Chronic Low-Level Radiation & Chromosomal Changes

Chronic Low-Level Radiation Exposure Causes Chromosomal Aberrations

NEW YORK (Reuters Health) Dec 10 -

Chronic exposure of health workers to low-level ionizing radiation is associated with chromosomal aberrations and sister chromatid exchanges, according to a report in the December issue of Teratogenesis, Carcinogenesis, and Mutagenesis.

Chromosomal aberrations have been linked to carcinogenic genetic changes, the authors explain, so increased use of ionizing radiation that may cause genetic instability raises concerns about the health of those employed in operational radiology and nuclear medicine.

Dr. Elza Sakamoto-Hojo from Universidade de São Paulo in Brazil and colleagues compared chromosomal aberrations, sister chromatid exchanges, and micronuclei in lymphocytes from eight hospital workers chronically exposed to ionizing radiation (accumulated absorbed doses ranging from 9.5 to 209.4 mSv) with those in eight age-, sex-, and smoking habit-matched individuals not exposed to ionizing radiation.

Radiation workers had significantly more chromosomal aberrations (3.2 per 100 cells) than did control workers (2.4 per 100 cells) (p = 0.018), the authors report. Exposed individuals also had significantly more sister chromatid exchanges per cell (6.2) compared with unexposed individuals (5.8) (p = 0.025), the report indicates. MN per cell were higher in the exposed group (3.0 per cell) than in the unexposed group (2.6 per cell), the researchers note, but the difference was not statistically significant.

"The present study showed that workers professionally exposed to a low dose of gamma- and/or X-rays presented increased frequencies of chromosome damage in comparison to their matched controls, although the cumulative absorbed doses calculated by their personal physical dosimetry were within the limit established by the International Committee for Radiological Protection (ICRP)," the authors conclude.

"The best method (among the three methods described in the article) for biomonitoring is chromosomal aberration assay," Dr. Sakamoto-Hojo told Reuters Health. "Some other new methods involving molecular analysis can also be applied — for example, analysis of gene expression in large scale by cDNA microarrays." "We recommend the routine use of chromosomal aberration assay, at least once a year," Dr. Sakamoto-Hojo said. Dr. Sakamoto-Hojo also emphasized the importance of limiting exposure.

"The radiation workers should not work for [a] long time in the same function," Dr. Sakamoto-Hojo said. "The individual biomonitoring (physical and biological dosimetry) should be applied, and new rules of radioprotection must be introduced on the basis of genetic studies."

Teratogenesis Carcinog Mutagen 2001;21:431-439.

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