Correlation between cytogenetic biomarkers obtained from DC and CBMN assays caused by low dose radon exposure in smokers.

Purpose: Radon is of health concern because they can cause lung cancer when inhaled over many years. Cytogenetic biomarkers proved to be excellent methods to detect and estimate radiation induced DNA damage. Two well established cytogenetic assays are available to detect the DNA damage caused by ionizing radiation namely Dicentric (DC) assay and Cytokinesis-Blocked Micro Nucleus (CBMN) assay. Chromosomal aberrations such as dicentric and acentric fragments can be analyzed in DC assay. Micronuclei and Nucleoplasmic bridges can be analyzed in CBMN assay. The present study focuses on correlation between the aberrations observed in DC and CBMN assay caused by low doses of radon in smokers. Material and methods: Blood samples were collected, after prior consent, from smokers as well as healthy non-smoking individuals and exposed in vitro to radon ranging between 0-5.2 mGy using a simple, portable irradiation assembly designed and tested at authors' laboratory.

Results

A significant increase in frequencies of dicentrics and excess acentric fragments were observed with increasing dose. Interestingly in CBMN assay also, the frequencies of micronuclei and nucleoplasmic bridges were increased with dose. There was a significant correlation between nucleoplasmic bridges and dicentrics for both smokers and non-smokers. Significant correlation between acentric fragments and micronucleus was observed only for non-smokers.

Conclusions

By considering the correlation between the two cytogenetic assays, the CBMN assay can be used as an alternative to DC assay for non-smokers. In case of smokers, nucleoplasmic bridges can be used to measure the radiation exposure. This study is first of its kind to correlate the cytogenetic biomarkers obtained from DC and CBMN assay for smokers with very low doses of radon.