Variation of Chromosome Aberration Rate in the Culture of Human Blood Lymphocytes with Time

Spontaneous chromosome aberration rate in human blood lymphocytes was studied using the data collected during 30 years. Seasonal variation was found. An absolute maximum of chromosome aberration rate was observed in winter and a local maximum, in summer. In spring and autumn, this value decreased. There was a statistically significant trend towards higher frequencies of aberrant metaphases during the period studied. A periodic pattern of changes in the chromosome aberration frequency was found. The data fitted a sinusoid with a period of 4.5 years.