Although individual men may suffer from low sperm counts or poor quality sperm making it difficult for them to father children, a more worrying statistic has recently come to light. This is the fact, discovered by scientists from the University of Copenhagen in 1990, that the sperm count in 20 of the world's countries has fallen by 50 percent over the last 50 years. In 1940, men produced around 113 million sperms per milliliter of seminal fluid; today only 66 million are produced, and by the year 2000, this figure is predicted to fall to 50 million. In theory, a lower sperm count does not equal infertility, but some scientists believe that the count will be down to zero in 70 or 80 years, unless something is done.

The reason for this catastrophic decline is still in debate, although it is considered by many authorities to be the result of artificial substances, such as plastics and pesticides leaching hormone-disrupting chemicals into the soil, water, and food chain. These chemicals can mimic the female hormone estrogen, disrupt the production of the male hormone testosterone, or disturb the functioning of the endocrine system, which regulates the production of the body's hormones. Evidence indicates that birds and animals are also suffering from hormonal disruption. The fear is that these chemicals may also be linked to breast, testicle, and prostate cancer, endometriosis, and general damage to the immune system.

Some countries have reacted by banning PVC and other plastics for food packaging, but the chemical industry as a whole is awaiting the results of more research before it takes any action. There seems to be little that an individual can do since these chemicals are now ubiquitous, although taking steps to strengthen the immune system may help.