Possible effects of hormonal contraceptives on human mitotic chromosomes.

Chromosome breakage, as an indicator of genetic damage, was assessed in peripheral blood lymphocytes of 44 women using different types of hormonal contraceptives (HC) for various periods of time, as well as on 44 matched controls. The selection of individuals for this study was preceded by the completion of a questionnaire to avoid, as far as possible, all cases subjected to known clastogenic agents. 48-h cultures were established by standard techniques and every sample from each "study" individual and her own matched "control" were simultaneously and similarly processed. The use of HC was found to be associated with a highly significant increase of chromosome aberrations in this in vivo study (p less than 0.001). The likelihood that the association found is a causal one is suggested and the theoretical clinical implications of these findings are discussed.