Variability in chromosome aberrations, sister chromatid exchanges, and mitogen-induced blastogenesis in peripheral lymphocytes from control individuals.

Confidence in results from monitoring genetic end points in environmentally or occupationally exposed individuals can be improved with knowledge of the normal variability of changes in genetic end points in the general population. Confounding effects can be determined, and study interpretation can be improved by correlation of this variability with various lifestyle factors such as sex and age, smoking and drinking habits, viral infections, exposure to diagnostic X-rays, etc. Eight blood samples were taken from each of 24 male and 24 female volunteers over a period of 2 years. Questionnaires pertaining to lifestyle were completed at the time of each sampling. Whole blood was cultured and slides prepared for chromosome aberration (CA) or sister chromatid exchange (SCE) analysis. Separated mononuclear cells were cultured with a range of phytohemagglutinin concentrations, and the maximum level of mitogen-induced blastogenesis was determined by measurement of [3H]thymidine uptake. There was a significant effect of both year and season of sampling for all three end points. Because there was no consistent pattern in 2 successive years, effects were thought to be independent of season. No significant effects in any of the three end points were found with respect to sex or age nor any of the other lifestyle factors, although SCE frequency and mitogen-induced blastogenesis were nearly always higher in females than in males. These results point to the need for concurrent sampling of controls with exposed populations.