8 Monitoring Vivo Cytogenetic Damage In

Chromosomal alterations have been used as an important biological endpoint to study the mutagenic effects of ionizing radiation and chemicals. Some basic principles in radiobiology were based on chromosome aberration data obtained in plant cells and Drosophila (Lea, 1946). Structural and numerical chromosomal aberrations are encountered often in human newborns (0.6%) and in spontaneous abortions (30 to 40%). In addition, many tumors are associated with chromosomal aberrations that may be involved in the initiation or promotion stages of carcinogenesis. These facts emphasize the importance of studying chromosome aberrations per se as a relevant biological endpoint to assess the risks involved in exposure to mutagenic carcinogens. The origin and significance of chromosomal alterations have been discussed earlier (Natarajan, 1984). The techniques to detect chromosomal changes have been improved constantly to increase the ease and accuracy of recognition of aberrations, and in some cases automation has become available. In this review, the authors summarize some of the recent significant advances in this field. Biological endpoints to be discussed include chromosomal aberrations, micronuclei, sister chromatid exchanges, and aneuploidy. In in vivo studies, only