The single cell gel electrophoresis/comet assay: a potential tool for detecting radiation-induced DNA damage in humans.

This review evaluates the applicability of the single cell gel (SCG)/comet assay as a tool for the biomonitoring of individuals accidently, environmentally or occupationally exposed to ionizing radiation. This technique detects single-strand DNA breaks, alkali-labile damage, incomplete excision repair sites and DNA:DNA crosslinking at the level of the individual cell. The advantages of this technique include: (a) data are collected at the level of the individual cell, providing information on the intercellular distribution of damage and repair; (b) only small numbers of cells are required (i.e., only a few thousand); (c) virtually any eukaryotic cell population can be used; and (d) the assay is relatively sensitive (detection limit of 5 cGy gamma rays in human lymphocytes), simple and cost effective. What the assay lacks is specificity for radiation-induced DNA damage. However, the possibility of identifying types of DNA damage specific for ionizing radiation in selected subtypes of cells may be feasible. While additional research is required before the SCG assay can readily be applied as a standard biomonitoring tool for exposure to ionizing radiation, the data collected thus far support a conclusion that such research is clearly warranted.