Association between paraben exposure and menstrual cycle in female university students in Japan.

Parabens have been known to have estrogenic activity in many in vivo and in vitro studies and biomonitoring data indicated ubiquitous exposure in general populations. However, there are few human studies on reproductive effects of parabens. In this study, menstrual cycle length and its intra-individual variation were investigated by bleeding record over the period of 5 months and urinary concentrations of parabens were measured for 128 female Japanese university students. We found significantly negative relationships between menstrual cycle length and urinary estrogen-equivalent total paraben (odds=0.73, 95% CI 0.56-0.96) and butyl paraben concentrations (odds=0.83, 0.70-0.99), which indicated shortened cycle length in women with high urinary paraben concentrations. This study indicated that paraben exposure at not excessive levels is associated with menstrual cycle length or its variability among general female subjects. These results suggest a possibility that parabens exposure is one of the environmental causes of human reproductive problem.