Int. J. Hyg. Environ.-Health 208 (2005) 179–191 Assessment of DNA damage in nuclear medicine personnel – comparative study with the alkaline comet assay and the chromosome aberration test Nevenka Kopjar à , Vera Garaj-Vrhovac Institute for Medical Research and Occupational Health, Ksaverska c. 2, HR-10000 Zagreb, Croatia Received 22 April 2004; received in revised form 20 December 2004; accepted 30 January 2005 Abstract Despite much research over the last few decades, there still remains considerable uncertainty as to the genetic impact of ionizing radiation on human populations, particularly at low levels. The aim of the present study was to provide data on the genetic hazards due to occupational exposure of low doses of ionizing radiation in nuclear medicine departments. The assessment of primary DNA damage in peripheral blood leukocytes of medical staff was performed using the alkaline comet assay and the data obtained were compared with the results of conventional cytogenetic biodosimetry using the chromosome aberration (CA) test. Altogether 120 subjects (60 exposed and 60 controls) participated in the study. Statistically significant increases in primary DNA damage and increased frequencies of CAs compared to controls were observed. Within the exposed population, significant inter-individual differences in DNA damage were found, indicating differences in genome sensitivity. Age and gender were not confounding factors, while smoking enhanced the levels of primary DNA damage only in control subjects, as revealed by both biomarkers studied. The present study suggests that genotoxic damage results from exposure to chronic low doses of ionizing radiation in nuclear medicine departments. Therefore, the exposed medical personnel should carefully comply with the radiation protection procedures and should minimize radiation exposure where possible to avoid potential genotoxic effects. The results obtained in this study point to the significance of biological indicators providing information on the actual risk to the radiation exposed individuals. According to our results, the alkaline comet assay and CA test are sensitive biomarkers that can be used as additional complements to physical dosimetry for assessing exposure to radiation in nuclear medicine personnel. r 2005 Elsevier GmbH. All rights reserved. Keywords: Nuclear medicine; Peripheral blood leukocytes; DNA damage; Alkaline comet assay; Lymphocytes; Chromosome aberration test Introduction Occupational exposure in nuclear medicine depart- ments is mainly related to low doses of particular ionizing emissions from radioactive isotopes such as 99 mTc, 131 I, 32 P, 67 Ga, 111 In, 201 Tl, 59 Fe, 57 Co, 51 Cr, 192 Ir (Hagelstro¨m et al., 1995; Fischer and Becker, 2002; Bozkurt et al., 2003). These radioisotopes have unstable nuclei, and dissipate excess energy by spontaneously emitting radiation in form of gamma and other rays. It should be noted that, once a radiopharmaceutical has been administered, the patient becomes a mobile source of radiation exposure to several critical groups of individuals including their families, other patients and ARTICLE IN PRESS www.elsevier.de/ijheh 1438-4639/$-see front matter r 2005 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijheh.2005.01.027 à Corresponding author. Tel.: +38514673188; fax: +38514673303. E-mail address: nkopjar@imi.hr (N. Kopjar).