The Application of Comet and Micronucleus Assay for the Assessment of Individual Radiation Risk

Abstract

One of the central goals of biological dosimetry must be the assessment of individual radiosensitivity. Physical dosimetry is only able to give the information on the energy deposited in the human body. This is not sufficient in radiation protection, because the response of the body to radiation dose is much more important than dose itself. This response strongly depends on the individual radiosensitivity, which is not determinable by physical means Several biological indicator systems have been introduced meanwhile from which answers are hoped to be obtained. One of the major factors affecting individual radiosensitivity is the repair capacity of a person. The comet assay offers the possibility to monitor repair at the level of single cells. Thus, one obtains not only information on the average repair capacity but also on the range. Individual cells are irradiated in vitro and checked for DNA damage either immediately or after various times at 37 °C. The speed of damage removal and the amount of residual damage after a fixed time gives the desired information on the repair capacity. Pronounced differences among people have been found up to now, whereas samples taken from one person at different times show remarkably similar results. Since the introduction of the CB technique, micronuclei in lymphocytes are successfully used as a biological dosemeter after radiation exposure. Their analysis is much faster and easier than that one of dicentrics. The comparatively poor sensitivity in the low dose range can be overcome by isolating sensitive subpopulations of lymphocytes. In addition or alternatively, centromere identification within the micronuclei improves sensitivity of the assay. Very promising is the fact that automatic scoring of micronuclei is feasible and can be done routinely meanwhile.