DECREASED SENSITIVITY TO THE CYTOGENETIC EFFECTS OF BLEOMYCIN IN INDIVIDUALS OCCUPATIONALLY EXPOSED TO IONIZING-RADIATION

In the present work, 12 individuals occupationally exposed to ionizing radiation and 11 unexposed ones were studied to determine the cytogen etic effect of a challenge dose of bleomycin on their phytohemagglutin in stimulated lymphocytes. After bleomycin treatment, the frequencies of chromatid breaks and gaps were significantly lower in the exposed p opulation (p < 0.025 for both types of chromatid alterations). These r esults could indicate that occupational exposure to ionizing radiation can induce an adaptive response that can be detected by a subsequent treatment with bleomycin.