Cytogenetic biomonitoring of Brazilian dentists occupationally exposed to low doses of X-radiation

Abstract

Exposure to X-rays (ionizing radiation) may cause chromosomal aberrations (CA) in somatic or germinative cells in exposed individuals, and may lead to manifestations of diseases such as cancer. This study was carried out to assess the CA frequency in lymphocytes obtained by means of temporary culture of peripheral blood from dentists in Londrina, Paraná, Brazil, who have worked for more than ten years with X-rays. The results obtained from the experimental group were compared with a matched negative control group, which had never been exposed to X-rays. All individuals, dentists and controls, answered a personal questionnaire, from which a profile of each group was obtained. Slides, prepared after the cultures, were stained with Giemsa, and 100 to 200 metaphase cells were analyzed per individual. CA frequencies and types were registered and statistical tests were not necessary to evaluate the obtained data. The analysis of mitotic index (MI) did not indicate significant differences (p < 0.05) between the group of individuals exposed to X-rays and the control group. The analyzed confounding factors did not influence the results of MI and CA frequencies. UNITERMS: Chromosome aberrations; Occupational exposure; Mitotic index; Dentist's practice patterns; X-rays. RESUMO:A exposição à radiação ionizante pode causar aberrações cromossômicas (AC) em células somáticas ou germinativas dos indivíduos expostos, podendo levar a manifestações de doenças como os cânceres. Este trabalho teve como objetivo avaliar a freqüência de AC em linfócitos obtidos através de cultura temporária do sangue periférico de dentistas de Londrina (Paraná -Brasil), com mais de dez anos de trabalho com raios X. Os resultados obtidos do grupo experimental foram comparados com um grupo controle negativo pareado, que nunca se expôs ocupacionalmente aos raios X. Todos os indivíduos, dentistas e controles, responderam a um questionário pessoal, a partir do qual foi obtido um perfil de cada grupo. Após as culturas, as lâminas foram confeccionadas, coradas com solução de Giemsa e foram analisadas de 100 a 200 células metafásicas por indivíduo, anotando-se as freqüências e tipos de AC encontrados. Não foi necessária a realização de testes estatísticos para avaliação desses parâmetros. A análise dos índices mitóticos (IM) não indicou diferenças significantes (p < 0,05) entre os indivíduos dos grupos expostos e controle. Os fatores de variação analisados não influenciaram os resultados obtidos para o IM e freqüência de AC.

Cytogenetic analysis in lymphocytes from radiation workers exposed to low level of ionizing radiation in radiotherapy, CT-scan and angiocardiography units

“…Movafagh et al in their study on radiotherapy workers found that neither age, sex or duration of exposure were significant predictors of chromosomal aberrations [20]. Miyaji and Mara in their cytogenetic study of dentist occupationally exposed to low doses of X radiation found no association between the confounding factors age and sex and the frequency of chromosomal aberrations [21]. The reason for obtaining not so significant results could be due to small sample size and limited age range in our study.…”

“…A small number of breaks remain unrepaired and become visible in subsequent metaphase chromosomes. Several studies performed using cytogenetic analysis, report the presence of increased frequencies of chromosomal aberrations in peripheral blood lymphocytes of individuals accidentally, environmentally or occupationally exposed to cumulative low level of ionizing radiation [3][4][5]. However, the relationship between ionizing radiation exposure level and the elevation of the frequencies of different types of structural chromosomal aberrations is not yet completely clarified.…”

Radiation Risk Assessment in Professionals Working in Dental Radiology Area using Buccal Micronucleus Cytome Assay

“…29 Significant cytogenic changes were not observed in a study conducted on blood samples of dentists exposed to low doses of ionizing radiation. 30 In the present study too, the MN cells frequency in the risk group was not significantly different from the control group. Routine radiation protection measures are followed in the area where this study was carried out.…”

Occupational radiation procedures and doses in South Korean dentists

“…Cases of radiogenic dermatitis and malignancies of the hand have been reported, and a greater incidence of thyroid cancer and melanoma and greater mortality from cardiovascular diseases have been observed. In addition, cytogenetic analyses have been carrie out to observe the possible mutations in the somatic cells of dentists, but no significant differences in chromosomal aberrations were found.…”