The purpose of this study was to estimate predictive markers of intrinsic radiosensitivity in individuals who were exposed to occupational or environmental radiation. Throughout this process, the actual biohazard risks and base-line chromosome damage were evaluated in human population. Further studies were carried out to provide evidence for the existence of individual variations in age-dependent responses through micronuclei (MN) assay.Spontaneous frequencies not only vary greatly between individuals, but also working or living areas. It was shown that the increased level of spontaneous cell with MN was observed with increasing age. The relationship between radiosensitivity and the increased spontaneous level of MN may be in an inverse proportion. Ionizing radiation may be targeted mutagenic effects at the usual exposures of background levels that populations were exposed. Age and gender are the most important demographic variables in determining the MN index with frequencies in females, which were greater than those in males. The main life-style factors influencing the MN index in subjects were correlated significantly and positively with smoke. The results showed that an indicator of the genetic damaged rate in MN index in human populations significantly correlated with age, sex and life-style factors. So far, it is evident that with regard to the application of MN assay all future studies have to take into account the influence of age, gender, and life-style.In Conclusion, using micronuclei assay technique a large population can be easily monitored. This study illustrated that the MN assay may provide a high potential to ensure appropriate quality control and standard documentation protocol that can be used to monitor a large population exposed to radiation epidemiologically.
Adolescent ; Adult ; Age Factors ; Aged ; Background Radiation/*adverse effects ; Chromosomes, Human/radiation effects ; Environmental Exposure/*adverse effects ; Female ; Humans ; Korea ; Life Style ; Lymphocytes/*radiation effects/ultrastructure ; Male ; Micronuclei, Chromosome-Defective/*radiation effects ; *Micronucleus Tests ; Middle Aged ; Occupational Exposure/*adverse effects ; Radiation Tolerance/*physiology ; Sex Factors

Ionizing radiation including I131 might produce chromosomal translocation, causing hematologic malignancy. The incidence of leukemia following radioactive iodine treatment for thyroid cancer has been reported to be approximately 0.1 to 2.0% in Western countries, whereas fewer cases have been reported in Korea. We hereby report four cases of secondary hematologic malignancy, who received iodine therapy for thyroid cancer after thyroidectomy: two cases of acute lymphoblastic leukemia with t(9;22)(q34;q11.2), a case of MDS with 5q deletion, and a case of MDS with normal karyotype. Three cases of hematologic malignancy have developed after cumulative dosage of less than 800 mCi. The treatment intervals in two cases were less than 12 months, and the other two cases had I131 therapy only once. Assessment of causality using the Naranjo probability scale for adverse drug reactions showed that a 'possible' relationship existed between the use of I131 and secondary hematologic malignancy in all of the four cases in this report.
Adult ; Chromosomes, Human, Pair 22 ; Chromosomes, Human, Pair 5 ; Chromosomes, Human, Pair 9 ; Female ; Gene Deletion ; Hematologic Neoplasms/*diagnosis/genetics ; Humans ; Iodine Radioisotopes/*adverse effects/therapeutic use ; Leukemia, Radiation-Induced/*diagnosis/etiology ; Middle Aged ; Myelodysplastic Syndromes/diagnosis/genetics ; Neoplasms, Second Primary/*diagnosis/genetics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma/diagnosis/genetics ; Thyroid Neoplasms/*radiotherapy ; Thyroidectomy ; Translocation, Genetic