Pollutants mature sperm prematurely:

“Hormone-like chemicals in food and pesticides may stop adult sperm fertilizing eggs, suggests a new study. Some think that the findings may partly explain falling fertility rates.

Scientists have long speculated that chemicals similar to female hormone oestrogen in food and pesticides could cut sperm counts. Most of the debate has centred on whether such compounds stunt the growing testicles in babies.

Now comes some of the first evidence that environmental oestrogens can stop sperm from adult men fertilizing eggs. Researchers at Kings College London have found that mouse sperm bathed in low levels of the chemicals mature too fast.”