Normal value for the direct micronucleus test on peripheral blood mononuclear cells from healthy donors

OBJECTIVE: To obtain the normal value of micronuclei in peripheral blood mononuclear cells. STUDY DESIGN: We screened 300 blood samples for micronucleated cells. Samples from donors who smoked, were ill or lived in a polluted area were excluded. From each sample, 500 swollen mononuclear leukocytes were screened with a light microscope, using 400 x magnification. A frequency distribution of micronucleated cell number was made, and the mean of micronucleated cell number was calculated. Further, the data were tested for the type of probability distribution using the test of goodness of fit, and the parameters were estimated. RESULTS: Of the 300 samples, 203 were excluded and 97 analyzed. In the 97 samples, the mean of micronucleated cells (from 500 cells screened) was 0.59; the data followed a Poisson distribution. The 95% confidence limits were .45 and .76. CONCLUSION: The normal value in unexposed individuals is .59 micronucleated cells per 500 cells.