Parabens generate reactive oxygen species in human spermatozoa

Parabens are used as antimicrobial preservative agent in many commercial products including cosmetics and pharmaceuticals. Weak oestrogenic and antiandrogenic activities have been attributed to parabens in invitro and invivo studies. In this study, human spermatozoa were exposed to different concentrations of an equimolar paraben mixture containing methyl, ethyl, propyl and butylparaben as well as to methylparaben alone at a concentration that is typical of commercially available vaginal lubricants. The induction of oxidative stress and DNA damage was then assessed at different time points. Our results demonstrate that the paraben mixture was capable of stimulating the generation of mitochondrial and cytosolic reactive oxygen species (ROS), inhibiting sperm motility and viability in a dose-dependent manner. The ability of individual parabens to activate ROS generation and induce oxidative DNA damage was related to alkyl chain length. At the concentration used clinically, methylparaben inhibited sperm motility after both 2 and 5h exposure (p<0.05) and affected cell viability (p<0.01) while augmenting ROS production and oxidative DNA damage. However, DNA fragmentation was not evident following methylparaben exposure. Based on these results, we conclude that, at the concentrations used in commercially available formulations, parabens may impair sperm motility, enhance the generation of mitochondrial ROS and stimulate the formation of oxidative DNA adducts. Taken together, these data underline the potential cytotoxic and genotoxic impact of such compounds in a clinical setting.