Professor Lynn Fraser told the 21st annual conference of the European Society of Human Reproduction and Embryology today (Wednesday), that her previous research had shown that certain chemicals known to mimic the female sex hormone, oestrogen, could individually affect the correct functioning of mouse sperm, but now her new research showed that when the chemicals were combined they had an even stronger effect. In addition, when she tested one chemical, genistein (found in soya and legumes), on human sperm, she found that the human sperm were much more sensitive to it than mouse sperm. Even tiny doses could cause human sperm to "burn out" and lose fertility.
Prof Fraser, who is Professor of Reproductive Biology at King's College London, said: "Given that these environmental oestrogenic xenobiotics [chemicals] are effective at very low concentrations, with combinations of compounds being even more potent, these results could have important negative implications for human fertility for two reasons. Firstly, humans are likely to be exposed to more than one such compound at any given time and, secondly, our results show that human sperm are even more sensitive to these compounds than mouse sperm."
Prof Fraser and her team tested combinations of three chemicals: genistein, 8-prenylnaringenin which is found in hops, and nonylphenol which is found in industrial products such as paints, herbicides and pesticides, cleaning products and in the production of pulp paper and textiles. They investigated the effect the chemicals had on capacitation, the stage when a sperm acquires the ability to fertilise an egg.
"We found that combinations of small quantities of these three xenobiotics stimulated sperm far more than when used individually," she said. In particular, the chemicals stimulated the sper
Source:European Society for Human Reproduction and Embryology