were of chromatid-type. Smoking was found to have considerable effect on the frequency of CA in exposed subjects. With the comet assay for DNA damage, a signifcant increase in comet tail frequency was also observed in exposed subjects compared to controls. At present there are no radioepidemiological data regarding the cytogenetic studies in these areas. Furthermore, the Kudankulam nuclear power plant nuclear power plant is being constructed in the same area. The study gives potentially important information on the general health effects due to radiation exposure and increases people’s understanding of the hazardous nature of chronic low level natural radiation exposure. However, we may conclude that the HBRA by itself does not pose any signifcant risk of genetic damage as measured by conventional cytogenetic analysis. Keywords: High background radiation area - DNA damage - nuclear power plant - cytogenetics RESEARCH COMMUNICATION Evaluation of Genetic Alterations in Inhabitants of a Naturally High Level Background Radiation and Kudankulam Nuclear Power Project Site in India Vellingiri Balachandar 1 , Ramesh Kumar Mithun Kumar 2 , Varsha Prakash 1 , Subramaniam Mohana Devi 1 , Balasubramanian Lakshman Kumar 1,3 , Pappusamy Manikantan 1 , Keshavarao Sasikala 1* , Jeyapandian Malathi 4,5 , Muruganandam Brahmanandhan 4,6 , D Khanna 3,7 , S Selvasekarapandian 3,8 (sub-district) and its adjoining taluk, namely Thovalai of the Kanyakumari district, is one of the high background radiation areas (HBRA) and known for its high thoron concentrations (Khanna et al., 2005; Malathi et al., 2005; 2008). In addition, a 6000 MWe nuclear power plant is now under construction at Kudankulam, situated in the Radhapuram Taluk of Tirunelveli District (southern part of Indian sub-continent) by the Indian Government with the help of Russian Federation. The activity concentrations of 232 Th, 238 U and 40 K in Radhapuram taluk have been evaluated from the soil samples collected at various locations. The activity concentration of 232 Th in soil has been found to be 6 times higher than the world average (30 Bq.kg–1) and the activity concentration of 40 K has been found to be 0.7 times less than the world average (400 Bq.kg–1). In sand sample activity concentration of 232 Th is found to be 41 times higher than the world average