The effect of donor sex and age on the number of sister chromatid exchanges in human lymphocytes growing in vitro.

After analysing the distribution of the numbers of sister chromatid exchanges (SCE) in 200 cells from one individual, we found no evidence to reject the hypothesis of a normal distribution (P greater than 0.50). We then compared the mean numbers of SCE per cell in 18 individuals, three males and three females of each of three age groups (0-10, 30-40, and 60-70 years of age) by means of a one-way analysis of variance, and found that there was no significant difference among them at the level of 5%. When these data were analysed by means of a two-way analysis of variance to test separately the effect of sex and age, we found that the number of SCE per cell does not differ significantly between sexes, but differs with age (P Less Than 0.05). People in the age bracket 30-40 years have a higher number of SCE per cell. Age seems to affect both sexes equally.