The quality of Israeli sperm has declined alarmingly in the last decade, according to recent research conducted at Jerusalem's Hadassah University Hospital, Mount Scopus.

The cause for the decline is not known, but it's believed by some researchers to be connected to the exposure of children and pregnant women to hormones and other contaminants in food and water.

Conducted by Dr. Ronit Haimov-Kokhman, the study showed a 40-percent decline in the concentration of sperm cells among the country's sperm donors from 2004 to 2008, compared to those of donors from 1995 to 1999. Hadassah's sperm bank is now turning away two-thirds of potential donors because of low-quality sperm, as opposed to one-third in the past.

Haimov-Kokhman's research is to be presented today at a conference of the Israeli Society of Fertility Investigation in Tel Aviv.

Kokhman said the study was carried out to test the theory of the director of Hadassah Hospital's sperm bank, Ruth Har-Nir, that sperm quality was in decline.

The research confirmed that in 10 years, the average concentration of sperm among donors declined from 106 million cells per cubic centimeter to 67 million per cubic centimeter. The rate of sperm motility has also declined: from 79 to 67 percent, although the profile of donors did not change over that period; they are still young, healthy and do not smoke.

According to Haimov-Kokhman, the quality of sperm has declined in most Western countries, but in Israel it has been particularly rapid.

"If we keep going at this rate, a decline of 3 million cubic centimeters of sperm cells per year, we'll reach an average of 20 million in 2030. The World Heath Organization defines this as fertility impairment."

Studies showing a decline in sperm quality began to be published worldwide more than a decade ago, along with research indicating a rise in the rate of defects in the male reproductive system.

In Israel, too, a study was published about a year ago, showing an increase of about 30 percent in defects in the male reproductive system. In addition, in the past decade, the number of cases of testicular cancer has doubled.

A number of chemicals in the ground and in drinking water have been identified as impacting hormone levels and secondary sexual characteristics. These chemicals include plasticizers called phthalates, used in food wrappings, cosmetics and a various insecticides. Studies published in Britain have highlighted a clear connection between continual decline in sperm counts and chemicals in the environment.

"I would suggest that a concentration of estrogen in the water is a cause of change, Haimov-Kokhman says, noting that hormones in the ground come from both human and animal waste that reach the aquifer via sewage. "The ground is full of estrogen that produces estrogen-saturated fruits, vegetables and plants."

A study published in Israel two years ago revealed that the high level of female hormones in a stream near Beit She'an, apparently originating from women swimmers who were taking birth-control pills, caused fish to develop female characteristics. However, the researchers say that the level of hormones in the country's main waterways is negligible, and cannot be the source of impairment of the male reproductive system.

"While it's true that the evidence is only circumstantial, even the connection between smoking and lung cancer took a generation to prove," Haimov-Kokhman notes.