Vaginal spermicides that contain Nonoxynol-9 are mutagenic in a bacterial back-mutation assay

4862

Cancer of the genital tract, particularly cervical cancer, is an important cause of cancer morbidity and mortality in women in the U.S.A. and elsewhere. Any persistent mutagenic or carcinogenic influence in the vagina is therefore of great potential significance in the causation of cancer. One such potential persistent influence is the presence of a mutagenic spermicidal gel. In the present study, the mutagenicity of three commonly used over-the-counter spermicidal gels containing Nonoxynol-9 as the active ingredient was examined in a bacterial assay, which was a modification of the Ames test. The results were compared with those in which a series of non-antibacterial and antibacterial products were examined. These products included a number of personal products that come into contact with mucous membranes as well as some caustic non-personal home products and a known mutagen, sodium azide. Whether these substances needed to be activated by liver enzymes in order to be mutagenic was also examined. The results showed that all three of the intravaginal spermicidal gels tested were as mutagenic or more mutagenic than the other products tested in each category. One caused frame shift type mutations and the other two point mutations. Although two of these products only became mutagenic following activation by liver extract, suggesting that in a clinical situation they might only be significant mutagens if systemically absorbed or ingested, the third was mutagenic without liver activation. It therefore might be expected to be directly mutagenic in the female, and indirectly in the male, genital tract. These results thus suggest that spermicidal gels, either acting alone or in concert with other potentially mutagenic and carcinogenic agents, may be a significant cause of cancer in women.